Rpm capability and stroked motors!

We'll start another thread for this discussion.

Originally Posted by 1BADSUPRA
Put any stroker kit you want in the 2jz, and I guarantee you won't even come close to the reciprocating mass that Saad and I run in our Supras, and he consistantly sees over 10krpm! Like I said, there is alot more to it than just "enertial loads". The valvetrain etc.... If your rotating components are designed to handle the rpm for their weight, it's not an issue, geometry however is!...

[QUOTE=pwpanas]Since you posted here instead of PM, I'll do the same: Given your description above, wouldn't you agree that inertial loads in a stroked 2jz-gte at 10K rpm exceed inertial loads in a non-stroked 2jz-gte at 10k rpm? The property of increased inertial loads in a stroker kit is it's primary rpm-limiting factor, and not geometry. I agree that valve float is an issue at higher rpms, but of course that has nothing (directly) to do with a stroker kit..
QUOTE]

No, I wouldn't agree, there are alot of calculations involved, but the short version is, the stroke affects the leverage on the crank, and side loading on the rod. But I definately wouldn't say that just becuase it is stroked it has more enertial load. If you are using titanium or aluminum rods on the stroker, and 850gram steel rods on the 3.0liter....you are going to have more enertial loading on the 3.0. Is this going to limit the rpm? Not necessarily. That is something that is going to be determined by a whole host of other issues that may be necessary to over come.....oiling....bearings....valvtrain...rod bolt strength....I could go on and on... You get the idea. I have personally had 8.4 liter viper motors turning 8400rpm! How much enertial loading do you think that thing had? If you have the right components.....you can get away with alot!

I have more questions than comments, but this is an interesting subject.

Can you tell us if the stroker motor guys are running unusually large bores? I figure max bore size must be limited on the 2JZGTE even with sleeving. But even slightly bigger diameter pistons would add substantial moving mass. Do stroker pistons have different design piston skirts that also add mass?

As for valvetrain, I wonder how beneficial is it to use those other kind of buckets, I think from that other 4cyl Toyota motor, 3SG or somethiing like that, sorry for my lingo deficiency. The numbers I remember reading said they are much lighter and therefore help reduce moving valvetrain mass.

While I'm more attracted to smaller than average turbos on Supras, the large turbos for sure, and even the smaller ones, seem to benefit from higher rpm's on the 2JZGTE. If I could afford it, I'd go stroker right now, but for me that will have to be something for the future.

...No, I wouldn't agree, there are alot of calculations involved, but the short version is, the stroke affects the leverage on the crank, and side loading on the rod. But I definately wouldn't say that just becuase it is stroked it has more enertial load. If you are using titanium or aluminum rods on the stroker, and 850gram steel rods on the 3.0liter....you are going to have more enertial loading on the 3.0. Is this going to limit the rpm? Not necessarily. That is something that is going to be determined by a whole host of other issues that may be necessary to over come.....oiling....bearings....valvtrain...rod bolt strength....I could go on and on... You get the idea. I have personally had 8.4 liter viper motors turning 8400rpm! How much enertial loading do you think that thing had? If you have the right components.....you can get away with alot!
Your initial question (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23) asked "What about stroke decreases revving capability?". Again, the general answer to that question is increased inertial loads. Of course you can lighten the components to reduce inertial loads, but your question did not state nor imply that the stroked engine would be running (for example) titanium rods. You highlighting the fact that one could run lighter components in a stroked engine only serves as further evidence that increased inertial loads actually is the primary factor in decreased rpm capability in a stroked engine. I agree that geometry/leverage and side-loading are factors, but they're by far secondary considerations (as long as we keep this in the context of a 3L 2jz-gte stroked up to about 3.3L).

Your initial question (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23) asked "What about stroke decreases revving capability?". Again, the general answer to that question is increased inertial loads. Of course you can lighten the components to reduce inertial loads, but your question did not state nor imply that the stroked engine would be running (for example) titanium rods. You highlighting the fact that one could run lighter components in a stroked engine only serves as further evidence that increased inertial loads actually is the primary factor in decreased rpm capability in a stroked engine. I agree that geometry/leverage and side-loading are factors, but they're by far secondary considerations (as long as we keep this in the context of a 3L 2jz-gte stroked up to about 3.3L).

No......it isn't. You are assuming the stock components are not strong enough to take the rpm. You can't assume that! My question was a way to make you think about what that is...rather than doing what everyone else does, and just assume that because there is more stroke....surely you can't rev the engine as high. A stock 2jz and a stroker kit for a 2jz have the same rpm capability!

No......it isn't. You are assuming the stock components are not strong enough to take the rpm. You can't assume that! My question was a way to make you think about what that is...rather than doing what everyone else does, and just assume that because there is more stroke....surely you can't rev the engine as high...On the contrary, I never stated nor assumed that there would be an oem component swap (show me a post where I said this). What I've said along is, all other things (i.e. components) being equal, at the same rpm, a stroker will have significantly higher inertial loads, and that's the primary rev-limiting factor. In order to avoid damage due to those higher inertial loads, the rpm limit must be decreased OR components must be swapped.

...A stock 2jz and a stroker kit for a 2jz have the same rpm capability!...Yes, but only because stroker kits typically provide lighter and/or stronger components...lighter components as a proactive measure to minimize the increase to inertial loads, and/or stronger components in order to deal with those increased inertial loads.

On the contrary, I never stated nor assumed that there would be an oem component swap (show me a post where I said this). What I've said along is, all other things (i.e. components) being equal, at the same rpm, a stroker will have significantly higher inertial loads, and that's the primary rev-limiting factor. In order to avoid damage due to those higher inertial loads, the rpm limit must be decreased OR components must be swapped..

What???? I just said you were assuming the STOCK components couldn't handle it....what does swapping anything have to do with that? I would rev a stock 2jz to 8k with cams...no problem. Those same stock type components on a 3.4 stroker, I would have no problem turning the same rpm.

Yes, but only because stroker kits typically provide lighter and/or stronger components...lighter components as a proactive measure to minimize the increase to inertial loads, and/or stronger components in order to deal with those increased inertial loads.

No, I definately would NOT say that is the primary factor. I would say Valvetrain is the PRIMARY concern. Strenth of the the bottom end would be secondary, in nearly every case. Factory components these days are quite good, the valvetrain on the other hand is in most cases sub-par.

What???? I just said you were assuming the STOCK components couldn't handle it....what does swapping anything have to do with that? I would rev a stock 2jz to 8k with cams...no problem. Those same stock type components on a 3.4 stroker, I would have no problem turning the same rpm...Yes, but you're comparing apples to oranges. The 8k rev limit on a "stock 2jz" is due to the valvetrain, but the 8k rev limit on a 3.4 stroker is due to inertial loads on the bottom end. Put an upgraded valvetrain in both, with near-identical bottom end components, and the "stock 2jz" will have lower inertial loads and a higher safe rpm limit.

No, I definately would NOT say that is the primary factor. I would say Valvetrain is the PRIMARY concern. Strenth of the the bottom end would be secondary, in nearly every case. Factory components these days are quite good, the valvetrain on the other hand is in most cases sub-par.
Fwiw, I also agree with you that valvetrain is a primary concern as you raise rpm ... however that has nothing at all to do with whether or not the bottom end is stroked (and therefore not relevant to your initial question (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23)).

I also agree that strength of the bottom end is important...among other things to deal with increased inertial loads of higher rpms, especially if the owner decides to put on a stroker kit.

Yes, but you're comparing apples to oranges. The 8k rev limit on a "stock 2jz" is due to the valvetrain, but the 8k rev limit on a 3.4 stroker is due to inertial loads on the bottom end. Put an upgraded valvetrain in both, with near-identical bottom end components, and the "stock 2jz" will have lower inertial loads and a higher safe rpm limit.


Fwiw, I also agree with you that valvetrain is a primary concern as you raise rpm ... however that has nothing at all to do with whether or not the bottom end is stroked (and therefore not relevant to your initial question (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23)).

I also agree that strength of the bottom end is important...among other things to deal with increased inertial loads of higher rpms, especially if the owner decides to put on a stroker kit.

The point I was trying to make is that just becuase an engine is "stroked" it doesn't mean you lose the engines ability to rev, and the PRIMARY concern (as you put it) isn't the enertail loads, it's geometry (if we are excluding the cylinder head concerns). I would be much more concerned with rod angles, than the mechanical components ability to handle the rpm.

The point I was trying to make is that just becuase an engine is "stroked" it doesn't mean you lose the engines ability to rev, and the PRIMARY concern (as you put it) isn't the enertail loads, it's geometry (if we are excluding the cylinder head concerns). I would be much more concerned with rod angles, than the mechanical components ability to handle the rpm.Why do you feel that rod geometry is more of a concern than inertial loads?

Why do you feel that rod geometry is more of a concern than inertial loads?

Becuase 99.99% of the time, the components involved on the bottom end will handle the extra 'swing', the side loading of the rod may not!

Becuase 99.99% of the time, the components involved on the bottom end will handle the extra 'swing', the side loading of the rod may not!You can't say that as a general statement, without considering the RPM. For example perhaps "the bottom end will handle the extra 'swing'" at 10,500 rpm, but NOT at 11,500 rpm. Just because any given Supra owner might keep his Supra owner below 11K rpm 99.99% of the time on average does NOT somehow automatically translate into side loading being the primary rev limiting factor of stroking an engine.

Let's put it this way: Fwiw, I'm 100% sure that a stroked 2jz-gte with an upgraded valvetrain running 11k rpm for an extended period would fail due to increased inertial loads, and NOT side loading of the rod. How do we go about resolving this one way or another without blowing up a $10K engine and doing another $3K+ of failure analysis work? ...or do we simply agree to disagree?

You can't say that as a general statement, without considering the RPM. For example perhaps "the bottom end will handle the extra 'swing'" at 10,500 rpm, but NOT at 11,500 rpm. Just because any given Supra owner might keep his Supra owner below 11K rpm 99.99% of the time on average does NOT somehow automatically translate into side loading being the primary rev limiting factor of stroking an engine.

Let's put it this way: Fwiw, I'm 100% sure that a stroked 2jz-gte with an upgraded valvetrain running 11k rpm for an extended period would fail due to increased inertial loads, and NOT side loading of the rod. How do we go about resolving this one way or another without blowing up a $10K engine and doing another $3K+ of failure analysis work? ...or do we simply agree to disagree?

I guess I made the assumption that we were talking actual real world scenarios...not some ficticous maybe if when scenarios. In the real world (where we spend most of our days) the engine would have never made it to 11k becuase the valves would have floated and the buckets kicked out...then the pistons sent the valves into the combustion chamber...breaking the valves...pistons...and possibly the wrist pins and or rods! Also in the real world, side loading is an issue long before the 11k rpm. The rod angle is critical at speeds starting at peak torque.

I guess I made the assumption that we were talking actual real world scenarios...not some ficticous maybe if when scenarios. In the real world (where we spend most of our days) the engine would have never made it to 11k becuase the valves would have floated and the buckets kicked out...then the pistons sent the valves into the combustion chamber...breaking the valves...pistons...and possibly the wrist pins and or rods!Of course they would...but again, the limitations of the oem valvetrain has nothing to do with why longer "stroke decreases revving capability (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23)".

...Also in the real world, side loading is an issue long before the 11k rpm. The rod angle is critical at speeds starting at peak torque.I see. So if torque peak occurs at (for example) 6k rpm, then that is the rpm where rod angle and side loading is an issue. Since 6k rpm is and 6k rpm is far below the max rpm of both an oem and a stroked 2jz-gte bottom end, it seems you're saying that rod angle and side loading really doesn't have any impact at all on why longer "stroke decreases revving capability (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23)"...

Of course they would...but again, the limitations of the oem valvetrain has nothing to do with why longer "stroke decreases revving capability (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23)".

I see. So if torque peak occurs at (for example) 6k rpm, then that is the rpm where rod angle and side loading is an issue. Since 6k rpm is and 6k rpm is far below the max rpm of both an oem and a stroked 2jz-gte bottom end, it seems you're saying that rod angle and side loading really doesn't have any impact at all on why longer "stroke decreases revving capability (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23)"...

No...it plays a huge roll. When you load the rod from higher angles, the rod weakens at a very high rate, obviously it can handle the most stress straight up and down, so as you increase rod angle, you decrease it's strength. If you are trying to get that ultimately a shorter stroke will rev higher than a longer one...then yes, it does play a part, but it is not the only consideration. In my experience (real world) a 3.4 stroker is just as capable at running the same reliable rpms that any of the 3.0 engines are. I.E. the stroke is NOT the limiting factor.

Now, can we get on with something more useful...like why in this day and age, does it still take so long for a computer to boot up?:) Or why it seems that my very first computer (a 266mhz) seemed to run just as fast as my 64bit 3.5ghz machine?:):)

This is a great conversations!!!! Guys I appreciate your dialogue, as it's VERY informative.

Jason, my question is, are there mathmatical equations that can help you determine degredation in strength? Given using the same material on the rod, as you increase the stroke i.e. increasing the angle, how quickly, or how much it weakens as the stroke is changed?

Chris

This is a great conversations!!!! Guys I appreciate your dialogue, as it's VERY informative.

Jason, my question is, are there mathmatical equations that can help you determine degredation in strength? Given using the same material on the rod, as you increase the stroke i.e. increasing the angle, how quickly, or how much it weakens as the stroke is changed?

Chris

Absolutely! There are several things to consider, but yeah, you can calculate it out.

Now, can we get on with something more useful...like why in this day and age, does it still take so long for a computer to boot up?:) Or why it seems that my very first computer (a 266mhz) seemed to run just as fast as my 64bit 3.5ghz machine?:):)


I was thinking the same thing....... My computer seemed so fast when it was new.... now it takes forever just to boot. Why do some software progrmas run in the background even if you are not using them? Is there a way to shut these things off?

I was thinking the same thing....... My computer seemed so fast when it was new.... now it takes forever just to boot. Why do some software progrmas run in the background even if you are not using them? Is there a way to shut these things off?


I'm not the one to give others PC advise, but I do work on mine as needed.

You probably have to do several things to cover them all unless you know how to get right at the one you want to stop. Some programs you will likely have to open the program itself and find the options or setup or whatever and see if you can choose the one that won't load it at startup. I do that with every piece of software that ever loads on mine since some are notorious at taking over your PC ...Real software is one of my most hated sources of inappropriate overbearing software but there are lots of others.

If you haven't done it recently, hitting "control,alt,delete" and then looking in task manager will show what is running at any given time.

Also, you can look in the "Startup" folder to see what is in there that might load. Go to Control Panel, Taskbar and Start Menu Properties, Advanced, then look at "Remove" to see what is already there and if you want to take anything out, also look in "Advanced" at the directory tree and then in "Startup" folder to see if something you don't want to start is in there.

As far as technical advancements of PC's, yes they're faster and more powerful but at what compromise? I still have my first PC that I ever bought functioning at home, this was a DOS machine before the first MS Windows even came out. I got it in 1986, it's an NEC with a 10MHz 80286 processor (wow, that was hot in those days! and before the 80386 even came out) with the largest harddrive you could get for it a 40 meg harddrive ...now I have 25 times that much memory!... and the fastest RAM all of 256k! I still run Wordperfect and a few other things on that machine and from the time I hit the power "on" button, it boots up and I can be open in Wordperfect and typing within less than 10 seconds.

My final "non-computer professional" opinion is that Windows absolutely sucks and Microsoft's dinosaur approach to PC software is the root of most of these problems. But until recently, we didn't have much choice. Long live Linux and related operating systems!

...using the same material on the rod, as you increase the stroke i.e. increasing the angle, how quickly, or how much it weakens as the stroke is changed?Chris


Getting more on topic than PC BS...

This may be somewhat obvious but the cross sectional design of the rods, not just the material of the rod, is extremely important in regards to bending stiffness/strength. With the same rod material the cross section shape is very signficant as to strength and stiffness. That's why they have H beam rods and I beam rods and some of those are better than others. The length of the cross section from the centerline of bending is more important than the actual metal area of the rod.

And the longer the beam length of an end supported beam (the rod) the more bending stress from loads not inline with the rod. So when the crank arm is horizontal, does that angle put the rod into max bending? I'm trying to picture that geometry ...is that where the rod is at maximum bending load? or is it somewhere else in the stroke cycle?

Getting more on topic than PC BS...

This may be somewhat obvious but the cross sectional design of the rods, not just the material of the rod, is extremely important in regards to bending stiffness/strength. With the same rod material the cross section shape is very signficant as to strength and stiffness. That's why they have H beam rods and I beam rods and some of those are better than others. The length of the cross section from the centerline of bending is more important than the actual metal area of the rod.

And the longer the beam length of an end supported beam (the rod) the more bending stress from loads not inline with the rod. So when the crank arm is horizontal, does that angle put the rod into max bending? I'm trying to picture that geometry ...is that where the rod is at maximum bending load? or is it somewhere else in the stroke cycle?

I should have stated that I was thinking the rod width was the same on the rod as well as the material used.

I'm very interested in the rpm capabilities of having a stroker 3L. So by moving the pin up higher onto the piston like the hks pistons are, does that theoretically put more stress on the cyl wall? moreover, having a non square ratio with the increased stroke? Help me out, I'm learning here ;)
For that matter, why do the hks stroker pistons come .040over? wouldn't that really hurt block strength? The increase stress on the added angle on a bored cyl wall don't seem like a good combination.

I guess I'd like to know what would be the best case scenario in adding disp. without loosing rpm ability?

Chris

...why do the hks stroker pistons come .040over? wouldn't that really hurt block strength?...Chris


I'll wait to hear about most of these questions from the experts, but I think the 40 over pistons could have been decided on so that the displacement actually goes up a reasonable amount. Even with that, it's only an extra 0.4 liters; without the oversized pistons, maybe it would be such a small incremental increase in displacement that almost no one would go for it.

As far as hurting block strength, to me it seems that the 2JZGTE stroker motors actually in real life service prove that is not a concern since they are putting out way over 1000hp.

I'll wait to hear about most of these questions from the experts, but I think the 40 over pistons could have been decided on so that the displacement actually goes up a reasonable amount. Even with that, it's only an extra 0.4 liters; without the oversized pistons, maybe it would be such a small incremental increase in displacement that almost no one would go for it.

As far as hurting block strength, to me it seems that the 2JZGTE stroker motors actually in real life service prove that is not a concern since they are putting out way over 1000hp.

my understanding is that the diameter of the pistons don't really effect the displacement, but it's the actual crank throw, rod length, and piston compression height, correct? And .4L is a 13% increase in displacement, so it's not all that small.
Does the larger diameter piston allow for more rod travel so it doesn't slap the skirt?

since the weekend is upon us, I'm glad you said "slap the skirt"

Have a nice weekend.

No...it plays a huge roll. When you load the rod from higher angles, the rod weakens at a very high rate, obviously it can handle the most stress straight up and down, so as you increase rod angle, you decrease it's strength...Ok, but there seems to be no tie to higher rpms in this line of thought. Again, how do we go about resolving this one way or another without blowing up a $10K engine and doing another $3K+ of failure analysis work? ...or do we simply agree to disagree?

...If you are trying to get that ultimately a shorter stroke will rev higher than a longer one...then yes, it does play a part, but it is not the only consideration...No what we've been discussing is WHY the shorter stroke will rev higher. What I'm trying to get to is a point where it's plain that the shorter stroke revs higher primarily due to lower intertial loads...in order to establish the correct answer to your initial question (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23).

...In my experience (real world) a 3.4 stroker is just as capable at running the same reliable rpms that any of the 3.0 engines are. I.E. the stroke is NOT the limiting factor...Fully built 3.0 vs. built&stroked 3.4, the 3.0 will reliably out-rev the 3.4. If you're comparing a stock (i.e. non-built) 3.0 to a fully 'built' 3.4, then of course the 3.4 can match the max reliable rpm.

...Now, can we get on with something more useful...Hmmmm, fwiw I wouldn't generally recommend suggest starting threads on topics you don't consider useful. ;)

I don't think any of you guys knows what the hell you are talking about!!

C'Mon guys. It's so simple maybe you need a refresher course. It's all ball bearings nowadays. - Fletch

Ok, but there seems to be no tie to higher rpms in this line of thought. Again, how do we go about resolving this one way or another without blowing up a $10K engine and doing another $3K+ of failure analysis work? ...or do we simply agree to disagree?

No what we've been discussing is WHY the shorter stroke will rev higher. What I'm trying to get to is a point where it's plain that the shorter stroke revs higher primarily due to lower intertial loads...in order to establish the correct answer to your initial question (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23).

Fully built 3.0 vs. built&stroked 3.4, the 3.0 will reliably out-rev the 3.4. If you're comparing a stock (i.e. non-built) 3.0 to a fully 'built' 3.4, then of course the 3.4 can match the max reliable rpm.

Hmmmm, fwiw I wouldn't generally recommend suggest starting threads on topics you don't consider useful. ;)

Your lost.... Your initial statement was that inertial weight was the PRIMARY concern when revving a stroker motor.....it isn't.....period. This isn't a matter of opinion, one has to look at all the facts, and decide from there what the Primary concern is for the given setup. On one engine it may very well be inertial loads, on the 2J...this is NOT the case. You can't make a blanket statement like that....it just doesn't hold true. Just out of curiosity, how many engines have you built? How many have you race, and or blown up learning? There are alot of things that look great in theory or on paper, that just don't quite work out in the real world.

Your lost.... Your initial statement was that inertial weight was the PRIMARY concern when revving a stroker motor.....it isn't.....period. This isn't a matter of opinion, one has to look at all the facts, and decide from there what the Primary concern is for the given setup. On one engine it may very well be inertial loads, on the 2J...this is NOT the case. You can't make a blanket statement like that....it just doesn't hold true. Just out of curiosity, how many engines have you built? How many have you race, and or blown up learning? There are alot of things that look great in theory or on paper, that just don't quite work out in the real world.Saying that someone else is lost, or that inertial loading is not the primary concern, is easy ... but proving your case is another matter.

You say we should look at the facts, but so far you haven't presented any facts that directly show why rod angles are more of a factor at max rpm than inertial loading, when considering rev limit in a built&stroked a 2jz (versus a built non-stroked 2jz). I agree that neither of us should make blanket statements, so let's either agree to disagree (which is totally fine with me) ... or perhaps you can share some cold, hard relevant facts that you've learned from all the engines you've blown up?

Saying that someone else is lost, or that inertial loading is not the primary concern, is easy ... but proving your case is another matter.

You say we should look at the facts, but so far you haven't presented any facts that directly show why rod angles are more of a factor at max rpm than inertial loading, when considering rev limit in a built&stroked a 2jz (versus a built non-stroked 2jz). I agree that neither of us should make blanket statements, so let's either agree to disagree (which is totally fine with me) ... or perhaps you can share some cold, hard relevant facts that you've learned from all the engines you've blown up?

Primary concern would be the first thing that becomes a problem....correct???
I am going to assume that since your an engineer...your intelligent, and your answer is yes.

So...since the first thing that becomes a problem is rod angle, which starts to be a problem as soon as cylinder pressure starts increasing, and just gets worse as rpm goes up. This would be your primary concern, becuase it becomes an issue much sooner than any rotating mass does. THink of it this way, the greater the rod angle, the more the crank is trying to push the rod and piston through the side of the cylinder wall...rather than up! Inertial loads may or may not be a problem....ever, depending upon the components used. Rod angle is ALWAYS a consideration, and I would always consider that 2nd right after the cylinder head componets (which as you pointed out is not affected by a change in stroke. So it's like this

1) Valve train design and capabilities
2) The flow capabilities of the cylinder head and all related components (Cam, Intake, turbo (if applicable), exhuast...doesn't do you much good to rev an engine that quit making power 1000rpm's ago.
3) Lower end geometry (I.E. rod angle, piston speed, rod journal split, bearing speeds...etc..)
4) Rotating mass assembly ( piston weight, rod weight, crank weight, clutch or flywheel assembly weight).

Actually, when you break it down, I would consider the inertial weight last. Now ofcourse every setup is going to have it's order of priority, but you still would go through it in that order. For example...take an NSX engine. The cylinder heads and valve train...near perfect, Intake manifold....junk above 8k, so there is your "Primary concern".

Primary concern would be the first thing that becomes a problem....correct???...Only as the concern directly relates to the topic as stated, which is "What about stroke decreases revving capability? (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23)".
...a problem is rod angle, which starts to be a problem as soon as cylinder pressure starts increasing...Ok, but...

...and just gets worse as rpm goes up...Are you saying that the rod angle problem gets worse as rpm goes up to the point of torque peak, or do you say that it continues to get worse and more worse all the way to max rpm?

...This would be your primary concern, becuase it becomes an issue much sooner than any rotating mass does...It depends. We're not ordering this list by rpm point, nor should it be prioritized according to overall power production considerations. We are specifically talking about first in a prioritized list of possible concerns as they directly relate to why increased "stroke decreases revving capability (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23)".

...THink of it this way, the greater the rod angle, the more the crank is trying to push the rod and piston through the side of the cylinder wall...rather than up!...Of course...but why is that an increasing problem past torque peak?

...Inertial loads may or may not be a problem....ever, depending upon the components used...There's an rpm point where any set of components will fail, so considering inertial loads at max rpm is ALWAYS a problem.

...every setup is going to have it's order of priority, but you still would go through it in that order. For example...take an NSX engine. The cylinder heads and valve train...near perfect, Intake manifold....junk above 8k, so there is your "Primary concern".In this example, the intake manifold does not limit rpm above 8k. It may limit the ability to efficiently produce power above 8k, but if you wound that engine to 15k in a lower gear, the NSX engine would fail due to increased inertial loads and not due to a restrictive intake manifold.

Only as the concern directly relates to the topic as stated, which is "What about stroke decreases revving capability? (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23)".
Ok, but...

Are you saying that the rod angle problem gets worse as rpm goes up to the point of torque peak, or do you say that it continues to get worse and more worse all the way to max rpm?

It depends. We're not ordering this list by rpm point, nor should it be prioritized according to overall power production considerations. We are specifically talking about first in a prioritized list of possible concerns as they directly relate to why increased "stroke decreases revving capability (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23)".

Of course...but why is that an increasing problem past torque peak?

There's an rpm point where any set of components will fail, so considering inertial loads at max rpm is ALWAYS a problem.

In this example, the intake manifold does not limit rpm above 8k. It may limit the ability to efficiently produce power above 8k, but if you wound that engine to 15k in a lower gear, the NSX engine would fail due to increased inertial loads and not due to a restrictive intake manifold.

1) yes...absolutely the rod angle becomes more and more of a concern as rpm increases. More frequency = more stress...rpm is essentially frequency.

2) the intake manifold in the NSX example ablsolutely limits rpm, when the engine can't pull air in, it quits revving.

3) Your making blanket statements again. Components inertial loads are not a consideration all the time. If you are building and engine that you want a usable power band from say 4krpm to 8krpm...regardless of stroke... inertial weights isn't automatically a concern. Yes if you tried to rev said engine to 14k...then maybe, but NO ONE does that... You build an engine to operate in a given rpm range, and 99 times out of 100 the weight of those components is not a concern within that rpm range. So it is NOT A PRIMARY concern by any means

the list stands!

1) yes...absolutely the rod angle becomes more and more of a concern as rpm increases. More frequency = more stress...rpm is essentially frequency...I'm glad you agree...since the primary reason that more frequency = more stress is because if increased inertial loads.

2) the intake manifold in the NSX example ablsolutely limits rpm, when the engine can't pull air in, it quits revving...Come on...you don't expect us to believe that an NSX with the rev limit disabled, running downhill, with the wind in 1st gear with the gas pedal jammed to the floor won't hit at least 10K rpm? ...or in neutral?

3) Your making blanket statements again. Components inertial loads are not a consideration all the time. If you are building and engine that you want a usable power band from say 4krpm to 8krpm...regardless of stroke... inertial weights isn't automatically a concern. Yes if you tried to rev said engine to 14k...then maybe, but NO ONE does that... You build an engine to operate in a given rpm range, and 99 times out of 100 the weight of those components is not a concern within that rpm range. So it is NOT A PRIMARY concern by any means...Rpm limits aren't there to keep you in the "useable power band". They exist to prevent the engine from blowing up (because of increased inertial loads). So if we're talking about rpm limits, inertial loads are most definitely A PRIMARY concern.

the list stands!Fwiw, your "list" appears to be (imho) items that might help to widen the power band in a stroked engine, which is a list very much unrelated to the topic of this thread (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23). If you'd like for your list to stand, you're the only one in this discussion that does. Imo, you certainly haven't proven that the items on it are more critical than increased inertial loads, as they directly relate to why increased "stroke decreases revving capability (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23)".

I'm glad you agree...since the primary reason that more frequency = more stress is because if increased inertial loads.

Come on...you don't expect us to believe that an NSX with the rev limit disabled, running downhill, with the wind in 1st gear with the gas pedal jammed to the floor won't hit at least 10K rpm? ...or in neutral?

Rpm limits aren't there to keep you in the "useable power band". They exist to prevent the engine from blowing up (because of increased inertial loads). So if we're talking about rpm limits, inertial loads are most definitely A PRIMARY concern.

Fwiw, your "list" appears to be (imho) items that might help to widen the power band in a stroked engine, which is a list very much unrelated to the topic of this thread (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23). If you'd like for your list to stand, you're the only one in this discussion that does. Imo, you certainly haven't proven that the items on it are more critical than increased inertial loads, as they directly relate to why increased "stroke decreases revving capability (http://www.thesupraforums.com/showpost.php?p=9985&postcount=23)".

1)Inertial loads have nothing to do with the side loading stress on the rod as rpm increases.....stick to fixing why my computer take so long to boot up!

2) Operating out of the design of the engine, has nothing to do with this discussion....your statement on running the nsx engine to 11k just proves your ignorance. The factory bottom end would survive this scenario.....the valvetrain wouldn't. Talk to anyone who has accidentally hit 2nd instead of 4th on a down shift and overrevved their engine.....the valve train fails first. I have NEVER heard of anyone tossing a rod due to this scenario

So once again it is NOT a primary concern..it may be a primary concern for you, as you clearly have no engine building experience, or engine failure experience. The rest of us here don't live in hypothetical situations, we live in the real world. Maybe that's where your having a hard time seperating the software world with the real life world.

1)Inertial loads have nothing to do with the side loading stress on the rod as rpm increases...Sure they do, although the rpm point where these two tie together is likely rather high (so high in fact that inertial loads would cause other types of failures long beforehand). On the other hand, you still haven't shown why side loading stress on the rod goes up when torque goes down as the rpm limit is approached...

...stick to fixing why my computer take so long to boot up!You're the expert at coverups and marketing 'spin' on bugs in software releases. Hello pot, this is kettle...

...2) Operating out of the design of the engine, has nothing to do with this discussion....your statement on running the nsx engine to 11k just proves your ignorance. The factory bottom end would survive this scenario.....the valvetrain wouldn't. Talk to anyone who has accidentally hit 2nd instead of 4th on a down shift and overrevved their engine.....the valve train fails first. I have NEVER heard of anyone tossing a rod due to this scenarioSure rpm limits exist to protect against several kinds of damage...but since you're so passionately touting "real world" applications, who builds a stroked engine with an oem valvetrain? Of course, no one does, so your repeated references to valvetrain failure should be kept out of this discussion.

...So once again it is NOT a primary concern..it may be a primary concern for you, as you clearly have no engine building experience, or engine failure experience. The rest of us here don't live in hypothetical situations, we live in the real world. Maybe that's where your having a hard time seperating the software world with the real life world.Once again, you've failed to prove your point. In addition, your regressions into personal attacks lead me to believe you don't have the data to back up your assertions on this topic.

Sure they do, although the rpm point where these two tie together is likely rather high (so high in fact that inertial loads would cause other types of failures long beforehand). On the other hand, you still haven't shown why side loading stress on the rod goes up when torque goes down as the rpm limit is approached...

You're the expert at coverups and marketing 'spin' on bugs in software releases. Hello pot, this is kettle...

Sure rpm limits exist to protect against several kinds of damage...but since you're so passionately tout "real world" applications, who builds a stroked engine with an oem valvetrain? Of course, no one does, so your repeated references to valvetrain failure should be kept out of this discussion.

Once again, you've failed to prove your point. In addition, your regressions into personal attacks lead me to believe you don't have the data to back up your assertions on this topic.

I'll tell you what....when you come up with the data...I'll provide data. For now, I'll rely on my experience you rely on yours....building PC's! As far as "coverups, and Marketing spins on software bugs". I'll mark this one again as your complete and utter ignorance with your lack of competance, or understanding with engines and cars.

Sure rpm limits exist to protect against several kinds of damage...but since you're so passionately tout "real world" applications, who builds a stroked engine with an oem valvetrain? Of course, no one does, so your repeated references to valvetrain failure should be kept out of this discussion.


I hope you are referring to 2JZ engines here.

Valve trains do matter in this discussion, just because the question was what about stroke limits rpm, doesn't mean you ignore the capabilities of the valvetrain, then come up with some hypothetical situation to try and prove a case you yourself don't understand.

so in my .02 overbored 7m-gte how much extra displacement could i look at gettin?????

...I'll tell you what....when you come up with the data...I'll provide data...Ok, here you go:
http://www.eng-tips.com/viewthread.cfm?qid=85349
http://e30m3performance.com/tech_articles/engine-tech/rod-ratio/index.htm
http://e30m3performance.com/tech_articles/engine-tech/rod-ratio/kin2.htm
If side loading the huge, pervasive, primary rpm-limiting factor that you say it is ... something that must keep all engine builders tossing in turning during their sleep every night ... then explain why neither of these discussions on rpm and rod:stroke ratio even mentions it.
...For now, I'll rely on my experience you rely on yours....building PC's!WTF are you talking about? Again, your poor attempts to distract the readers of this tread with off-base personal attacks leads me to believe you don't have the data to back up your assertions on this topic.
...As far as "coverups, and Marketing spins on software bugs". I'll mark this one again as your complete and utter ignorance with your lack of competance, or understanding with engines and cars.I'm sure it's either that, or blind arrogance (http://www.supraforums.com/forum/showpost.php?p=2393289&postcount=148) on your part (http://www.supraforums.com/forum/showthread.php?t=230779&page=5&pp=30)...
Valve trains do matter in this discussion, just because the question was what about stroke limits rpm, doesn't mean you ignore the capabilities of the valvetrain, then come up with some hypothetical situation to try and prove a case you yourself don't understand.So I guess this means you regularly build stroked 2jz-gte's with a bone-stock valvetrain?

I hope you are referring to 2JZ engines here.Yes, of course. Have you ever heard of someone spending $5K+ on parts to stroke the 2jz-gte bottom end, and then only run a bone-stock valvetrain in the 2jz-gte head that's bolted onto the stroked bottom end?

Ok, here you go:
http://www.eng-tips.com/viewthread.cfm?qid=85349
http://e30m3performance.com/tech_articles/engine-tech/rod-ratio/index.htm
http://e30m3performance.com/tech_articles/engine-tech/rod-ratio/kin2.htm
If side loading the huge, pervasive, primary rpm-limiting factor that you say it is ... something that must keep all engine builders tossing in turning during their sleep every night ... then explain why neither of these discussions on rpm and rod:stroke ratio even mentions it.
WTF are you talking about? Again, your poor attempts to distract the readers of this tread with off-base personal attacks lead me to believe you don't have the data to back up your assertions on this topic.
I'm sure it's either that, or blind arrogance (http://www.supraforums.com/forum/showpost.php?p=2393289&postcount=148) on your part (http://www.supraforums.com/forum/showthread.php?t=230779&page=5&pp=30)...
So I guess this means you regularly build stroked 2jz-gte's with a bone-stock valvetrain?

Just so I have this straight, no one builds a stroker motor with a stock valvetrain, but EVERYONE builds a stroker motor with sub par components that limit their rpm capability? You should find a different engine builder.

Just so I have this straight, no one builds a stroker motor with a stock valvetrain, but EVERYONE builds a stroker motor with sub par components that limit their rpm capability? You should find a different engine builder.No you don't have this straight. Even a shortblock with the best of the best bottom-end internal components will fail at a high enough rpm, due to increased inertial loads. That rpm failure point is lower for a stroked engine, because the piston travels further during each revolution. For a given rpm value, the inertial loads in a stroker are higher than the equivalent non-stroked engine.

No you don't have this straight. Even a shortblock with the best of the best bottom-end internal components will fail at a high enough rpm, due to increased inertial loads. That rpm failure point is lower for a stroked engine, because the piston travels further during each revolution. For a given rpm value, the inertial loads in a stroker are higher than the equivalent non-stroked engine.


So....since this "RPM" is well beyond the mechanicl limits of the rest of the engines capable performance limits...you consider this a primary concern.


Got it!

So....since this "RPM" is well beyond the mechanicl limits of the rest of the engines capable performance limits...you consider this a primary concern...Failure due to exessive inertial load will occur long before (for example) failure of a decent double-spring valvetrain...especially with a stroker. When a rev limit is set to for example 10K, it's to prevent failure due to excessive inertial loads immediately beyond that point. We're not talking about (for example) a failure that might only occur at 25K rpm.
...so yes, when setting the rev limit, with either a stroked or non-stroked bottom end, inertial loads is not only a primary concern, it is the primary concern.

I always wonder why nobody uses lightweight rotating assembly(titanium rods,lightweight crank) for high rpm?Also no lightweight strokers?

I always wonder why nobody uses lightweight rotating assembly(titanium rods,lightweight crank) for high rpm?Also no lightweight strokers?One reason I'm aware of is that titanium rods generally aren't as durable (from a longevity/service life/mileage perspective) as rods made of forged steel (chromium/nickel/vanadium/molybdenum) alloy... In a trailered, dragstrip-only engine they would (as you suggest) allow for a higher rpm capability, due to reduced inertial loads. Fwiw, I wouldn't recommend them for a street-driven Supra that you'd expect to get tens (or hundreds) of thousands of miles out of.

Is that really still true about titanium if the correct alloy and fab process is used for the part? I think Ti does have substantially lower fatigue limits, but I thought that the correctly processed alloy would make it a moot point in real life, and not just for a dedicated race car.

Examples I'm thinking of are the titanium rods used in Porsches for many years, and I think even the LS7 uses titanium rods. I don't think those are considered relatively short life replacement items.

Failure due to exessive inertial load will occur long before (for example) failure of a decent double-spring valvetrain...especially with a stroker. When a rev limit is set to for example 10K, it's to prevent failure due to excessive inertial loads immediately beyond that point. We're not talking about (for example) a failure that might only occur at 25K rpm.
...so yes, when setting the rev limit, with either a stroked or non-stroked bottom end, inertial loads is not only a primary concern, it is the primary concern.


Says who? The engine in my car has waaayyy more "Inertial loads" than a 3.4 stroker, the rods I use weigh 850grams, a typical 3.4 stroker rod weighs around 450...nearly half that! The pistons aren't the heavy part, the rod is, and the majority of the rod weight is around the crank, not the piston, and my valve train is good to well beyond 10k. However, the turbo charger and head flow quit well before that point. I could easily rev the engine to 11k, and accidentally have on a vew occasions...but with any brain cells at all in my head...why would I....the engine doesn't make power there. So it ISN'T a primary concern at all, as the engines flow capabilities are exceeded long before any of the mechanical limits are reached. That is why geometry is much more critical, anyone building a stroker motor is surely going to use good components, capable of running well beyond the flow limits of the engine. So if you want to consider something that will never reasonably be obtained a primary concern...go right ahead. It's a good thing you aren't an engine builder.

Is that really still true about titanium if the correct alloy and fab process is used for the part? I think Ti does have substantially lower fatigue limits, but I thought that the correctly processed alloy would make it a moot point in real life, and not just for a dedicated race car.

Examples I'm thinking of are the titanium rods used in Porsches for many years, and I think even the LS7 uses titanium rods. I don't think those are considered relatively short life replacement items.Good point...although fwiw/imho I'd still have to give the edge (as far as longevity) to a forged steel rod in a 1000rwhp+ 2jz-gte spun up to 10k rpms.

One reason I'm aware of is that titanium rods generally aren't as durable (from a longevity/service life/mileage perspective) as rods made of forged steel (chromium/nickel/vanadium/molybdenum) alloy... In a trailered, dragstrip-only engine they would (as you suggest) allow for a higher rpm capability, due to reduced inertial loads. Fwiw, I wouldn't recommend them for a street-driven Supra that you'd expect to get tens (or hundreds) of thousands of miles out of.

This is a perfect example of your lack of understanding of engines. Do you think that Honda, and GM would build factory engines with Titanium rods if that were the case? Do us all a favor.....don't recomend anything to anyone on this board! Nick 95 sp is right!

Says who? The engine in my car has waaayyy more "Inertial loads" than a 3.4 stroker, the rods I use weigh 850grams, a typical 3.4 stroker rod weighs around 450...nearly half that! The pistons aren't the heavy part, the rod is, and the majority of the rod weight is around the crank, not the piston...I agree that the shorter (and therefore lighter) rods can help to compensate for the increased mean piston speed in a stroker. HOWEVER, I would not agree that your inertial loads are "waaayyy" higher, because you haven't taken into account that your pistons are travelling slower at a given rpm. Also note that this discussion isn't about how heavy the rods are that YOU chose to use in YOUR engine. It's about comparing stroked to non-stroked with all other things being as equal as possible. With your relatively heavy rods, it may very well be that your engine's inertial loads would require setting the rpm limit at a similar point to a stroker...
...my valve train is good to well beyond 10k. However, the turbo charger and head flow quit well before that point. I could easily rev the engine to 11k, and accidentally have on a vew occasions...but with any brain cells at all in my head...why would I....the engine doesn't make power there...Regardless of where you choose to set your rev limit, that rev limit exists to prevent engine damage and NOT to keep you in your optimal power band.
...So it ISN'T a primary concern at all, as the engines flow capabilities are exceeded long before any of the mechanical limits are reached. That is why geometry is much more critical, anyone building a stroker motor is surely going to use good components, capable of running well beyond the flow limits of the engine...Even during an accidental over-rev during a 1st gear burnout? Get this straight - rev limits exist to prevent engine damage, NOT to help the driver stay in his preferred power band.
...So if you want to consider something that will never reasonably be obtained a primary concern...go right ahead...You still haven't proven this. Where is your data?
...It's a good thing you aren't an engine builder.Be honest - neither are you. When was the last time you personally cut valve seats in a 2jz-gte head with a Serdi machine, for example? If you want to keep hitting the personal attacks angle, I'm more than game. However I'd suggest it'd be more productive to leave them out of this converstation.

This is a perfect example of your lack of understanding of engines. Do you think that Honda, and GM would build factory engines with Titanium rods if that were the case? Do us all a favor.....don't recomend anything to anyone on this board! Nick 95 sp is right!Will you pay to replace every APU Supra owner's titanium rods on this board when they fail at 50,000 miles? Again, the longevity of this alloy has NOT been proven in a 1000rwhp+ 2jz-gte spun to 10k+rpm, and the >>>potenital<<< longevity issues with titanium IS valuable information for members of this forum, regardless of your narrow viewpoint.

Will you pay to replace every APU Supra owner's titanium rods on this board when they fail at 50,000 miles? Again, the longevity of this alloy has NOT been proven in a 1000rwhp+ 2jz-gte spun to 10k+rpm, and the >>>potenital<<< longevity issues with titanium IS valuable information for members of this forum, regardless of your narrow viewpoint.

With every statement you look more and more ignorant. If you have titanium rods made for your application, they will be just as durable as a steel rod, just ALOT more expensive. Apparently the living space with in the 2jz block is different than that of the rest of the blocks of this world. So since no one has used them in a 2jz...they aren't "Proven"......give me a break!

I love that you preach inertial loads....then discourage someone from addressing this less than secondary issue........poetic!

With every statement you look more and more ignorant...Seems weak attempts at personal attacks is your forte. Perhaps you should switch to it as a career, since your perspective on rpm limits is so inaccurate...
...If you have titanium rods made for your application, they will be just as durable as a steel rod, just ALOT more expensive. Apparently the living space with in the 2jz block is different than that of the rest of the blocks of this world. So since no one has used them in a 2jz...they aren't "Proven"......give me a break!...Again, where is your data? If you can't see that producing 1500+rwhp at 10K rpm from a 3L engine that is also regularly street-driven makes the 2jz-gte a rather unique application, then your viewpoint is even more twisted than I suspected.
...I love that you preach inertial loads....then discourage someone from addressing this less than secondary issue........poetic!There are various ways to address ANY problem, and the use of titanium isn't the only way to address increased inertial loads. No one is discouraging anyone from addressing this problem. On the other hand, it's more than clear that your ignorance on this overall topic has forced you into trying to find some inconsistency in my assertions. Good luck.

I agree that the shorter (and therefore lighter) rods can help to compensate for the increased mean piston speed in a stroker. .

Wow....and now your talking about rod angle......and you don't even know it.


HOWEVER, I would not agree that your inertial loads are "waaayyy" higher, because you haven't taken into account that your pistons are travelling slower at a given rpm.

Well, why don't you go and run the number for the stroke to speed difference, and weight difference on the rod, and tell me what you come up with.....


Also note that this discussion isn't about how heavy the rods are that YOU chose to use in YOUR engine. It's about comparing stroked to non-stroked with all other things being as equal as possible..

No...the question was directed to why stroke limits the rpm....the point of the question is that IT DOESN'T always....more like very rarely, and definately isn't a "Primary" concern.


With your relatively heavy rods, it may very well be that your engine's inertial loads would require setting the rpm limit at a similar point to a stroker...
Regardless of where you choose to set your rev limit, that rev limit exists to prevent engine damage and NOT to keep you in your optimal power band..

Totally wrong..... you haven't a clue. Who says I use a rev limiter?


Even during an accidental over-rev during a 1st gear burnout? Get this straight - rev limits exist to prevent engine damage, NOT to help the driver stay in his preferred power band.
You still haven't proven this. Where is your data?.

What exactly does the rev limiter have to do with the capability of the rods and pistons, don't change the subject...rev limiters have nothing to dowith this discussion. On a 2j you risk tossing the shims and destroying the valvetrain before the bottom end is an issue....even with a stroker!


Be honest - neither are you. When was the last time you personally cut valve seats in a 2jz-gte head with a Serdi machine, for example?

actually....agout 3 weeks ago...why?


If you want to keep hitting the personal attacks angle, I'm more than game. However I'd suggest it'd be more productive to leave them out of this converstation.

Seems weak attempts at personal attacks is your forte. Perhaps you should switch to it as a career, since your perspective on rpm limits is so inaccurate...
Again, where is your data? If you can't see that producing 1500+rwhp at 10K rpm from a 3L engine that is also regularly street-driven makes the 2jz-gte a rather unique application, then your viewpoint is even more twisted than I suspected..

So you now think that Titanium rods can't be made to accomadate this?

There are various ways to address ANY problem, and the use of titanium isn't the only way to address increased inertial loads. No one is discouraging anyone from addressing this problem. On the other hand, it's more than clear that your ignorance on this overall topic has forced you into trying to find some inconsistency in my assertions. Good luck.

O.k.....name one! You going to find another way to make a STEEL rod lighter with the same power capability? What's next....perpetual motion?

Wow....and now your talking about rod angle......and you don't even know it...The rods are shorter, and the angles are different I agree. However, you STILL haven't shown how that is tied to the rev limit.
...Well, why don't you go and run the number for the stroke to speed difference, and weight difference on the rod, and tell me what you come up with...It's your turn to come up with the data. I haven't seen any yet from you.
...No...the question was directed to why stroke limits the rpm....the point of the question is that IT DOESN'T always....more like very rarely, and definately isn't a "Primary" concern...If that's your opinion, then so be it. However, you've not provided even a shred of evidence yet to support that perspective.
...Totally wrong..... you haven't a clue. Who says I use a rev limiter?...Now that's a responsible recommendation to the members of this forum. :rolleyes:
...What exactly does the rev limiter have to do with the capability of the rods and pistons, don't change the subject...rev limiters have nothing to dowith this discussion. On a 2j you risk tossing the shims and destroying the valvetrain before the bottom end is an issue....even with a stroker!...OMG! The title of this thread is "Rpm capability and stroked motors"...and now you're saying that rev limiters have nothing to do with the discussion? Give me a break... :thumbdown
...actually....agout 3 weeks ago...why?Riiiight. I'll believe it when I see the video. No machine shop owner in their right mind would let an standalone ecu salesman/tuner touch a Serdi machine.

So you now think that Titanium rods can't be made to accomadate this?Can't is a rather strong word. Otoh, what's currently available off-the-shelf for a reasonable $ amount IS relevant to the members of this forum.
O.k.....name one! You going to find another way to make a STEEL rod lighter with the same power capability? What's next....perpetual motion?I never said steel was lighter (find the post if you can). As far as proven solutions for the 2jz-gte, a forged steel alloy rod will be more durable. This means that (due to inertial loads) the rpm limit will need to be set lower than if titanium rods were used. Until off-the-shelf titanium rods have proven themselves, forged steel alloy rods should be the choice for any street-driven Supra owner with a fixed budget to 'build' their engine (which is MOST members of this forum). Unfortunately, not everyone lives in a world of sponsored unlimited budgets...

Can't is a rather strong word. Otoh, what's currently available off-the-shelf for a reasonable $ amount IS relevant to the members of this forum.
No one said steel was lighter (find the post if you can). As far as proven solutions, the forged steel alloy will be more durable. Until off-the-shelf titanium rods have proven themselves, forged steel alloy rods should be the choice for anyone with a fixed budget to modify their engine (which is MOST members of this forum). Unfortunately, not everyone lives in a world of sponsored unlimited budgets...

Again....showing the ignorance...
1) I didn't always work at AEM...and I do use the machines...and I regularly video such a trivial event.... :rolleyes:
2) So now if it has to be made and put in stock to be durable....not just made to order.. There isn't a single off the shelf part in my engine. Custom rods aren't any more expensive than off the shelf rods....just more down time. Show me where nick 95 said cost was a factor?
3) you said there were other solutions to essentially lighten the rotating assembly.....NAME one!

Seriously....stick to making my pc slower!

Again....showing the ignorance...
1) I didn't always work at AEM...and I do use the machines...and I regularly video such a trivial event...Still waiting for the vid, or the contact info for the irresponsible machine shop owner that supposedly let you use his Serdi machine.

...There isn't a single off the shelf part in my engine...Not even the PCV hoses that go between the valve covers? Or the splash tray in the oil pan? Or the cam seals? Give me a break.
Fwiw, I suspect that your piston rings and bearings are off-the-shelf too...

...2) So now if it has to be made and put in stock to be durable....not just made to order... Custom rods aren't any more expensive than off the shelf rods....just more down time. Show me where nick 95 said cost was a factor?...Show me where he said you should assume he could tolerate an unproven solution. Sure there's more downtime for ordering custom parts...but what about the downtime when a set of rods designed for a few 1/4 mile passes that fails at 20K miles, for an APU Supra owner that was expecting them to last at least 100K?
...3) you said there were other solutions to essentially lighten the rotating assembly.....NAME one!Actually what I said is there are other solutions to reduce inertial loads. One option is to lower the rpm limit. Happy?
...Seriously....stick to making my pc slower!Your slow PC is your own issue. You need to remove your skull from your posterior and present some data to support your assertions about rod angles.

Still waiting for the vid, or the contact info for the irresponsible machine shop owner that let you use his Serdi machine.
Show me where he said you should assume he could tolerate an unproven solution. Sure there's more downtime for ordering custom parts...but what about the downtime when a set of rods designed for a few 1/4 mile passes that fails at 20K miles, for an APU Supra owner that was expecting them to last at least 100K?
Actually what I said is there are other solutions to reduce inertial loads. One option is to lower the rpm limit. Happy?
Your slow PC is your own issue. You need to remove your skull from your posterior and present some data to support your assertions about rod angles.

1) your the only one saying they are unproven...and your wrong
2) Lowering the rev limit isn't a solution....if the engine wants to breath to 10k your job as an engine builder is to LET IT! It's only a solution to someone who has no idea on how to build an engine. I suppose when you blow a head gasket, your solution is to not boost the engine!

I have data to support what I am saying....right now...next to me... I'll post mine as soon as you post yours. Which.....you won't because when you do finally repair that pc your working on, and do the research you will find you truly have absolutely no idea what you are talking about.

1) your the only one saying they are unproven...and your wrong...Hokeydokeysmokey... Name ONE 1000rwhp+ 2jz-gte-equipped Mkiv Supra Turbo that has run titanium rods for over 50,000 miles.
...2) Lowering the rev limit isn't a solution....if the engine wants to breath to 10k your job as an engine builder is to LET IT! It's only a solution to someone who has no idea on how to build an engine. I suppose when you blow a head gasket, your solution is to not boost the engine!...You asked me to "name one (http://www.thesupraforums.com/showpost.php?p=10410&postcount=55)" alternative solution to lowering inertial loads, which I successfully did. Now you're trying to further digress by picking holes in it? Again, stick to your futile attempts at showing why you feel rod angles is more of an issue than inertial loads at the rev limit.
I have data to support what I am saying....right now...next to me... I'll post mine as soon as you post yours. Which.....you won't because when you do finally repair that pc your working on, and do the research you will find you truly have absolutely no idea what you are talking about.I've already presented my data (http://www.thesupraforums.com/showpost.php?p=10351&postcount=38). It appears all you're capable of doing is keyboard-warrior-style off-base personal attacks. Now it's your turn to present some relevant data or stfu.

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Honestly this whole discussion has regressed to pointless bantering. I've already suggested that we agree to disagree (http://www.thesupraforums.com/showpost.php?p=10070&postcount=11) on this topic. It appears we've both shared our perspectives on this topic, so why drag this on any further?

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Hokeydokeysmokey... Name ONE 1000rwhp+ 2jz-gte-equipped Mkiv Supra Turbo that has run titanium rods for over 50,000 miles.
You asked me to "name one (http://www.thesupraforums.com/showpost.php?p=10410&postcount=55)" alternative solution to lowering inertial loads, which I successfully did. Now you're trying to further divert the discussion by picking holes in it? Again, stick to your futile attempts at showing why you feel rod angles is more of an issue than inertial loads at the rev limit.
I've already presented my data (http://www.thesupraforums.com/showpost.php?p=10351&postcount=38). It appears all you're capable of doing is keyboard-warrior-style off-base personal attacks. Now it's your turn to present some data or stfu.


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Honestly this whole discussion has regressed to pointless bantering. I've already suggested that we agree to disagree (http://www.thesupraforums.com/showpost.php?p=10070&postcount=11) on this topic. We've both presented our case, so why drag this on any further?

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Find me anyone making 1000+ horsepower for 50k....period. It can be done with the proper Ti rods, as could with steel rods.

No you didn't "successfully" come up with an alternative and you can't!

You haven't shown any data....whatsoever. You crack me up with this stuff...your can't even get your own story straight!

Find me anyone making 1000+ horsepower for 50k....period. It can be done with the proper Ti rods, as could with steel rods....So I guess that means you can't produce an example...so how can you call the solution proven for a 1000rwhp+, street-driven 2jz-gte? Proven for what? 20 passes down the dragstrip? Lol.

...No you didn't "successfully" come up with an alternative and you can't!...So you're saying reducing the rpm does not reduce inertial loads? :rolleyes:

...You haven't shown any data....whatsoever. You crack me up with this stuff...your can't even get your own story straight!Repost (http://www.thesupraforums.com/showpost.php?p=10351&postcount=38):
http://www.eng-tips.com/viewthread.cfm?qid=85349
http://e30m3performance.com/tech_articles/engine-tech/rod-ratio/index.htm
http://e30m3performance.com/tech_articles/engine-tech/rod-ratio/kin2.htm
If side loading the huge, pervasive, primary rpm-limiting factor that you say it is ... something that must keep all engine builders tossing in turning during their sleep every night ... then explain why neither of these discussions on rpm and rod:stroke ratio even mentions it.

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...still waiting for your relevant data on rod angles at rpm limit...

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Again, this whole discussion has regressed to pointless bantering. I've already suggested that we agree to disagree (http://www.thesupraforums.com/showpost.php?p=10070&postcount=11) on this topic. It appears we've both shared our perspectives on this topic, so why drag this on any further?

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So I guess that means you can't produce an example...so how can you call the solution proven for a 1000rwhp+, street-driven 2jz-gte? Proven for what? 20 passes down the dragstrip? Lol.

So you're saying reducing the rpm does not reduce inertial loads? :rolleyes:

Repost (http://www.thesupraforums.com/showpost.php?p=10351&postcount=38):
http://www.eng-tips.com/viewthread.cfm?qid=85349
http://e30m3performance.com/tech_articles/engine-tech/rod-ratio/index.htm
http://e30m3performance.com/tech_articles/engine-tech/rod-ratio/kin2.htm
If side loading the huge, pervasive, primary rpm-limiting factor that you say it is ... something that must keep all engine builders tossing in turning during their sleep every night ... then explain why neither of these discussions on rpm and rod:stroke ratio even mentions it.

______________


...still waiting for your relevant data on rod angles at rpm limit...

______________


Again, this whole discussion has regressed to pointless bantering. I've already suggested that we agree to disagree (http://www.thesupraforums.com/showpost.php?p=10070&postcount=11) on this topic. It appears we've both shared our perspectives on this topic, so why drag this on any further?

______________

Posting someone elses discussion doesn't provide any data of any sort.

Reducing rpm is NOT an alternative solution....reducing rpm reduces power...oh....wait.....you don't care about what the engine wants......

Great.....quit posting! You can disagree all you want for all I care....doesn't make you right. I have handley proved that inertial loads are not a primary or secondary concern when stroking an engine. All you ever came up with was hypothetical situations....that's it.

The stroke of the crank does not determine piston speed or inertial loading. The length of the rod does....you clown. I gave you 2 pages to come up with this on your own...Why don't you do your own research to figure it out....then get back to us...there are several good engine building books out there that discuss proper geometry when building/modifying engines.

Posting someone elses discussion doesn't provide any data of any sort...And what have you posted to support your assertions regarding rod angle at the rev limit?

...Reducing rpm is NOT an alternative solution....reducing rpm reduces power...oh....wait.....you don't care about what the engine wants...You're wrong yet again. If you're past the horsepower peak, reducing rpm does not reduce power.

...Great.....quit posting! You can disagree all you want for all I care....doesn't make you right. I have handley proved that inertial loads are not a primary or secondary concern when stroking an engine. All you ever came up with was hypothetical situations....that's it...Of course you can also disagree that inertial load isn't the primary issue at rpm limit all you want, that doesn't make you right either. The only information you've presented about rod angles is relevant at torque peak, not at the rpm limit.

...The stroke of the crank does not determine piston speed or inertial loading. The length of the rod does....you clown. I gave you 2 pages to come up with this on your own...Why don't you do your own research to figure it out....then get back to us...there are several good engine building books out there that discuss proper geometry when building/modifying engines.Clearly you're the clown in this discussion. At a fixed rpm rate (i.e. a given rev limit), stroke length determines both piston speed and inertial load. If a piston has to travel further in the same amount of time, it's going faster. :eusa_doh: Your grasp of basic engine dynamics seems to be sorely lacking. Apparently you need to take your own advice and read the books you're referring to.

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...still waiting for your relevant data on rod angles at rpm limit...

______________


Again, this whole discussion has regressed to pointless bantering. I've already suggested that we agree to disagree (http://www.thesupraforums.com/showpost.php?p=10070&postcount=11) on this topic. It appears we've both shared our perspectives on this topic, so why drag this on any further?

______________

And what have you posted to support your assertions regarding rod angle at the rev limit?

You're wrong again. If you're past the horsepower peak, reducing rpm does not reduce power.

Wow...not only are you bad with engines, you are bad with basics. Do I really need to enlighten you here??? Ever heard of area under the curve? EVERYONE shifts past the peak power rpm, so when you fall into the next gear....you start at a higher number... my 8 year old daughter understands this concept.

Of course you can also disagree that inertial load isn't the primary issue at rpm limit all you want, that doesn't make you right either. The only information you've presented about rod angles is relevant at torque peak, not at the rpm limit.

Clearly you're the clown in this discussion. At a fixed rpm rate (i.e. a given rev limit), stroke length determines both piston speed and inertial load. Your grasp of basic engine dynamics seems to be sorely lacking.

Sorry (well...not really) but you could not be MORE wrong. If I have a 3"stroke and a 3" rod, you are now trying to tell me that the piston speed and loads are the same as if you have a 3" stroke and a 6" rod??? Go away!

Wow...not only are you bad with engines, you are bad with basics. Do I really need to enlighten you here??? Ever heard of area under the curve? EVERYONE shifts past the peak power rpm, so when you fall into the next gear...Apparently you're as bad with understanding rpm limits as you are with sticking to the truth. You never referred to shifting in your earlier post. You simply said "reducing rpm reduces power", which is not a true statement in general. Even if you consider shifting, there's an ideal shift point ... and if you run the rpm past that point you're slower. Past that ideal shift point, reducing the rpm limit does NOT "reduce power", so your statement is not true in general.
...you start at a higher number... my 8 year old daughter understands this concept...Perhaps you should let her spec your engines...she'd probably do a better job of it.
...Sorry (well...not really) but you could not be MORE wrong. If I have a 3"stroke and a 3" rod, you are now trying to tell me that the piston speed and loads are the same as if you have a 3" stroke and a 6" rod??? Go away!Where do you get these weird examples. I'm saying that all else being equal, piston speed is higher with a 6" stroke than a 3" stroke, at a given rpm point (eg. at the rpm limit). Do you dispute that?

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...still waiting for your relevant data on rod angles at rpm limit...

______________


Again, this whole discussion has regressed to pointless bantering. I've already suggested that we agree to disagree (http://www.thesupraforums.com/showpost.php?p=10070&postcount=11) on this topic. It appears we've both shared our perspectives on this topic, so why drag this on any further?

______________

Apparently you're as bad with understanding rpm limits as you are with sticking to the truth. You never referred to shifting in your earlier post. You simply said "reducing rpm reduces power", which is not a true statement in general.
Perhaps you should let her spec your engines...she'd probably do a better job of it.

You can't comprehend what you write, let alone what I write. So what's the point. If your "reasonable" alternative to the ti rods is to lower the rpm....and that won't "hurt anything" as long as it's after peak hp (never mind the fact it most likely wouldn't be), then quite simply....your solutions is not a solution



Where do you get these weird examples. I'm saying that all else being equal, piston speed is higher with a 6" stroke than a 3" stroke, at a given rpm point (eg. at the rpm limit). Do you dispute that?

The two are related..if the rod length is shorter, piston speed and loads go down....forget it...you lack the ability to comprehend this simple fact.

Why don't you just do this. Call up Kenny Duttweiler, tell him you want to stroke an LS1 from a 350 c.i. motor to a 427 c.i. motor, then ask him what he thinks is the biggest issue with doing that! DO NOT POST AGAIN UNTIL YOU DO THIS.... I won't until I see what you say his response is....ofcourse I doubt you will take his word for it....you would much rather look at forums discussions to find your answers.

You can't comprehend what you write, let alone what I write. So what's the point. If your "reasonable" alternative to the ti rods is to lower the rpm....and that won't "hurt anything" as long as it's after peak hp (never mind the fact it most likely wouldn't be), then quite simply....your solutions is not a solution...For anyone on a fixed engine-building budget, running non-titanium rods at a lower rpm limit most certainly is a practical solution. I honestly doubt you'd find anyone else on this forum to disagree with this.
...The two are related..if the rod length is shorter, piston speed and loads go down....forget it...you lack the ability to comprehend this simple fact...You're the one trying to twist the discussion. This whole thread has nothing to do with shorter rods (directly). It specifically refers to STROKE. Again, read the thread title "Rpm capability and stroked motors". If STROKE is longer, piston speed goes up at a given rpm point/limit, and YOU apparently can't comprehend that FACT.
...Why don't you just do this. Call up Kenny Duttweiler, tell him you want to stroke an LS1 from a 350 c.i. motor to a 427 c.i. motor, then ask him what he thinks is the biggest issue with doing that! DO NOT POST AGAIN UNTIL YOU DO THIS.... I won't until I see what you say his response is....of course I doubt you will take his word for it....you would much rather look at forums discussions to find your answers.Again, it's your turn to provide some data here. Let us know what he says and DO NOT POST AGAIN UNTIL YOU DO THIS. Of course you'd probably rather rely on your false laurels and nut swinging than presenting some real data here.

Btw, comparing 350ci to 427ci displacement is a 22% change (versus an 11% change going from 3.07L (87mm pistons) to 3.4L). Without a radical redesign of the 350 block, I agree that rod angle would likely be an issue at torque peak. At rpm limit, I'm sure he will agree inertial loads is the primary concern. Btw, if you'd like to present a slightly more relevant scenario to your buddy Kenny D., only stroke it up to 390ci.

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...still waiting for your relevant data on rod angles at rpm limit...

______________


Again, this whole discussion has regressed to pointless bantering. I've already suggested that we agree to disagree (http://www.thesupraforums.com/showpost.php?p=10070&postcount=11) on this topic. It appears we've both shared our perspectives on this topic, so why drag this on any further?

______________

For anyone on a fixed engine-building budget, running non-titanium rods at a lower rpm limit most certainly is a practical solution. I honestly doubt you'd find anyone else on this forum to disagree with this.
You're the one trying to twist the discussion.

What does a budget have to do with anything.


This whole thread has nothing to do with shorter rods (directly). It specifically refers to STROKE. Again, read the thread title "Rpm capability and stroked motors".

You can't stroke an engine without changing rod lenghths...unless ofcourse you change your deck height.

If STROKE is longer, piston speed goes up at a given rpm point/limit, and YOU apparently can't comprehend that FACT.

No not necessarily....rod ratio determines this.

Again, it's your turn to provide some data here. Let us know what he says and DO NOT POST AGAIN UNTIL YOU DO THIS. Of course you'd probably rather rely on your false laurels and nut swinging than presenting some real data here.

Btw, comparing 350ci to 427ci displacement is a 22% change (versus a 13% change going from 3.0L to 3.4L). Without a radical redesign of the 350 block, I agree that rod angle would likely be an issue at torque peak. At rpm limit, I'm sure he will agree inertial loads is the primary concern. Btw, if you'd like to present a slightly more relevant scenario to your buddy Kenny D., only stroke it up to 395ci.

I already had this discussion with him.... I know his answer. Even un stroked, the primary concern is rod ratio. Any good engine builder will tell you that.

______________


...still waiting for your relevant data on rod angles at rpm limit...

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Your still waiting for a brain from the wizard......

What does a budget have to do with anything...It has to do with practical real-world solutions to problems and trade offs that our fellow Supra owners face on a regular basis. For some, the cost-benefit of getting 1000 more rpm at the top end, along with a possible risk of limited engine longevity isn't worth the tradeoff. Therefore staying with forged steel rods and lowering the rpm limit a bit is in fact is a practical solution to keeping inertial loads below failure point. Keep your eye on the ball, son.

...You can't stroke an engine without changing rod lenghths...unless ofcourse you change your deck height...So it appears you're finally starting to see that when stroke goes up, so does piston speed, at a given rpm point/limit.

...No not necessarily....rod ratio determines this...Sigh. Rod ratio (http://e30m3performance.com/tech_articles/engine-tech/rod-ratio/index.htm) does not determine whether or not piston speed increases with stroke at a given rpm point/limit. If the stroke is longer, the piston has to travel further. At a given rpm point/limit, that increased distance must be traversed in exactly the same amount of time. Therefore the piston speed goes up. Get it yet?

...I already had this discussion with him.... I know his answer. Even un stroked, the primary concern is rod ratio. Any good engine builder will tell you that...Stick to the topic. We're not talking about primary engine-building concerns, we're talking about "Rpm capability and stroked motors!". Those two topics are related, but they are not precisely the same.

...Your still waiting for a brain from the wizard...At least I'm ahead of you in line. Btw, it's "you're" and not "your".

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...still waiting for your relevant data on rod angles at rpm limit...

______________


Again, this whole discussion has regressed to pointless bantering. I've already suggested that we agree to disagree (http://www.thesupraforums.com/showpost.php?p=10070&postcount=11) on this topic. It appears we've both shared our perspectives on this topic, so why drag this on any further?

______________

It has to do with practical real-world solutions to problems and trade offs that our fellow Supra owners face on a regular basis. For some, the cost-benefit of getting 1000 more rpm at the top end, along with a possible risk of limited engine longevity isn't worth the tradeoff. Therefore staying with forged steel rods and lowering the rpm limit a bit is in fact is a practical solution to keeping inertial loads below failure point. Keep your eye on the ball, son.

I'm glad you agree that when stroke goes up, so does piston speed, at a given rpm point/limit.

Rod ratio (http://e30m3performance.com/tech_articles/engine-tech/rod-ratio/index.htm) does not determine whether or not piston speed increases with stroke at a given rpm point/limit. If the stroke is longer, the piston has to travel further. At a given rpm point/limit, that increased distance must be traversed in exactly the same amount of time. Therefore the piston speed goes up. Get it yet?

Stick to the topic. We're not talking about primary engine-building concerns, we're talking about "Rpm capability and stroked motors!". Those two topics are related, but they are not precisely the same.

At least I'm ahead of you in line. Btw, it's "you're" and not "your".

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...still waiting for your relevant data on rod angles at rpm limit...

______________


Again, this whole discussion has regressed to pointless bantering. I've already suggested that we agree to disagree (http://www.thesupraforums.com/showpost.php?p=10070&postcount=11) on this topic. It appears we've both shared our perspectives on this topic, so why drag this on any further?

______________

You are completely wrong...haven't a clue....Rod ratio is the only determining factor in piston speed. Think of it as a cam the piston accelerates ALOT faster as the crank passes the horizontal plane, and moves toward top dead center. Piston speed on an f1 engine running at 19krpm is slower than a stock ls1 chevy. why? becuase the ROD ratio is much.....much smaller....not becuase the stroke is smaller.

I have forgotten more about engine building in the last two pages, than you will know in your entire life. I'm done! Go build pc's, or take customer service complaints or whatever it is your supervisors think you do.

You are completely wrong...haven't a clue....Rod ratio is the only determining factor in piston speed. Think of it as a cam the piston accelerates ALOT faster as the crank passes the horizontal plane, and moves toward top dead center. Piston speed on an f1 engine running at 19krpm is slower than a stock ls1 chevy. why? becuase the ROD ratio is much.....much smaller....not becuase the stroke is smaller...I agree that last you're finally in the ball park on one small point. However, if the rod length remains constant, stroke IS the primary factor in determining piston speed. ...also note that no one is talking about putting F1 rods into a 2jz-gte. Bottom line is this: if you do the math, the pistons travel faster in a stroked 2jz-gte...therefore built&stroked vs. built&non-stroked (with near equivalent components) you have to deal with higher inertial loads at a given rpm limit in the stroked engine. Period. Seems you feel everyone reading this thread is too clueless to notice your attempt to distract attention away from that key point.

... and don't forget that you still haven't provided any data on why you feel rod angle is more important than inertial loads at rpm limit.
...I have forgotten more about engine building in the last two pages, than you will know in your entire life. I'm done! Go build pc's, or take customer service complaints or whatever it is your supervisors think you do.Again, with weak, the off-base personal attacks. It appears from your unsupportable statements about rod angles at rpm limit that you've fogotten far too much about engine building, so perhaps you should go build PCs or take customer service complaints.

I agree that last you're finally in the ball park on one small point. However, if the rod length remains constant, stroke IS the primary factor in determining piston speed. .

LOL....I was rolling at this one.... we are now back to pwpanas fantasy land! Do you realize that if you stroke a crank....and rod length stays the same.....as you put it....the piston will be driven right through the cylinder head? The rod length HAS TO CHANGE you jackass.



...also note that no one is talking about putting F1 rods into a 2jz-gte. Bottom line is this: if you do the math, the pistons travel faster in a stroked 2jz-gte...therefore built&stroked vs. built&non-stroked (with near equivalent components) you have to deal with higher inertial loads at a given rpm limit in the stroked engine. Period. Seems you feel everyone reading this thread is too clueless to notice your attempt to distract attention away from that key point..

If we are talking directly about 2jz's (which we aren't) the "inertial loads" have no bearing, because the 2j's cylinder head runs out of flow (for the 10th time) waay before the "inertial loads" come in to play....you know...REALITY

LOL....I was rolling at this one.... we are now back to pwpanas fantasy land! Do you realize that if you stroke a crank....and rod length stays the same.....as you put it....the piston will be driven right through the cylinder head? The rod length HAS TO CHANGE you jackass.No rod length does not have to change. Since you say budget isn't a relevant issue (http://www.thesupraforums.com/showpost.php?p=10430&postcount=70), let's go ahead and re-cast the block and extend the cylinders. You're wrong yet again and I guess that makes you the jackass. If you'd concentrate on the problem at hand instead of trying to prove me wrong on every nuance, we might make some progress on this thread.

Again, keep your eye on the ball here. Bottom line is if you do the math, the pistons travel faster in a stroked 2jz-gte (about 16% faster if similar configuration pistons are used)...therefore built&stroked vs. built&non-stroked (with near equivalent components) you have to deal with higher inertial loads at a given rpm limit in the stroked engine. Period.
If we are talking directly about 2jz's (which we aren't) the "inertial loads" have no bearing, because the 2j's cylinder head runs out of flow (for the 10th time) waay before the "inertial loads" come in to play ... you know...REALITYIn REALITY, over-revving in 1st gear (accidentally or on purpose) and exceeding 10K rpm is easy with a 2jz-gte (and no rev limiter, of course). Inertial loads are easily an issue at 10K+. Strike 3 (actually about strike 30) and you're out.


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...still waiting for your relevant data on rod angles at rpm limit...

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Again, this whole discussion has regressed to pointless bantering. I've already suggested that we agree to disagree (http://www.thesupraforums.com/showpost.php?p=10070&postcount=11) on this topic. It appears we've both shared our perspectives on this topic, so why drag this on any further?

______________

No rod length does not have to change. Since you say budget isn't an issue, let's go ahead and re-cast the block and extend the cylinders. You're wrong again and I guess that makes you the jackass. If you'd concentrate on the problem at hand instead of trying to prove me wrong on every nuance, we might make some progress on this thread.

Again, keep your eye on the ball here. Bottom line is if you do the math, the pistons travel faster in a stroked 2jz-gte (almost 20% faster at 30 degrees and 330 degrees, in fact)...therefore built&stroked vs. built&non-stroked (with near equivalent components) you have to deal with higher inertial loads at a given rpm limit in the stroked engine. Period.
REALITY, over-revving in 1st gear (accidentally or on purpose) exceeding 10K is easy with a 2jz-gte and no rev limit. Inertial loads are easily an issue at 10K+. Strike 3 (actually about strike 30) and you're out.


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...still waiting for your relevant data on rod angles at rpm limit...

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Again, this whole discussion has regressed to pointless bantering. I've already suggested that we agree to disagree (http://www.thesupraforums.com/showpost.php?p=10070&postcount=11) on this topic. It appears we've both shared our perspectives on this topic, so why drag this on any further?

______________

Blaaaahhh,Blaaaahhh,Blaaaahhh,Blaaaahhh,Blaaaahhh, Blaaaahhh,Blaaaahhh,Blaaaahhh,Blaaaahhh,Blaaaahhh

Blaaaahhh,Blaaaahhh,Blaaaahhh,Blaaaahhh,Blaaaahhh, Blaaaahhh,Blaaaahhh,Blaaaahhh,Blaaaahhh,BlaaaahhhH ow very clever of you. Did you come up with that response all by yourself, or did you have to phone Kenny Duttweiler again for supporting data?

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...still waiting for your relevant data on rod angles at rpm limit...

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Here's some additional info that an engine builder friend of mine dug up just for you, since you have admittedly (http://www.thesupraforums.com/showpost.php?p=10433&postcount=72) (and obviously) ""forgotten"" :rolleyes: so very much about this topic: Rod length is completely inconsequential to MEAN piston speed, which is the determining factor for any engine designer when he's trying to figure out piston life. Rod length only enters the picture to determine accelerative loading on the little end of the rod.
Total rod weight is essentially irrelevant, because we aren't talking about the crank bearings suffering, only the piston flying off the end of the rod. The whole issue with accelerative loading is with the piston cracking the pin bosses, or the little end of the rod.
Here's another way to keep the same rod length in a stroked engine: Shove the ring pack up as high as it will go, put the pin boss as high as you can in the piston and run the thinnest rings you can get away with and you've got MORE room to push the piston up. Look at the HKS stroker kit for an example.
Damage from excessive inertial loads will happen to any engine that gets over-rev'd ... and the worst part about it is it may NOT fail at the time it over-revs, but some other time later on when you're scratching your head trying to figure out why that rod little end broke, or the pin pulls out of the piston at a very normal speed and load.
Aluminum can only be so strong. Add material to the pin boss and you double screw yourself because now you've added more mass to the acceleration problem.
It's a huge balancing act. If stroke made no difference to redline, why the f_ do F1 engines have such short strokes? It isn't because they couldn't fill the cylinder, it's because the freaking pistons would fly off the ends of the rods if the stroke were any longer.
Longer rods do HELP, but they DON'T solve the inertial loading problem. For example, the piston travels 16% faster than oem in a stroked 2jz-gte with shorter rods. With oem-length rods shoved deep into trick pistons, that same 3.4L stroker is still subjected to a 14% faster than oem piston speed (and the resulting increased inertial loads).
Your statement about rod length is dead ass backwards. Ideal rod/stroke ratio is ~2.2. There isn't a production car engine on the road with rods that long because they won't fit under the hood or between the wheels on a boxer engine.
Lastly if your PC is slow, it's because you're visiting too many porn sites and your box no longer belongs to you; it belongs to the h4x0r5!
:moon:

I don't know if you both realize that you are essentially arguing the same point. But neither of you said the specific reason for both your arguments. The last post you put up (written by someone else) pwpanas said it... Mean piston speed. But there is more to it than just that.

Stroke increases the mean piston speed, but it is the mass of the piston and the rod to stroke ratio that effects whether it lives or grenades. As mass increases, the physical forces on an object increase exponentially. It is not a linear relationship. The old V8 rule of thumb was not to exceed 3700 ft/sec piston speed. But modern small displacement, high RPM engines like a street bike, speeds can be well in excess of 5000 ft/sec. This is because the piston is so much smaller and is so much lighter than a 350cid engine. Increasing the stroke increases the average piston speed. BUT what damages the piston specifically is the rapid deceleration and reacceleration of the piston at TDC and BDC. This relationship is a direct result of (but not limited to) the rod to stroke ratio.

A longer rod will not have a significant effect on the piston speed in the middle of the stroke but will have a drastic effect approaching TDC. This is where the inertia comes into effect and where the durability of the engine is compromised. The lateral loading of the rod is not as big a deal as the loading of the piston skirt on the cylinder. A short rod to stroke ratio will increase the load on the piston and cylinder wall and create high amount of friction. This leads to cracked piston skirts worn cylinder walls etc. The piston will give before the rod will from this effect. Classic 400” chevy small block problem. It had a 1.5 R to S ratio compared to 1.63 of the 350.

This goes into the piston pin comment. It is not always practical or is not always an option to raise the pin in the piston because this means the rings have to be moved up closer to the chamber and heat becomes an issue. This is why TYPICALLY increasing stroke really can be an issue. You don’t always have the ability to put it high enough without increasing the deck height of the motor so a shorter rod is used. Ever wonder why the tall deck big block chevy was the engine of choice in pro stock many years back???? You could run a long rod.

The rod to stroke ratio needs to be tailored to the operating RPM for durability and also for the dwell time at TDC. A longer rod will slow the piston at TDC and allow the flame front to propagate sufficiently. This does work against you at low engine speeds. Too long at high pressures will detonate easily. Notice how knock prone the 2JZ is? It has about a 1:9 R to S ratio and rattles easily at lower engine speeds. Speaking of that, the standard optimum is very debatable. Trends used to be above 1:7 was desired, higher speeds liked higher ratios. 15k RPM Cart engines run about 2.4 to slow the piston for combustion efficiency and for durability. I’ve heard pro stock (VERY heavy pistons) has gone toward 1:6 R to S so they are likely taking advantage of other cylinder filling effects at BDC. Short rods dwell longer at BDC and increase cylinder filling. They only need to last a short time and so the piston can survive. Who knows?

So….. The R to S ratio HAS to be considered for a given RPM as well as concern for piston mass to affect inertia. The rod itself isn’t as much of a consideration to RPM as the other issues. All things the same the longer stroke will increase piston speed but if the rod ratio is considered and optimized better than the original stroke piston mass combination, the longer stroke engine could have higher RPM capability.

It really depends on the application what is ideal and what is a problem. Modern production engines have been on a trend for longer strokes because a large bore creates efficient flame propagation issues. But… stroke has a profound effect on engine friction and bore does not. These engines have different needs than a race engine so again… application.

You are both basically right and arguing the same point. Piston speed.

On a side note I always laugh when the analogy of an ant lifting 4 times its weight is used. If you were that small you could probably lift 2 times your weight.

Hope that helps :aiwebs_01

I don't know if you both realize that you are essentially arguing the same point. But neither of you said the specific reason for both your arguments. The last post you put up (written by someone else) pwpanas said it... Mean piston speed. But there is more to it than just that.

Stroke increases the mean piston speed, but it is the mass of the piston and the rod to stroke ratio that effects whether it lives or grenades. As mass increases, the physical forces on an object increase exponentially. It is not a linear relationship. The old V8 rule of thumb was not to exceed 3700 ft/sec piston speed. But modern small displacement, high RPM engines like a street bike, speeds can be well in excess of 5000 ft/sec. This is because the piston is so much smaller and is so much lighter than a 350cid engine. Increasing the stroke increases the average piston speed. BUT what damages the piston specifically is the rapid deceleration and reacceleration of the piston at TDC and BDC. This relationship is a direct result of (but not limited to) the rod to stroke ratio.

A longer rod will not have a significant effect on the piston speed in the middle of the stroke but will have a drastic effect approaching TDC. This is where the inertia comes into effect and where the durability of the engine is compromised. The lateral loading of the rod is not as big a deal as the loading of the piston skirt on the cylinder. A short rod to stroke ratio will increase the load on the piston and cylinder wall and create high amount of friction. This leads to cracked piston skirts worn cylinder walls etc. The piston will give before the rod will from this effect. Classic 400” chevy small block problem. It had a 1.5 R to S ratio compared to 1.63 of the 350.

This goes into the piston pin comment. It is not always practical or is not always an option to raise the pin in the piston because this means the rings have to be moved up closer to the chamber and heat becomes an issue. This is why TYPICALLY increasing stroke really can be an issue. You don’t always have the ability to put it high enough without increasing the deck height of the motor so a shorter rod is used. Ever wonder why the tall deck big block chevy was the engine of choice in pro stock many years back???? You could run a long rod.

The rod to stroke ratio needs to be tailored to the operating RPM for durability and also for the dwell time at TDC. A longer rod will slow the piston at TDC and allow the flame front to propagate sufficiently. This does work against you at low engine speeds. Too long at high pressures will detonate easily. Notice how knock prone the 2JZ is? It has about a 1:9 R to S ratio and rattles easily at lower engine speeds. Speaking of that, the standard optimum is very debatable. Trends used to be above 1:7 was desired, higher speeds liked higher ratios. 15k RPM Cart engines run about 2.4 to slow the piston for combustion efficiency and for durability. I’ve heard pro stock (VERY heavy pistons) has gone toward 1:6 R to S so they are likely taking advantage of other cylinder filling effects at BDC. Short rods dwell longer at BDC and increase cylinder filling. They only need to last a short time and so the piston can survive. Who knows?

So….. The R to S ratio HAS to be considered for a given RPM as well as concern for piston mass to affect inertia. The rod itself isn’t as much of a consideration to RPM as the other issues. All things the same the longer stroke will increase piston speed but if the rod ratio is considered and optimized better than the original stroke piston mass combination, the longer stroke engine could have higher RPM capability.

It really depends on the application what is ideal and what is a problem. Modern production engines have been on a trend for longer strokes because a large bore creates efficient flame propagation issues. But… stroke has a profound effect on engine friction and bore does not. These engines have different needs than a race engine so again… application.

You are both basically right and arguing the same point. Piston speed...Toyota Dave, many thanks for the supplimental information. Please note however that the crux of our disagreement was about whether increased inertial loads or increased lateral loads are a more important when determining the rev limit of a stroked 2jz-gte (vs a non-stroked, equivalently 'built' 2jz-gte). We can't both be right, since we're each on record stating that one is a much more important issue than the other.

Since the bulk of your supplimental information was about piston speed, one might assume that you also consider piston speed (and the resulting increased inertial loads) to be more of an issue than lateral loading in determining the rpm limit of a stroked 2jz-gte vs a non-stroked (and equivalently 'built') 2jz-gte. If you would confirm (or refute) that assumption that by specifically weighing in (pardon the pun) on the core point of disagreement, I'd very much appreciate it.

Toyota Dave, many thanks for the supplimental information. Please note however that the crux of our disagreement was about whether increased inertial loads or increased lateral loads are a more important when determining the rev limit of a stroked 2jz-gte (vs a non-stroked, equivalently 'built' 2jz-gte). We can't both be right, since we're each on record stating that one is a much more important issue than the other.

Since the bulk of your supplimental information was about piston speed, one might assume that you also consider piston speed (and the resulting increased inertial loads) to be more of an issue than lateral loading in determining the rpm limit of a stroked 2jz-gte vs a non-stroked (and equivalently 'built') 2jz-gte. If you would confirm (or refute) that assumption that by specifically weighing in (pardon the pun) on the core point of disagreement, I'd very much appreciate it.

Dave is on the money.....piston speed and inertial loads are two completely different considerations. Clearly from his post.. and your buddies....rod to stroke ratio is the Primary concern (essentially what I was saying). Bottom line the inertial loads are NOT the primary concern.....as I said! Don't try and change the argument point. You said it was a primary concern....I listed 7 other considerations, and stated that the rod angle and rod ratio were more critical considerations.

Dave is on the money.....piston speed and inertial loads are two completely different considerations. Clearly from his post.. and your buddies....rod to stroke ratio is the Primary concern (essentially what I was saying). Bottom line the inertial loads are NOT the primary concern.....as I said! Don't try and change the argument point. You said it was a primary concern....I listed 7 other considerations, and stated that the rod angle and rod ratio were more critical considerations.Actually what you said was that rod angle (aka lateral loading) is the primary concern, and not "rod ratio". I'm certain that is crystal-clear to everyone that's been following this thread. You're the one that's trying to change the argument point now, because you're beginning to realize that you're dead wrong.

Here's your exact quote (http://www.thesupraforums.com/showpost.php?p=10176&postcount=28) (qft):
...So...since the first thing that becomes a problem is rod angle, which starts to be a problem as soon as cylinder pressure starts increasing, and just gets worse as rpm goes up. This would be your primary concern, becuase it becomes an issue much sooner than any rotating mass does...
...so junior, why don't you just sit the f_ back and let the man respond...or are you scared of what he'll say?

Actually what you said was that rod angle (aka lateral loading) is the primary concern, and not "rod ratio". I'm certain that is crystal-clear to everyone that's been following this thread. You're the one that's trying to change the argument point now, because you're beginning to realize that you're dead wrong.

Here's your exact quote (http://www.thesupraforums.com/showpost.php?p=10176&postcount=28) (qft):

...so junior, why don't you just sit the f_ back and let the man respond...or are you scared of what he'll say?


What do you think rod angle is related to...genious?

The POINT is...Inertial load is NOT a PRIMARY CONCERN.....NOT.....A.....PRIMARY.....CONCERN!

Here is what you said.

a stroker will have significantly higher inertial loads,and that's the primary rev-limiting factor. In order to avoid damage due to those higher inertial loads, the rpm limit must be decreased OR components must be swapped.

What do you think rod angle is related to...genious?The context in which you brought up rod angle referred to side/lateral loading, NOT piston speed changes (and the resulting increased inertial loads) due to rod ratio...or are you going to claim you can no longer understand the posts that you wrote earlier in this thread?
...The POINT is...Inertial load is NOT a PRIMARY CONCERN.....NOT.....A.....PRIMARY.....CONCERN!Yes, yes, we know what that's what you've deluded yourself to believe. Now let's hear what Toyota Dave has to say about it. Honestly I'm tired of hearing about your erroneous OPINION about what primarily limits max rpm in a stroked 2jz vs. a non-stroked 2jz, and I'm sure everyone else is too.
...Here is what you said.
a stroker will have significantly higher inertial loads,and that's the primary rev-limiting factor. In order to avoid damage due to those higher inertial loads, the rpm limit must be decreased OR components must be swapped.Of course that's what I said. And it's STILL true; the laws of physics don't change just because this thread has gone to a new page. :rolleyes:

Again, stfu and let the man respond.

The context in which you brought up rod angle referred to side/lateral loading, NOT piston speed changes (and the resulting increased inertial loads) due to rod ratio...or are you going to claim you can no longer understand the posts that you wrote earlier in this thread?
Yes, yes, we know what that's what you've deluded yourself to believe. Now let's hear what Toyota Dave has to say about it. Honestly I'm tired of hearing about your erroneous OPINION about what primarily limits max rpm in a stroked 2jz vs. a non-stroked 2jz, and I'm sure everyone else is too.
Of course that's what I said. And it's STILL true; the laws of physics don't change just because this thread has gone to a new page. :rolleyes:

Again, stfu and let the man respond.

This whole thing has gone round and round, and waaayyy off track of the inital point. The initial question of why does the rpm limit have to decrease just because an engine is stroked. Your response was that the Inertial loading was your primary concern....it isn't as Dave and your buddy have pointed out. I have pointed out several other concerns that must be considered in front of the end result of "inertial loads". CLEARLY Making it a secondary issue. All you have done is made a statement, with no real understanding of what point you were trying to make. You think this is about you..it isn't these threads were meant to help the rest of the memebers answer their own questions or inform them of other important issues.


Let us not forget the first thing you mentioned, and my VERY FIRST RESPONSE
Increase in distance traveled per rev, which increases inertial loads.

Me
You mean piston speed!....your getting there...what else?.

Inertial loads have to do with weight not necessarily speed. While they are directly tied together, I can run a lower speed and still have the same inertial loads.


As the 2jz is concerned, you order of concern would be as follows

1) Will the rotating assembly clear the block
2) Is the valvetrain capable of operating at the desired rpm
3) Is your Intake and exhaust up to the flow at desired rpm
4) Is the Geometry of the rotating assembly acceptable for the desired rpm
5) Are the components up to supporting the loads at the desired rpm.

Omg, it's 1BADSUPRA 'up to bat' again. :rolleyes: Here we go...he steps up to the plate:
This whole thing has gone round and round, and waaayyy off track of the inital point. The initial question of why does the rpm limit have to decrease just because an engine is stroked. Your response was that the Inertial loading was your primary concern....it isn't as Dave and your buddy have pointed out...Dave and my buddy pointed out why YOU are wrong, and why a stroker's increased piston speed (and the resulting increased inertial load) is the primary rev limiting concern. Strike one.
...I have pointed out several other concerns that must be considered in front of the end result of "inertial loads". CLEARLY Making it a secondary issue. All you have done is made a statement, with no real understanding of what point you were trying to make. You think this is about you..it isn't these threads were meant to help the rest of the memebers answer their own questions or inform them of other important issues...Of course it's about informing the other members of this board, and making sure they don't do something idiotic like set the rev limit of a stroked engine based on rod angles. Strike two.

As the 2jz is concerned, you order of concern would be as follows

1) Will the rotating assembly clear the block
2) Is the valvetrain capable of operating at the desired rpm
3) Is your Intake and exhaust up to the flow at desired rpm
4) Is the Geometry of the rotating assembly acceptable for the desired rpm
5) Are the components up to supporting the loads at the desired rpm."1)" has nothing specifically to do with rev limit. "2)" has nothing to do with whether or not you're running a stroker. "3)" is load dependent and not the primary concern when setting an absolute rpm limit. "4)" is most important at torque peak and not rpm limit. and "5)" is THE PRIMARY FACTOR, since the critical loads you're referring to that components have to support at peak rpm are INERTIAL loads. Strike three and you're out (again).

You:
You mean piston speed!....your getting there...what else?Me:
You're correct that when I said "Increase in distance traveled per rev..." ALSO means that the speed of the entire piston-and-rod assembly increases...the speed of the piston, the wrist pin, the piston rings, the connecting rod, etc...since (with a stroker kit) you're increasing the distance traveled in the same amount of time...Strike four? Lol.

...Inertial loads have to do with weight not necessarily speed. While they are directly tied together, I can run a lower speed and still have the same inertial loads...For the first time, maybe you're actually seeing the light. So what follows is that if you run a higher rpm with same weight, you have higher inertial loads...which will damage components at a high enough rpm. This is why rpm has to be limited based on inertial loads (and no, it has nothing at all to do with the rod angles that you're so fond of).


It's starting to appears that you really don't care what Toyota Dave has to say on this topic. For God's sake, stfu and wait for his response.

"1)" has nothing specifically to do with rev limit. "2)" has nothing to do with whether or not you're running a stroker. "3)" is load dependent and not the primary concern when setting an absolute rpm limit. "4)" is most important at torque peak and not rpm limit. and "5)" is THE PRIMARY FACTOR, since the critical loads you're referring to that components have to support at peak rpm are INERTIAL loads. Strike three and you're out (again).

.

1) your an idiot- If it doesn't clear the block, you won't get even 1 rpm out of the motor
2) Sure it does, if the top end will only flow to 7k....doesn't matter what the bottom end will do beyond that.
3) Load dependent??? You mean airflow dependent, again if it doesn't flow up there doesn't matter.
4) The Geometry is EVERYTHING to do with the rotating assembly, and is important before you even start the engine!
5) And Bingo Inertial loads....in a sense....but still number 5...not number 1!

I love how you cator statements to your needs when they suite you, but completely contradict the exact same points when they don't.

1) your an idiot- If it doesn't clear the block, you won't get even 1 rpm out of the motor...Only a bigger idiot would design, build and sell a stroker kit that doesn't clear the block. Let's stick to issues on this side of fantasy land, ok Frodo? (I hear you're a chubby little fellow too :lol: )
...2) Sure it does, if the top end will only flow to 7k....doesn't matter what the bottom end will do beyond that....Get this straight once and for all. When we install a stroker, we're not changing the head. This is about what limits rpm in a stroked (vs. non stroked) engine. The head is an independent consideration, and therefore irrelevant to this discussion.
...3) Load dependent??? You mean airflow dependent, again if it doesn't flow up there doesn't matter...Airflow/intake/exhaust are not directly related to rev limit. Again, it's very easy to rev past 10K in 1st gear, either accidentally or on purpose. The lowered rev limit of a stroker protects against inertial damage by not allowing it to over-rev. Again, this has nothing to do with airflow capabilities of the head, it has to do with what limits rpm in a stroker vs a non-stroker.
...4) The Geometry is EVERYTHING to do with the rotating assembly, and is important before you even start the engine!...Quit trying to digress. This thread isn't about starting difficulties, it's about what limits max rpm in a stroker (vs a non-stroker). Focus Frodo, ...focus.
...5) And Bingo Inertial loads....in a sense....but still number 5...not number 1!...Wrong again...it's #1 after we get through with the meaningless drivel that you spewed out for your #1-#4.
...I love how you cator statements to your needs when they suite you, but completely contradict the exact same points when they don't.You've yet to show one contradiction in my points, just as you've yet to produce one shred of evidence that rod angles are more relevant at rpm limit in a stroked vs. non-stroked engine.

Only a bigger idiot would design, build and sell a stroker kit that doesn't clear the block. Let's stick to issues on this side of fantasy land, ok Frodo? (I hear you're a chubby little fellow)
Get this straight once and for all. When we install a stroker, we're not changing the head. This is about what limits rpm in a stroked (vs. non stroked) engine. The head is an independent consideration, and therefore irrelevant to this discussion.
Airflow/intake/exhaust are not directly related to rev limit. Again, it's very easy to rev past 10K in 1st gear, either accidentally or on purpose. The lowered rev limit of as stroker protects against inertial damage by not allowing it to over-rev. Again, this has nothing to do with airflow capabilities of the head, it has to do with what limits rpm in a stroker vs a non-stroker.
Quit trying to digress. This thread isn't about starting difficulties, it's about what limits max rpm in a stroker (vs a non-stroker). Focus Frodo, ...focus.
Wrong again...it's #1 after we get through with the meaningless drivel that you spewed out for your #1-#4.
You've yet to show one contradiction in my points, just as you've yet to produce one shred of evidence that rod angles are more relevant at rpm limit in a stroked vs. non-stroked engine.


You might want to call HKS....you have to clearance the block to install their kit.....guess you don't know as much about all this stuff as you thought ehhh.

You need to get this straight...the Geometry defines everything that goes on with piston speed, rod to stroke ratio, inertial loads, rod angle...that is all the geometry!

You might want to call HKS....you have to clearance the block to install their kit.....guess you don't know as much about all this stuff as you thought ehhh...And that's a relevant point to this whole rpm limit discussion exactly how? Your transparent attempts to digress only serve to highlight your ignorance.

...You need to get this straight...the Geometry defines everything that goes on with piston speed, rod to stroke ratio, inertial loads, rod angle...that is all the geometry!...No, what YOU need to NOTICE is the fact that your posts are referring to INERTIAL LOADS more and more frequently now! Are you trying to say that when you were talking about rod angles for the past bazillion posts you actualy meant to say inertial loads? Roflmao. Is there an echo in here?

First of all we need to keep the personal statements out of this. This has gone from a 2JZ specific debate to a generalities debate than back again. In the process each others point has lost and gained meeting depending on which each is referring too. To summarize the best I can.

General statements I think we all agree on.
1) Stroke increases piston speed.
2) Inertial loads are created and defined by Mass AND Speed (F=MA cannot be debated)
3) RPM potential of a modified OEM production engine starts with the valvetrain capablilities. Remember this is a general statement. To emphisize, whether the valve follows the cam is relationship between the inertial loads of the valve, retainer, bucket or rocker etc cam acceleration/deceleration profile and the springs pressure and jounce charateristics. A lighter valve assembly will require less spring due to reduced inertial loads. (Okay note the parallel to the debate here. 2 elements... mass as it relates to inertia ie: piston speed and cam profile ie: rod/stroke relationship.
4) Induction capability. Honestly in my opinion irrelevant to this discussion because it will continue to rev to the moon, it just won't make any power.
5) As rod length increases the accel/decel of the piston at TDC decreases.
6) As rod length increases the rod angularity decreases reducing lateral load on the piston and cylinder.

Agreed?

Now the original discussion (as I see it) related to the 2JZ SPECIFICALLY:
-Jason says for this application (re-read that please) there are more things to be worried about before you care about piston speed. I tend to agree.
-Pwpanas feels Inertia of the components is the primary concern regarding RPM potential. I also agree assuming the other areas are addressed and optimized if you build 2 identical engines with the difference being stroke only.

This is why I say both are correct. I also think both agree on the physical effects on each components in relation to RPM. In general piston speed is what matters when it comes to RPM if the bore and stroke of 2 same displacement engines is the same. For the 2JZ it there are bigger issues. So its a matter of ALL the variables. I will say rod angle to me is lower on the priority above exceeding piston speeds.

You are both brillant and retarded. : )

Dave, thanks for your sage input.

...General statements I think we all agree on.
1) Stroke increases piston speed.
2) Inertial loads are created and defined by Mass AND Speed (F=MA cannot be debated)
3) RPM potential of a modified OEM production engine starts with the valvetrain capablilities. Remember this is a general statement. To emphisize, whether the valve follows the cam is relationship between the inertial loads of the valve, retainer, bucket or rocker etc cam acceleration/deceleration profile and the springs pressure and jounce charateristics. A lighter valve assembly will require less spring due to reduced inertial loads. (Okay note the parallel to the debate here. 2 elements... mass as it relates to inertia ie: piston speed and cam profile ie: rod/stroke relationship.
4) Induction capability. Honestly in my opinion irrelevant to this discussion because it will continue to rev to the moon, it just won't make any power.
5) As rod length increases the accel/decel of the piston at TDC decreases.
6) As rod length increases the rod angularity decreases reducing lateral load on the piston and cylinder.

Agreed?...Yup, excepting that #3 is not directly relevant to a stroked vs non-stroked discussion.

...Pwpanas feels Inertia of the components is the primary concern regarding RPM potential. I also agree assuming the other areas are addressed and optimized if you build 2 identical engines with the difference being stroke only...Since this thread is about the most important factors at max rpm in stroked (vs non stroked) motors, I very much appreciate your confirmation.
Jason says for this application (re-read that please) there are more things to be worried about before you care about piston speed. I tend to agree...I do too, in general. However the title of this thread is not "General worries for this application" ... it's about rpm limits in a stroked 2jz (vs. non-stroked), and specifically what is the primary factor at that limit. Within the context of this thread (re-read that please), Jason's 'list' of what's important is still dead wrong, imo.

Once again, thanks for your contributions to this thread (except the "retarded" comment ;) ).


______________


1BADSUPRA, Toyota Dave has declared the debate a draw. I'm willing to live with that...are you? ...or will you insist on dragging this out with more pointless bantering?

______________

So...Dave Since Rod angle is DIRECTLY related to rod to stroke ratio or should I say dictated...maybe... would you then consider that a concern before inertial loads....which...are really never a concern since you can always build a stronger component to replace the one that failed becuase of the load that was placed on it? As it pertains to this debate, it was about what is the PRIMARY concern... which as you stated...you tend to agree that it is not your primary concern.

Secondly...while we are at it, would you consider Titanium rods an excellent solution for use in a very high horsepower street driven supra?

Thanks for your input... atleast your weren't just repeating some information stated to you without showing that you understand what's going on!:)

And that's a relevant point to this whole rpm limit discussion exactly how? Your transparent attempts to digress only serve to highlight your ignorance.?

How quickly you forget.....you JUST stated that "Only a bigger idiot would design, build and sell a stroker kit that doesn't clear the block." You following this with any retention...or do you just want to continue trying to reverse and redirect the discussion??????

No, what YOU need to NOTICE is the fact that your posts are referring to INERTIAL LOADS more and more frequently now! Are you trying to say that when you were talking about rod angles for the past bazillion posts you actualy meant to say inertial loads? Roflmao. Is there an echo in here?

No.....i'm not.....rod angle is DIRECTLY related to rod/stroke ratio, so ultimately DETERMINES piston speed...you know....the thing I originally assumed you were talking about until you said "no, I don't mean piston speed....I mean inertial loads" Remember????

More pointless bantering, as initiated by 1BADSUPRA:
How quickly you forget.....you JUST stated that "Only a bigger idiot would design, build and sell a stroker kit that doesn't clear the block." You following this with any retention...or do you just want to continue trying to reverse and redirect the discussion??????...Are you saying that the HKS Stroker kit does not clear any 2jz-gte block? Didn't think so. Lol. And this point still has nothing to do with rpm limit, Frodo.

...No.....i'm not.....rod angle is DIRECTLY related to rod/stroke ratio, so ultimately DETERMINES piston speed...you know....the thing I originally assumed you were talking about until you said "no, I don't mean piston speed....I mean inertial loads" Remember????Again, that's not what I said. I said that increased piston speed (http://www.thesupraforums.com/showpost.php?p=9999&postcount=27) ALSO means increased inertial loads (http://www.thesupraforums.com/showpost.php?p=9989&postcount=25). Can't you read?

More pointless bantering, as initiated by 1BADSUPRA:
Are you saying that the HKS Stroker kit does not clear any 2jz-gte block? Didn't think so. Lol. And this point still has nothing to do with rpm limit, Frodo.?

That is EXACTLY what I am saying....you HAVE TO CLEARANCE THE BLOCK....does that help you understand???

Again, that's not what I said. I said that increased piston speed (http://www.thesupraforums.com/showpost.php?p=9999&postcount=27) ALSO means increased inertial loads (http://www.thesupraforums.com/showpost.php?p=9989&postcount=25). Can't you read?

Saying inertial loading and saying piston speed are not the same thing. The wrist pin has weight, the Rod has weight.....speed kills......is going 100mph in a 360 Ferrari, the same as going 100mph in a 1967 chevy truck? As far as speed....yes...but does that mean that they can both stop and maneuver the same...no......blanket statements based upon something you CLEARLY don't understand don't cut it. The inertial load doesn't mean anything if the components can take it....therefore.....not a PRIMARY concern!

More pointless bantering, as initiated by 1BADSUPRA:

That is EXACTLY what I am saying....you HAVE TO CLEARANCE THE BLOCK...Aside from minor inner block machining that may or may not be required, the HKS Stroker kit generally clears the 2jz-gte block just fine. Since the HKS stroker kit fits, the only "bigger idiot" in this discussion is you for bringing this point up. In addition, getting into trivial installation steps in a high level discussion like this is rather inappropriate. Most importantly however, note that this is NOT a concern directly related specifically to max rpm! The thread title is "Rpm capability and stroked motors!", not "stroker kit install trivialities". Why is that so hard for you to understand?

...Saying inertial loading and saying piston speed are not the same thing. The wrist pin has weight, the Rod has weight.....speed kills......is going 100mph in a 360 Ferrari, the same as going 100mph in a 1967 chevy truck? As far as speed....yes...but does that mean that they can both stop and maneuver the same...no......blanket statements based upon something you CLEARLY don't understand don't cut it. The inertial load doesn't mean anything if the components can take it....therefore.....not a PRIMARY concern!Are you pretending to be an idiot Frodo, or are you really? Your blanket statement that the "components can take it" is boarderline insanity:
1) No matter how strong and light the components, there is an rpm point where the system will break.
2) No matter which strong and light components you put into a stroker, you can put those same components into a non-stroker ... the difference being that in a stroker, those components will be travelling FASTER for a given RPM (leading of course to higher inertial loads in the stroker). Inertial loading will ALWAYS be the primary concern at rpm limit.

So...Dave Since Rod angle is DIRECTLY related to rod to stroke ratio or should I say dictated...maybe... would you then consider that a concern before inertial loads....which...are really never a concern since you can always build a stronger component to replace the one that failed becuase of the load that was placed on it? As it pertains to this debate, it was about what is the PRIMARY concern... which as you stated...you tend to agree that it is not your primary concern.

That is a never ending statement because I would not spend say 50k on a piston that could survive anything in place of changing another aspect of design to avoid it. Again we are talking about a specific engine. At the same time depending what I was after, I might give up some angularity to pick up power by increasing dwell at BDC. I personally would be more concerned with the R to S ratio as it relates to BOTH piston speed at TDC and side loading. If I increased inertial load on the piston due to stroke, I would be damn sure to soften the TDC effects with R to S.

Secondly...while we are at it, would you consider Titanium rods an excellent solution for use in a very high horsepower street driven supra?

Sure! Light weight with good strength goes back to inertia. That is the balance. As light as you can but with the necessary strength.

Thanks for your input... atleast your weren't just repeating some information stated to you without showing that you understand what's going on!:)

Be nice, stop bashing it discredits your opinion. You are a very helpful and generous person but doesn't come across that way in your posts.

You need to at least acknowledge pnpanas (what the hell does that stand for anyway?) concern for inertia effects in this discussion. I KNOW you don't feel it is your primary concern as there is more than one concern depending on application. I know we are talking about the 2JZ and honestly don't think either of your concerns are primary overall when it comes to this engine. I think there are many more induction related issues that come into effect way before either issues cause failure. It think that is why your original statements indicating Saads engine's mass at 10k is not really different than the 3.4 at 10k?

When it comes to stroke in any engine, piston speed is the glaring issue on the table. Now how it is dealt with regarding correct engine design which includes geometry, lies in the correctly optimized rod to stroke ratio. Again how both of you have similar points.

Stop trying to claim a who's right and who's wrong because you essentially are arguing similar and crutial design points that have various solutions dependant on materials and money. It comes down to cost effective compromise and the minimum necessary for durability. LET IT GO!

More pointless bantering, as initiated by 1BADSUPRA:

Aside from minor inner block machining that may or may not be required, the HKS Stroker kit fits the 2jz-gte block and oem deck height just fine. Since the HKS stroker kit fits, the only "bigger idiot" in this discussion is you for bringing it up. In addition, getting into trivial installation steps in a high level discussion like this is rather inappropriate. Most importantly however, note that this is NOT a concern directly related specifically to max rpm! Why is that so hard for you to understand?

Are you pretending to be an idiot Frodo, or are you really? Your blanket statement that the "components can take it" is boarderline insanity:
1) No matter how strong and light the components, there is an rpm point where the system will break.
2) No matter which strong and light components you put into a stroker, you can put those same components into a non-stroker ... the difference being that in a stroker, those components will be travelling FASTER for a given RPM (leading of course to higher inertial loads in the stroker). Inertial loading will ALWAYS be the primary concern at rpm limit.

And there it is...As Dave stated his primary concern was piston speed, and would address it with Rod to stroke ratio....which DIRECTLY relates to rod angle as well. Also as Dave pointed out that wouldn't even be a concern of his becuase with the 2jz (not some hypothetical situation) it is NOT a concern as you will surpass the capabilities of the head flow...as I stated dozens of times before. So I will stick with what I know, the opinions of people like JC (one of the best engine builders in the country, and happens to sit about 50 yards from me) and what Dave has already confirmed twice now. O.K. Smeagel!

Insert Ryan Woon video here.... : )

More pointless bantering, as initiated by 1BADSUPRA:

And there it is...As Dave stated his primary concern was piston speed, and would address it with Rod to stroke ratio....which DIRECTLY relates to rod angle as well...You're missing the point AGAIN, Frodo. Regardless of how much you TRY to minimize the increase in piston speed in a stroker by fiddling with R:S, you'll ALWAYS end up with a faster piston speed for a given rate of rpm (compared with the non-stroked, but otherwise equivalent engine). This means that regardless of the specific R:S, a stroked 2jz-gte's increased INERTIAL LOADS are STILL the primary concern when determining max rpm limit.

...Also as Dave pointed out that wouldn't even be a concern of his becuase with the 2jz (not some hypothetical situation) it is NOT a concern as you will surpass the capabilities of the head flow...as I stated dozens of times before...The rpm limit is ALWAYS a concern in EVERY application. Run without an rpm limit and you risk pulling the steel wrist pin right through the forged aluminum piston if you miss a shift (due to excessive inertial loads, of course).

...So I will stick with what I know, the opinions of people like JC (one of the best engine builders in the country, and happens to sit about 50 yards from me) and what Dave has already confirmed twice now. O.K. Smeagel!So what's your plan? ...to eventually absorb engine building fundamentals from JC via osmosis? If he's already tried to educate you, he's either a far better engine builder than he is a teacher, or you're a terrible student.



______________


Again Frodo, as per Toyota Dave's statements, I'm still willing to offer you a draw in this debate (despite how little you deserve it). If you had an ounce of decorum in your pudgy little hobbit body, you'd take the offer ... so this thread can have it's long overdue death. Deal? ...or will you insist on dragging this out with more futile squabbling?

______________

More pointless bantering, as initiated by 1BADSUPRA:

You're missing the point AGAIN, Frodo. Regardless of how much you TRY to minimize the increase in piston speed in a stroker by fiddling with R:S, you'll ALWAYS end up with a faster piston speed for a given rate of rpm (compared with the non-stroked, but otherwise equivalent engine). This means that regardless of the specific R:S, a stroked 2jz-gte's increased INERTIAL LOADS are STILL the primary concern when determining max rpm limit.

The rpm limit is ALWAYS a concern in EVERY application. Run without an rpm limit and you risk pulling the steel wrist pin right through the forged aluminum piston if you miss a shift (due to excessive inertial loads, of course).

So what's your plan? ...to eventually absorb engine building fundamentals from JC via osmosis? If he's already tried to educate you, he's either a far better engine builder than he is a teacher, or you're a terrible student.



______________


Again Frodo, as per Toyota Dave's statements, I'm still willing to offer you a draw in this debate (despite how little you deserve it). If you had an ounce of decorum in your pudgy little hobbit body, you'd take the offer ... so this thread can have it's long overdue death. Deal? ...or will you insist on dragging this out with more futile squabbling?

______________

Not a concern because it is not an issue...in order for it to be an issue, you would have to run the engine well beyond it's design limitations.....face it. Your just a sore loser...go away.

Not a concern because it is not an issue...in order for it to be an issue, you would have to run the engine well beyond it's design limitations.....face it. Your just a sore loser...go away.Hahahaha. First of all Frodo, you're the looser as it relates to the topic of this thread (as per Toyota Dave). Secondly, that's what over-revving is ... revving beyond design limitiations ... which is exactly why rev limiters exist, to protect against over-revving! Time for you to give this one up. :getout:

Hahahaha. First of all Frodo, you're the looser as it relates to the topic of this thread (as per Toyota Dave). Secondly, that's what over-revving is ... revving beyond design limitiations ... which is exactly why rev limiters exist, to protect against over-revving! Time for you to give this one up. :getout:

Oh god.....here
3+1=4
2+2=4
4+0=4

That should keep you busy for a few months.

You know I just figured something out as I have become quite amused with this thread... The first 4 or 5 post say it all. Jason you posted an question asking what is the primary concern regarding RPM potential of a stroked engine.

pnp replyed stating all things considered and in general (in bold text) inertial loads are because of increases in piston speed as a direct relationship of stroke.

You replyed saying not necessarily because it is really a function of the entire system and assuming the components are of sufficent strength for their mass. Therefore rod geometry is the primary factor.

Well if you take away almost all the other variables as there are many, (and you were the one who made that statement BTW), the only thing left can be considered primary. And since there are many ways to solve such problems, it is unreasonable to automatically discount all the other factors just to get to what you consider primary.

So that is an unfair comparison. It is a whole system approach. If you stroke an engine piston speed increases. It is not the piston speed itself that causes the issue it is the rapid change of direction at TDC. This is addressed with rod length. What is being addressed is inertial loads on the piston.

If you want to look at it as assuming the other parts can take the loading, then the rod geometry is the next consideration. Then you are correct providing your restrictions. However, the piston is generally much weaker than the rod when it comes to side loading and it is not as big a deal as what it does to the piston regarding stopping and starting (which is inertia). By those rules you are right as I know you understand all those other factors well.

Conversely if you want to generalize the issues related to stroke (same everything, rod, piston, journal diameters, etc taller deck for the stroked motor, fully optimized valvetrain, and airflow system) Inertial load due to the higher piston speed as it relates to the piston now having to slow down faster and reaccelerate faster is the determining factor. By that, pnp has you dead to rights.

The problem is the answer you were looking for was assuming those components were more than up to the task for this application and the next step to consider had to do with the rod geometry.

You should have been at dinner tonight with JC, me, and George formerly of Sonny's Racing Engines (Pro Stock/Pro Mod) we all agree there is not one set answer as it has too many factors to just generalize although it all related to inertia of the various components.

You MUST have been busy coming up with that. No wonder your perspective on inertial loads is so badly off...you can't even add! Lol.


The fact you can't do simple addition explains alot. So let's walk through this. You see, in simple addition it is quite easy to solve for a single missing number...for example 3 + x = 5....x=2....simple...or 3+2 = x....x=5...again...simple. When trying to figure out more complicated math scenarios you can't come up with a, or b...just by knowing c. So...

1) you have absolutely no way of knowing what your inertial loads are without first knowing your rod to stroke ratio (rod angle), weight of the piston, wrist pin, rings, rod, rod bolts, crank, etc.... So there is absolutely no way you can address your inertial loads...let alone know what they are, without first knowing the rest of the information. Therefore it quite simply CAN NOT be a PRIMARY concern, at best it would be secondary, as it is not a physical component, only a result. It would be like trying to address a missfire without first addressing the ignition system. Can't be done...period!

Bad example...Who says a misfire can only be an ignition issue? You start with the most LIKELY cause depending on the conditions of a misfire.

Well actually you can calculate it and easily calculate piston speed. But it is more of a rule of thumb/experience situation. At a given stroke, you have to consider how long of a rod you have to run to be on the safe side of piston return load (inertia) and rod angularity. And rod angle is not always the primary concern when you speak of rod length. Stop getting so hung up on the need for a primary concern as many things need to be considered.

I know how you thinks so don't say the first thing you do is always a primary concern because you can start anywhere and rod angle is certainly not always a primary consideration overall because the first thing to always consider is evaluating what is likely your weakest and most stressed component. It could be your block, or mains etc.

You are trying to argue symantics based on both generalities and specific conditions (at the same time). Its not practical to do so.

Bad example...Who says a misfire can only be an ignition issue? You start with the most LIKELY cause depending on the conditions of a misfire..

No....this is a perfect example...who says the piston coming apart is being cause by "inertial forces" that's the whole point.... But if you have absolutely no idea if it will be a problem....it's pretty hard to address anything.



Well actually you can calculate it and easily calculate piston speed. But it is more of a rule of thumb/experience situation. At a given stroke, you have to consider how long of a rod you have to run to be on the safe side of piston return load (inertia) and rod angularity. And rod angle is not always the primary concern when you speak of rod length. Stop getting so hung up on the need for a primary concern as many things need to be considered..

You can't very well calculate the speed without the other info.... PAY ATTENTION HERE.....PWPANAS' statement was that it is ALWAYS a PRIMARY concern.....get it.....that is the point that is being debated.....that it isn't the primary concern at all....the other components will ALWAYS come before you have to consider the end result.


I know how you thinks so don't say the first thing you do is always a primary concern because you can start anywhere and rod angle is certainly not always a primary consideration overall because the first thing to always consider is evaluating what is likely your weakest and most stressed component. It could be your block, or mains etc.

You are trying to argue symantics based on both generalities and specific conditions (at the same time). Its not practical to do so.

Thanks again for proving my point for the third time now.... I never said rod angle was ALWAYS the primary concern. I said it is one of the first things I would look at, amongst other things...you still don't address the end result...you address the components that lead up to them.

you're gay. meet me for lunch at inka

Whats inka?

Where in SoCal are you from Toyota Dave? How quick & fast does your Supra go?

More pointless bantering, as initiated by 1BADSUPRA:
...1) you have absolutely no way of knowing what your inertial loads are without first knowing your rod to stroke ratio (rod angle), weight of the piston, wrist pin, rings, rod, rod bolts, crank, etc.... So there is absolutely no way you can address your inertial loads...let alone know what they are, without first knowing the rest of the information. Therefore it quite simply CAN NOT be a PRIMARY concern, at best it would be secondary, as it is not a physical component, only a result. It would be like trying to address a missfire without first addressing the ignition system. Can't be done...period!Partially correct. Since you absolutely know for a fact that inertial loads are higher in a stroker, that is your primary concern. On the other hand, you don't know precisely how much higher the inertial loads are without all of the supporting data, such as rod and stroke length...so therefore you don't know precisely how much lower to set your rev limit in the stroker without the data that would also allow you to calculate rod angles. That said, the REASON you need those measurements is to deal with the primary concern: increased inertial loads.

No....this is a perfect example...who says the piston coming apart is being cause by "inertial forces" that's the whole point.... But if you have absolutely no idea if it will be a problem....it's pretty hard to address anything...Wrong. At max RPM in a built&stroked 2jz (vs. a non stroked equivalently built 2jz) greater inertial loads will ALWAYS be a problem...and the primary one at that.

...You can't very well calculate the speed without the other info.... PAY ATTENTION HERE.....PWPANAS' statement was that it is ALWAYS a PRIMARY concern.....get it.....that is the point that is being debated.....that it isn't the primary concern at all....the other components will ALWAYS come before you have to consider the end result....Quit trying to take this out of context. We're talking about a built&stroked 2jz at it's rpm limit here. Sure, you can't calculate the precise increase in piston speed without all supporting data, BUT you do know 100% for sure the stroked 2jz will have a significantly higher piston speed than the non-stroked 2jz at a given rate of rpm (which results in higher inertial loads for the stroker).

...Thanks again for proving my point for the third time now.... I never said rod angle was ALWAYS the primary concern. I said it is one of the first things I would look at, amongst other things...you still don't address the end result...you address the components that lead up to them.Of course, your new perspective on this whole topic really is funny (for anyone that's slogged through this whole thread). You originally brought up rod angle as it relates to side loading, NOT piston speed. Sure is convenient how you're trying to make it look like you were referring to piston speed (and inertial load) calculations all along. Hahahahaha. Since you'll never admit how very wrong you have been throughout this thread, I'll refer the other readers of this thread to your two posts here:
http://www.thesupraforums.com/showpost.php?p=10176&postcount=28
http://www.thesupraforums.com/showpost.php?p=10038&postcount=1

More pointless bantering, as initiated by 1BADSUPRA:
Partially correct. Since you absolutely know for a fact that inertial loads are higher in a stroker, that is your primary concern. ]

Adding 2psi of boost makes more cylinder pressure....doesn't make it a concern. EVERY engine has a stroke....why aren't you PRIMARILY concerned with the engines inertial loads when it is stock??? Single most retarded point you have made yet!



Wrong. At max RPM in a built&stroked 2jz (vs. a non stroked equivalently built 2jz) greater inertial loads will ALWAYS be a problem...and the primary one at that.]


This is where YOU COULDN'T Be More WRONG. The Inertial loads on a 2jz are NEVER a problem. The piston Speed on a stroked 2jz never comes close to being an issue. And don't give me this accidental over rev crap. Anyone who knows anything about the 2jz knows that the cylinder head and valvetrain quickly become the issue at 10krpm. So your limiter is set to prevent the shims from being tossed and destroying the cylinder head, and possibly the rest of the engine. NOT to PREVENT EXCESSIVE PISTON SPEED.


Quit trying to take this out of context. We're talking about a built&stroked 2jz at it's rpm limit here. Sure, you can't calculate the precise increase in piston speed without all supporting data, BUT you do know 100% for sure the stroked 2jz will have a significantly higher piston speed than the non-stroked 2jz at a given rate of rpm ]

Thank you for FINALLY seeing the LIGHT. Based upon this statement alone, you can't make it your primary concern.



Of course, your new perspective on this whole topic really is funny (for anyone that's slogged through this whole thread). You originally brought up rod angle as it relates to side loading, NOT piston speed.]

I brought it up as an one of many issues....the VERY first thing I mentioned is piston speed...which you quickly disregarded, doesn't matter that you went back and edited it out of your post...and then I ALSO pointed out the fact that side loading on the piston is also a concern...amongst other things, and it still is.

Guys, I don't want to sound rude with you all, I barely know you.......

But this seems to have turned into more like physics class to me. Rather than a Supra power thread. Still I like the knowledge and stuff that comes out. For me you are all at par with rocket scientists. Anyway.

Would someone here answer one simple question... How come there are fellas that don't know shit about anything you said in this thread and they barely know how to properly torque a head, but run 9's at the strip?

Refer to both individual statements regarding my comments please I only quoted Jason's post but are replying to both.

Adding 2psi of boost makes more cylinder pressure....doesn't make it a concern. EVERY engine has a stroke....why aren't you PRIMARILY concerned with the engines inertial loads when it is stock??? Single most retarded point you have made yet!

Absolutely true. pwpnanas it isn't always about the inertial load particularly if we stay with the 2JZ subject. It very well could be on some engines but not in this application. Most of the time it is actually the valvetrain that is they weakest link when you start modifying a production engine. Also, saying inertial load without specifying the affected component is too vague and thereby is not a valid argument. To support your argument you need to be specific. Also it is very easy to determine your rod length options etc because you absolutely know how much stroke and deck height you have so you know how long the rod needs to be to achieve a minimum R to S ratio. Piston speed is easy to calculate and general rules of r to s ratio can be determined which of course covers angularity issues.



This is where YOU COULDN'T Be More WRONG. The Inertial loads on a 2jz are NEVER a problem. The piston Speed on a stroked 2jz never comes close to being an issue. And don't give me this accidental over rev crap. Anyone who knows anything about the 2jz knows that the cylinder head and valvetrain quickly become the issue at 10krpm. So your limiter is set to prevent the shims from being tossed and destroying the cylinder head, and possibly the rest of the engine. NOT to PREVENT EXCESSIVE PISTON SPEED.

Because we are all talking about the 2J in these statements, the increase in piston loads for this engine from stroke aren't that significant although it certainly is higher than stock. No one is denying that. Kicking shims out flowing enough air etc are the limitations on RPM in this particular application.

Thank you for FINALLY seeing the LIGHT. Based upon this statement alone, you can't make it your primary concern.

Well actually we do know the data in this example because we can just measure the parts in the HKS kit. Without both stock and stroker parts in my lap at this moment, I can't confirm it but...You may find the HKS kit has a much longer rod or maybe not much longer but still a high r to s ratio and therefore could be not far off of the 3.0 parts and still very safe. Just because piston speeds are higher doesn't mean they are dangerous. It doesn't mean many other issue have less priority.


I brought it up as an one of many issues....the VERY first thing I mentioned is piston speed...which you quickly disregarded, doesn't matter that you went back and edited it out of your post...and then I ALSO pointed out the fact that side loading on the piston is also a concern...amongst other things, and it still is.

pwpanas, you are correct Jason did get into angularity statements. But he did agree very early about piston speed. You however did not define your inertia comments (at least until very late in the argument) and there are a lot of components under the effects of inertia.

I think you both have a good amount of understanding here. Jason and I beat this argument into the ground many times. Part of it was me trying to understand exactly what the hell he was trying to say to you honestly... And I'm not saying we always agree with each other because we don't. I can say that I do feel he really does understand this subject matter. That does not mean you to do not deserve respect for your opinion and you absolutely have valid point that I did defend in our discussions over lunch.

Unfortunatly what was supposed to be an informative debate did go sideways and as offered many times before (like a gentleman) pwpanas, I agree it is time to agree to disagree. Too many hang ups on the word Primary. But I don't think anyone can disagree with me here in this statement.....

The absolute primary concern in stroking an engine is... will the parts actually fit in the block? AKA clearance issues.

Stealth97: Inka is El Pollo Inka resturant in Gardena. 93 stock twin ATM. Runs 7.19 1/8th mile or about 11.15-11.20 1/4 mile on crappy CA tracks. The trick is the car weighs 3800lbs (scaled weight) with my tool bag, computer bag, air compressor/battery pack, and spare tire w/jack. And the kicker is it looks and sounds stone stock down to the factory exhaust stack, stock wheels, and stock air box. Also the spark plugs are the same ones I used in the Vegas `02 event (me and Jason in the finals and I won it last year too). Haven't had a Supra "expert" find any of my modifications yet. I go through CA test only smog stations as it is including the AEM running it. Anyone who knows me can back those statements up. If I take some basic weight out of it and change the plugs I'm sure it would break 10.99

Guys, I don't want to sound rude with you all, I barely know you.......

But this seems to have turned into more like physics class to me. Rather than a Supra power thread. Still I like the knowledge and stuff that comes out. For me you are all at par with rocket scientists. Anyway.

Would someone here answer one simple question... How come there are fellas that don't know shit about anything you said in this thread and they barely know how to properly torque a head, but run 9's at the strip?


Honestly because its guys like Jason, Larry, Rob Smith, Vinny Ten etc that laid the ground work to figure out proven combinations that everyone uses today. Sorry for anyone I forgot. It doesn't hurt to have an engine and drivetrain that is nearly indestructable and idiot proof.

More pointless bantering, as initiated by 1BADSUPRA:
Adding 2psi of boost makes more cylinder pressure....doesn't make it a concern. EVERY engine has a stroke....why aren't you PRIMARILY concerned with the engines inertial loads when it is stock??? Single most retarded point you have made yet!Why do you keep trying to take this discussion out of context. At cylinder pressure, of course 2psi more boost would be the primary concern. However, at max rpm limit (in a built & stroked 2jz), inertial loads is always your primary concern. Repeatedly attempting to refute this is your dire mistake.
...This is where YOU COULDN'T Be More WRONG. The Inertial loads on a 2jz are NEVER a problem. The piston Speed on a stroked 2jz never comes close to being an issue. And don't give me this accidental over rev crap...Bullshit. Situations like missing a shift or winding it out just a bit too much in a lower gear were why rev limits were created in the first place...to protect against excessive inertial load damage.
...Anyone who knows anything about the 2jz knows that the cylinder head and valvetrain quickly become the issue at 10krpm. So your limiter is set to prevent the shims from being tossed and destroying the cylinder head, and possibly the rest of the engine. NOT to PREVENT EXCESSIVE PISTON SPEED.Cylinder head only under max load...and valvetrain only without double springs. Either way, they're irrelevant when considering built&stroked vs built&non-stroked at max rpm. The only relevant issue in a built&stroked 2jz at max rev limit is PREVENTING EXCESSIVE PISTON SPEED.
...Thank you for FINALLY seeing the LIGHT. Based upon this statement alone, you can't make it your primary concern...Only if you take the discussion out of context, which is what you've been trying to do ever since you began to understand this issue, about halfway through this thread.
...I brought it up as an one of many issues....the VERY first thing I mentioned is piston speed...which you quickly disregarded, doesn't matter that you went back and edited it out of your post...and then I ALSO pointed out the fact that side loading on the piston is also a concern...amongst other things, and it still is.More fairy tales. Here's what was said (again):
You: (http://www.thesupraforums.com/showpost.php?p=9993&postcount=26)You mean piston speed!....your getting there...what else?Me: (http://www.thesupraforums.com/showpost.php?p=9999&postcount=27)
You're correct that when I said "Increase in distance traveled per rev..." ALSO means that the speed of the entire piston-and-rod assembly increases...the speed of the piston, the wrist pin, the piston rings, the connecting rod, etc...since (with a stroker kit) you're increasing the distance traveled in the same amount of time...

...Absolutely true. pwpnanas it isn't always about the inertial load particularly if we stay with the 2JZ subject. It very well could be on some engines but not in this application. Most of the time it is actually the valvetrain that is they weakest link when you start modifying a production engine. Also, saying inertial load without specifying the affected component is too vague and thereby is not a valid argument. To support your argument you need to be specific...Again, who would build a stroker with an oem valvetrain? I've been specific all along: built&stroked 2jz-gte vs. built&non-stroked 2jz-gte at max rpm limit.
...Also it is very easy to determine your rod length options etc because you absolutely know how much stroke and deck height you have so you know how long the rod needs to be to achieve a minimum R to S ratio. Piston speed is easy to calculate and general rules of r to s ratio can be determined which of course covers angularity issues...Not necessarily. The variable depth of the wrist pin within the piston can still affect r:s. In theory, deck height could also be reduced or even extended (given 1BADSUPRA's lack of concern for a budget lol).
...Because we are all talking about the 2J in these statements, the increase in piston loads for this engine from stroke aren't that significant although it certainly is higher than stock. No one is denying that. Kicking shims out flowing enough air etc are the limitations on RPM in this particular application...We're comparing a built&stroked 2jz-gte vs. an equivalently built&non-stroked 2jz-gte. You have to admit that the built head very likely has double valve springs (along with porting, oversize valves, etc., etc.). It's even a very realistic possibility that the built head has shimless buckets too. Also, max rpm during a burnout or a missed shift will not be limited by air flow capabilities of the head. Again, the ONLY thing we're changing is installing a stroker kit; the head stays the same! We're discussing the primary concern that limits the max rpm capability of that newly stroked engine.
...Well actually we do know the data in this example because we can just measure the parts in the HKS kit. Without both stock and stroker parts in my lap at this moment, I can't confirm it but...You may find the HKS kit has a much longer rod or maybe not much longer but still a high r to s ratio and therefore could be not far off of the 3.0 parts and still very safe. Just because piston speeds are higher doesn't mean they are dangerous. It doesn't mean many other issue have less priority...If we're determining the max possible rev limit of our newly-stroked 2jz-gte, d@mn straight higher piston speeds is the primary danger to consider.
...pwpanas, you are correct Jason did get into angularity statements. But he did agree very early about piston speed. You however did not define your inertia comments (at least until very late in the argument) and there are a lot of components under the effects of inertia...Unfortunately, he did NOT agree. What he said is "what else", which means he felt that there was a more important item that limited max rpm capability of a stroker. He was, and still is, wrong.
...I think you both have a good amount of understanding here. Jason and I beat this argument into the ground many times. Part of it was me trying to understand exactly what the hell he was trying to say to you honestly... And I'm not saying we always agree with each other because we don't. I can say that I do feel he really does understand this subject matter. That does not mean you to do not deserve respect for your opinion and you absolutely have valid point that I did defend in our discussions over lunch...I do very much appreciate the objective perspective you've taken in this discussion. Fwiw, I am also 100% confident that the first thing any pro engine builder (yes, including Kenny D and JC) would consider, specifically on the topic of max rpm capability when stroking an engine, is increased inertial loads.
...Too many hang ups on the word Primary. But I don't think anyone can disagree with me here in this statement......The absolute primary concern in stroking an engine is... will the parts actually fit in the block? AKA clearance issues...Dave, please don't tell me I have to keep you on topic too. :rolleyes: Please re-read 1BADSUPRA's post that started all of this (http://www.thesupraforums.com/newreply.php?do=newreply&p=9985) AND the title of this thread "Rpm capability and stroked motors!". This topic was never about "absolute primary concern in stroking an engine" (despite many, many, many attempts by 1BADSUPRA to twist it in that direction).
...Unfortunatly what was supposed to be an informative debate did go sideways and as offered many times before (like a gentleman) pwpanas, I agree it is time to agree to disagree...Sure, I'm game if 1BADSUPRA is. In fact, I'll go one further and politely bow out of this discussion at this point. Thanks again for your objectivity Dave. Fwiw, I've unsubscribed from this thread and will not recieve further updates. If anyone would like to contact me via PM or email (pwpanas@comcast.net) to discuss further, I'd be more than happy to do so.

SO....a simple question.... We have ALL agreed we are talking about a 2jz....so given that, are you still saying that the rev limiter is determined by the stroke of the engine?

Since you have already stated dozens of times that it is. Maybe you can explain why Toyota keeps the revs under 7k with the stock components, when they are clearly good to rpms well beyond that?

I just got off the phone from one of the engineers at wiseco. I asked him at what piston speed he would consider dangerous on a 3.46 stroke (stock), and a 3.7 stroke (3.4 stroker kit...actually it's 3.35). His exact words were..."You will never have a problem". I followed that up with the request for some exact numberts. Here Is what we came up with.

stock stroke @ 10k is 5600fpm he said no problem to 7kfpm (Honda guys do this all the time...n/a) Keep in mind reversive loads are far less on a turbo motor becuase the piston remains loaded throughout the engine cycle, unlike a n/a motor where ther is no pressure at the top of the piston on overlap!

Stroker kit (3.70) @ 10k is 6000fpm, he said again...no proble to 7k, then followed it up with "we have NEVER seen anyone pull the wrist pin out of the piston boss" You could probably do 14k, on either, and the piston will more than likely remain in tact.

So... I guess since the "Primary factor in determining your rev limit is Inertial loads". We all need to go out and set our rev limiters to 14k or so! Never mind the fact that with the best components available in the 2j head, you will toss your shims and suck the valves through the pistons at around 10.5 or so... Who cares...."your limiter is determined by the inertial loads in the bottom end".

Here is another little tid bit I stumbled across
http://www.fordmuscle.com/archives/2003/09/stroker/index2.shtml

Unbelievably, one of the VERY first things they talk about in stroking an engine is rod angle....then...what do you know..they actually say your PRIMARY concern on stroked engine is clearances.

So.... to finalize this unbelievably drown out discussion... Your PRIMARY Concern as it pertains to the 2JZ on a stroker (or stock) in setting your rev limiter is Valve train and head flow......PERIOD!

BTW...when I asked for more...I wasn't saying...or...thinking of more important issues....just OTHER issues. The PRIMARY concern can never be one thing when addressing multiple engines, every combination has a different primary concern...as I have stated like....3 thousand times...

i don't think i've ever felt so lost reading an entire thread. i'd love to be able to sit down with some of you guys and learn some of this stuff.

you sure about that?......

you sure about that?......
if you are referring to my post..yep i'm sure. as long as they are willing to be patient with me hehe.

It takes many years. Seriously start by reading everything you get your hands on but ALWAYS consider the source. Magazines and internet can have just as much bad info as good. Consistancy in information adds validation.

It takes many years. Seriously start by reading everything you get your hands on but ALWAYS consider the source. Magazines and internet can have just as much bad info as good. Consistancy in information adds validation.
well i don't plan on becoming an engine builder..i would just like to understand things better..so that when i'm able to put a car together i'm not just some driver who enjoys it but doesn't know what i have.

decreasing the mu is the primary goal to generate higer rpm's, stress loads need the coeficient of friction incorperated. if the mu is droped from the average of .03 for a standered 10W30 conventional oil to the .019 of a synthedic oil higher rpm's are going to be achevible because the stress loads will be decreased exponentionaly. look at all the factors because stress are effectedby not only mass and speed but a combination of them and friction

If you want to minimize friction then use a huge bore and little stroke. Piston stroke is the largest contributor to engine friction. I think I remember a SBC Chevy 350 4" bore 3.48" stroke has up to 175hp in frictional loading at 6000rpm.

That is the same with any mechanical system and an obvious statement. Unrelated to this discussion in many ways unless you want to go back to the discussion of piston skirt side loading. ie rod angle. Clearance is your primary concern as it it doesn't fit it won't even crank yet alone run.....

And generally speaking as it has been since the dawn of IC engines... valve train capability is the limiting force in RPM potential. That is why F1 uses air instead of springs for the valves. Springs get too hot and fail over time.