anyone know how many ponies the s15 oem turbo (i think its the gt28r) is good for

 

It's somewheres around 300-350 depending on the tune. I think it looses efficency at like 16psi.

 

Search for the compressor maps

Then do some math

 

try 22psi

and yes if you upgrade your injectors and do some other little things you can make over 300 on them.

 

Not calling you wrong Cole, but I thought it was 18psi?

 

no.

T25r - 15 psi
GT28r - 22psi

 

don't want to talk about him but tom had his AFC hacked at 18psi and made 300whp on a s15 sr20 and stock injectors. and still had 4 psi till it was maxed out.

 

Theres people that run 22psi but just because you can do it doesnt mean its a good idea. When a turbo starts breaking apart = metal shards and shit in your engine = kaboom! 16psi is the safest but 18psi is doable with the right injectors, fuel pump, fpr and tune. Personally I would upgrade the turbo if I wanted to run anything over 18. If you really wanna make more power, upgrade the cams, cometic headgasket, arp headstuds, new timing chain/guides.

 

This should be what you are looking for

 

S15 and GTI-R T28's are good for 21-22 Psi