Turbine size housing

[ariman]

I have a question
if I increase the ar of turbine housing(ie, ar 48 to ar 63) and run the same psi of boost(ie 15 psi), i'll have more hps?
Sorry if a stupid question.
Thank for you advice

 

[MasterFrmMO88]

Yes and no. Increasing the A/R of the turbine housing won't do anything to affect the compressor side so if your turbine side has no flow issues at the .48 A/R, then increasing it won't do much to help you. The idea behind increasing the A/R of the turbine side is to allow the turbo to breathe better at higher RPM, thus getting more power, but you'll have increased turbo lag because it takes more exhaust gas to spool the turbo.

 

[ariman]

So, if i run the same RPM and psi? only increased turbo lag and no gain more hps, right?

 

[JusMX141]

By increasing the a/r (or cm2), you're lowering pre-turbine backpressure as well as backpressure within the housing. This lowers EGT's and allows you to run more boost, leaner air/fuel ratios, and more-aggressive timing without detonation. The trade-off is lag.

So YES, it will make more power with proper tuning...but NO you're not going to notice a seat-of-the-pants power increase with no other changes unless your previous housing was horribly-undersized.