I'm new to the whole turbo motor thing, always had n/a's before! I just installed a new S4 motor into my 87 TII, I swapped the turbo out for a S5 with a ported wastegate and as far as I'm aware they run higher boost stock than S4 turbos correct? Now, will I hit boost cut with just this turbo installation? I'm worried that is a possibility. Any help would be greatly appreciated, until I get a FCD I'd like to drive it without worry.

Thanks alot guys.

 

You should be OK if the wastegate was properly ported. As long as the boost stays below 8 psi or so, you should be fine. Install a good aftermarket boost gauge and keep your eye on it.

 

the s5 has a boost control solenoid that bleeds air from the wastegate actuator to raise boost, that's why it runs in the 8psi range.

the s5 wastegate, from my own tests off the vehicle, will be open by 6psi or so.

 

I do have a greddy a/m boost guage that works quite well. Fuel cut tends to happen in the higher gears am I correct?

 

Fuel cut is at 8.6 psi, so unless you overwhelm the wastegate & boost creep, you won't hit it. Higher gears increase load, and will build more boost if your system allows.

But running an S5 turbo without the S5 turbo duty solenoid (can't use it anyway on an S4), will let you hit ~6 psi. The wastegate has the same 5.5psi spring as on the S4 turbo.

Besides a boost controller, only boost creep will take you over this pressure level. But your wastegate is ported, so that shouldn't be a problem.

 

Perfect exactly what I wanted to hear, I will be sure to keep an eye on my boost guage and all shall be well. Thank you all for your help. ^^