MARK AUS S2K

I went with the largest size turbo housing of 1.01ar on the latest GTX3076r. It should be the fastest spooling turbo for the street and will provide boost until redline.
The smaller 0.83ar or even the 0.67ar will probably die off around 7,500 - 8,000 rpm

c_me_go

So what about a gtx3576 with a 1.01 AR

MARK AUS S2K

Do lots of research mate. I spent hours reading various members builds for both S2000 and Evo guys and the 3576r was to laggy. Many said the Gtx3076r is best for fast acceleration for the street where you will do most racing. In my opinion a gtx3076r running 24psi on e85 with the larger 1.01 is the best option but I'm not half as experienced as any of these other guys here so please read heaps first.

spdracerut

GTX3576R in 0.83 A/R should spool faster and make ~30whp more than the GTX3076R in 1.01 A/R. Personally, I would not use the 1.01 A/R on anything but the 3582 and looking for maximum power. For a wider powerband I would always go with the 0.83 A/R even in the 3582.

MARK AUS S2K

How do you know it will spool faster? I'm a bit worried about my descision now.
The bigger 1.01ar will match the high flowing head, bigger throttle body, etc... ?
I've read that the difference between the two sizes is that the 0.83 chokes around 7500rpm and stops the car from making as much power. The bigger 1.01ar should have less restriction.

spdracerut

There is a fair amount of data out there that shows the 3576 spools up nearly identically to the 3076. This is due to the change in blade speed ratio and the corresponding change in turbine efficiency. The 3576 has a better blade speed ratio increasing turbine efficiency which allows it to spool basically the same as the 3076 despite having greater turbine flow. Of course, the larger turbine reduces back pressure which frees up power. The 3576 does have greater rotational inertia, so in on/off throttle situations, the 3076 will be snappier. A guy on Evom forum did a lot of testing between the two and his synopsis was if you wanted under 475whp, the 3076 might be preferred. For more power, the 3576 would be preferred. The difference in spool between the 0.83 and the 1.01 housing will be around 250rpm. The 1.01 will make more power than the 0.83 boost for boost because it flows more = less wastegate flow = better turbine efficiency, when operating below the maximum shaft speed of the turbo; so more in the meat of the compressor map instead of the right edge at the choke line at the speed limit of the turbo. But I've seen over 700whp on STIs using the old T3 flanged 0.82 A/R housing. On kill mode shooting for max power, the turbine wheel is the choke point, not the turbine housing. At least in comparing the 0.8x vs. 1.0x A/R housings on the GT30-35 turbine wheels.

c_me_go

so sounds like the 3582 with .83 AR is the way to go...

spdracerut

If you're shooting for 700whp, yes

c_me_go

well.. that is where i am up in the air about,, I have 500whp now with a older gt3076... its totally maxed out.. I love the way its spools,, but just like to have more top end ... I have a fully built motor and rear end and running on E85.. so.. not sure where to go from here.. i am getting a new Sheepey mani and figured i would upgrade this old turbo to something better.. soooo.. gtx3576 with .83AR or gtx3582 with .83AR???

MARK AUS S2K

Mate is sounds like you should go for the new 3576r with 0.83ar