There isn't any machining of the turbine housing/wheel. We just take a standard P trim turbine wheel/housing mated to a t3/t4 chra, make a custom backplate and slap on a To4S housing with a Gt35R wheel. Basically this is nothing more than an updated 60-1.

Bigger turbine a/rs in my experience come into boost sooner. They do however take longer to get to full boost. I like this as it doesn't shock load the drivetrain with a sudden jump in torque from really fast boost rise.

 

Thanks for helping me understand. So the "secret" is more/less utilizing a large A/R T4 housing with a high turbine trim mated to relatively smaller compressor? And is there a limit: I.e. why not go 1.34 or 1.52 turbine A/R?

 

There is a balance to everything. The bigger the a.r. the bigger your exhaust system, and the less restriction you need to help balance things out or it will be too peaky of a turbo system. Bigger a.rs also breather a lot better on the top end and therefore lower egts another nice benefit...

 

Thanks for clearing that up. I was under the impression that it was only a wheel swap.

 

Good info thx

 

Seems like you did a good job putting your car together, have fun.

 

I have a very similar setup (aspec kit). I'm thinking or tuning up to 22psi though. What fuel setup are you running now?

 

Car runs EV14 550cc primaries

http://www.turbosource.com/category-s/1933.htm

and ID2000 secondaries

http://turblown.net/store/index.php?productID=63