I recently blew my stock s4 turbo, and I had a rebuilt s5 one to replace it with. My friend and I built a custom manifold and full 3 inch exhaust while we were at it. Everything seemed to be working fine when we started her up, but there is a pretty descent sized exhaust leak between the turbo manifold and the engine. When I took the car out for a test run, it boosted up fine to about 4-5 psi (ported s5 wg). Then the trouble started. I tried to turn my boost controller up, but it will not boost any higher than 7 psi. And whats worse is that it builds boost slowly and in 1st and 2nd it will build to 5-6 psi only then drop to 4. My question is what could be causing this. Is it most likely the exhaust leak or could there be something else wrong?

 

it's the leak...

why did you build a custom manifold for the stock turbo??

 

Because it was fun.....I dont know, it is a pretty much for a to4 but we are using a falange for the s5 on it until I get the microtech and to4. But it seriously is only the leak. It seems like a pretty funky problem for just an exhaust leak.

 

Anyone else know why it might be doing this. I will fix the exhaust leak but I wanna know what other things could be causing it.

 

thats whats causing it the leak is letting the exhuast gases exscape before the can spoll the turbo...

 

Alright, thanks. Ill take that damn thing off again and try to make the falange flatter and maybe buy a new gasket and double them up.

 

I wouldn't double-up on the gasket if I were you. Check to make sure your flange stayed perfectly flat. That would be my guess as to the cause.

 

Its the leak for sure.

My buddy and I had the same problem on his Miata at first. Tightened down all the bolts and put a new gasket on and it was all ok.