hey guys, im curious, what would you have to do to ur motor to run it past 8 psi of boost with out blowing ur engine? im trying to learn as much as i can about rotaries just because im fascinated by them and im looking into getting a t2 in the near future. would u have to upgrade the seals? bigger injectors? heavier duty rotors/housing? is it possible to run safely and reliably past 8-9PSI of boost, say like 14-15psi? tahnks -alex

 

Even though I do not have a turbo car I have read a lot of the posts on here and tried to absorb as much as possible. One of the things that you should be concerned about the higher the boost you go is the danger of running lean. Bigger injectors help to remedy this problem, but you can loose some power down low if you are running too rich. You probably should search around and look for things like fuel management computers and running lean. Running the highest octane you can get is also a good idea to keep detonation away.

 

First off if you get a TII the stock boost is around ~7.5 psi I think. In order to raise the boost you will need to upgrade your exhaust and intake. Along with those you will also need a fuel cut defense chip that prevents fuel cut by tricking the ECU into thinking that the boost is lower then it actually is. Now you wont hit fuel cut, but since the computer doesnt know how much air is actually flowing it will cause you to run lean which means detonation. Do not even run your car if you have an open exhaust and intake or you will blow your engine real fast, within a week at the most if you drive it alot. You will need a fuel pump upgrade and/or injectors to run more boost. Most people start with a walboro 255 lph fuel pump and tune it down a bit with an s-afc ii or whatever they have, then eventually upgrade injectors when they want to run more boost. Also in response to the other person, I belive its lower octane gas that you want. Higher octane is better for non turbo.

 

No, that is not correct. Higher octane has more additives that prevent detonation. The lower octane gasoline is more likely to combust. Higher temps for a turbo car and low octane gasoline can lead to combustion before the actual combustion step of the cycle. This can damage your engine and wear out spark plugs quickly.

 

o yea and s4 turbo II's(1987-1988) have stock boost of 5.5-6i believe..the s5 turbo II's(1989-1991) have 7.5

 

LOL....i remember hitting fuel cut on my first TII

14-15psi is not going to make your turbo happy.

once you get a FCD and a pump 10psi is a good number. odds are you'll get past that with just an exhaust/intake. You might have to port your wastegate too.