I have a s5 tll with a street port stock turbo and fmic, also has throttle body mod and most emissions and vacuum lines removed, and a N/A tranny. Anyways it runs fine and pulls strong when getting on it but right at 7000rpms it has a complete power drop for a fraction of a second then it goes back to pulling how it was for the rest of the gear. It does this in every gear. Any ideas?

 

Are you running the stock ecu? If so, sounds like the factory boost/fuel cut is kicking in.

 

yes i am, I heard you could use a s4/s5 n/a pressure sensor to fix the fuel cut problem?

 

You have to buy a fuel cut defender, or get a chipped ECU.

 

Is your engine built to be able to withstand that many RPMs? The stock engine isn't meant to be revved up much higher than that...

 

Just all new seals and a street port but I don't know why it shouldn't be able to hold up to 8k, and the engine will be going in my drift car so I don't want it having problems in high rpms

 

"building" the engine is not a concern, especially If you're only running 8-9k, that's nothing. What you should be concerned about is having enough fuel to support the higher boost levels you will be running w/ a fcd or chipped ecu .

What are the details on your setup? I'm assuming its mostly stock if you aren't hitting fuel cut until 7k. With an intake it was around 6k and with exhaust it would hit fuel cut below 5k....for me at least.

 

what you need is an accurate boost gauge to start with.

FCD or a non turbo pressure sensor(if that even works) just upset the stock ignition timing curve.

 

You ignition system could be having problems keeping up. I had issues with my old t2 above 6k rpms in 3rd. The spark just wasen't there.

 

Well I guess it was a mix of a bad fuel pump and a bad fuel filter, i got those changed out and it runs way better top end once its running and I ran it up to 8-8.5k and no hesitation or sputter all was good, just the lack of boost its only hitting about .7bar MAX.

But i got starting problems check this post https://www.rx7club.com/2nd-generation-specific-1986-1992-17/im-stumped-will-not-start-972648/

 

.7bar isn't "low" for a stock car....

 

That's what 10.15psi? It just feels weird cause it has a NA tranny on it right now so it spools sorta slow then hits boost and still runs the gear forever, compared to my friends with a turbo tranny which seems to accelerate better but run through the gears faster and not have as much top end speed.

 

Transmission gearing is almost identical. Do you have the 3.9 rear end instead of the 4.1 that came with the turbo?

 

I believe it's the stock s5 drive line and the t2 swap so whatever came with the s5 vert. I didn't know the NA and turbo tranny were the same gearing, it's just not as strong as the turbo tranny then?