what are the advantages of getting a s5 turbo on a s4 motor?
i have a 87 t2. i have been reading around the forums and saw that there was a lot of demand for the s5 turbo.
what kind of power is that turbo capable of producing reliably?
my car has stock injectors, 2.5 inch turbo back exhaust and mircotech lt10s.

kiwon.

 

I was always under the impression that the reason the S5 turbo is slightly better than the S4 (slightly better top end) is because the S5 has a slightly larger rear wheel, however I was told recently that that's not the case, and that the rear wheels are exactly the same.
Which leads me to beleive that maybe the twin-scroll-flap-thing is the limiting factor for a S4 turbo.
I'd suggest pulling the manifold off and removing that flap, as the S4 manifolds appear as though they would flow better than the S5 ones (once the flap is removed).

 

Wasn't the flap there to increase low-end spool?
As for more power, just keed the s4 turbo and send it to BNR.

 

I thought it was there to increase low rev driveability, not performance at all

 

Th S5 turbo has a fully divided manifold, which means the rotary's strong exhaust pulses strike the turbine directly without loosing any pressure into the other turbine scroll. This makes the turbo more responsive. The combination of this and electronic boost control on S5's made the S4's twin-scroll control system unnecessary. The wastegate is also larger, which provides better boost control once you've improved the intake and exhaust. The turbine wheel, compressor wheel and compressor housing are the same as S4, so there's no peak power improvment.

 

Send to turbo to bnr? how much, contacts?