T2 S4 stock Turbo & manifold mod questions
 

Ive heard of people removing the flapper from the manifold however I cannot find a write up about it. Im also looking for any other ideas as to what i can do to the stock set up(other than porting the waisegate hole) that would be benificial before i prepair to bold the set up on the engine. Thanks for any help :)

hey
 

i plan on using a 89-91 turbo housing. It has a much more efficent wastegate. you basically use the internals of your turbo. So you can buy a bad 89-91 turbo and just use your internals. I think you also need the coolant and oil lines from the 89-91 turbo. The s5 turbo also is made of better material and is less prone to cracking. You can then mod all you want and won't have to worry about fuel cut as much. I've been planning on doing this for a couple of weeks. Just getting all the parts toghether. I'm curious to hear from other people about this mod.

If you plan on using the 89-91 turbine housing, you will also need the turbo manifold.
S5 still gets cracks.

You still have to worry about fuel cut.


Im curious who's all gonna tell you that your statement is not correct.

To answer your question, theres a debate about the flapper. Do a search, i do recall a properly working flapper door, will make boost a few hundred rpm's sooner.
For the wastegate, also there's a thread, about using a honda or a Ford F150 exhaust valve welded on the stock wastegate after it was milled out.

Also search for BNR turbos,they build very nice modded stock turbos

Good luck

KEY words---- LESS prone to cracking---- Worry about fuel cut as much.
Just giving idea's to the man and nothing is incorrect!

Can you elaborate?

Maybe I'm not understanding you. How come just because the S5 turbo is made with better materials (if it even is) and "LESS"prone to cracking, that you would be able to 'mod' all you want and not worry about fuel cut 'as much' ?

A local guy around here who has a wonderful rx7 recommended this mod for me. I just want depandablity with a little more power. I'm still trying to research this mod. LOt's of planning can go a long way. To my understanding the s5 turbo had a much better wastegate. It will help getting boost creep under control. He also recomending a boost controler and fuel cut defender. Heck if you have your turbo out and your gonna port the wastegate just go a little further and have a better setup. Am I missing something here? I am new to turbo setups and I'm trying to learn as much as I can. Thought it might give idea's to this guy with moding his turbo.

You are correct about the S5 wastegate being better. It uses a "double flapper" wastegate vs. the single on S4.