does any one know how to tell what spring you have in a greaddy wastegate? Im assuming they are color coded some how?

Red is stiff (22psi min), Blue is regular (15psi min), Yellow is weak (10psi min)

Chris

thanks man thats a huge help. I think I have to stiff of a spring...

that is some good information...never knew the greddy springs were color coded...thats niftyyyyyyy

I have the yellow spring in my car, I took the blue one out to control the boost a little lower, but now it seems like I cannot boost over 1.1 - 1.2 bar on the yellow, are there limitations to the upside boost potential on the smaller springs?

Never use a smaller spring than the blue one. There's no point in a supra to ever boosting below 15psi. People debate me on this all the time, but you can get over 100,000 miles on your motor if you only boost to 15psi. If you're spring is too weak, the wastegate only relies on vacuum pressure in the diaphram to keep it closed until the proper point. That's why you want the highest boost spring that you are willing to run all the time.

Chris.

Thanks Chris, I will change it out immediately. What PSI on pump gas do you think is safe to run on a T78, stock motor, on a full fuel system with 880cc injectors?

32psi w/race fuel.

What PSI on pump 91 octane? Thanks for the response in advance.

17-18psi. You can always get an AEM and monitor your knock values. :)

I have an AEM, just need to learn how to use it :snork_lac

I have an AEM, just need to learn how to use it :snork_lac

Just put some good octane fuel in, set your timing to be conservative and datalog your knock#1 raw and knock#2 raw values. Then set up the knock noise table to correspond to these values. Then put in the shitty gas turn the boost to 17psi and again datalog those values. If you see the knock spiking past these prior limits than you're running too much boost or too much timing for the gas. You can improve power quite a bit by simply increasing timing, but be careful with this.

Chris.