Originally Posted by dsm's can fly
the compressor map i was looking at on the Garrett website looks like about 70lb min. That being said there are a few people who have made more than 700 hp. I know Tim Zimmer being one of them. As for the boost i will probably not take it past 30 psi. that is a guess though at this point because i will raise it up until the tune becomes unsafe. I am looking to make a little over 700 hp, so far i think i am on track, time will tell though.
On the GT4088R, the peak efficiency of the turbo is around 36-37psi on a 0.96 A/R housing with a 2.3L-2.4L setup. Past that you will start to see lower power gains, higher rpms from the turbo, lower efficiency, and more hot air. It also it substantially more reliable if you stay below 40psi. With that said, I ran mine between 30psi and 49psi for 3 years before it finally snapped the shaft at the compressor wheel.
This turbo was an absolute beast between 30-40psi. Get some race gas in it and check out how it does around the 36-37psi manifold absolute pressure.
I still think that this turbo can make 825AWHP with the right turbine housing and overall engine combination. The power you are making on your high compression E85 2.4L puts mine to shame as it was just a 2.3L 7-bolt with Eagle/Ross and a 0.96 A/R divided T4 housing with 93-octane and VP Q16 fuel depending on boost levels. I also ran really safe timing maps and know that more power was obtainable from it. You are making similar power levels to my old setup with 10psi less boost. All about efficiency!
Turn it up! It will be lots of fun!