cscothon1015

Im planning on swapping out my 88 T2 rotors with NA rotors from a 91. I've heard the compression rate is higher. Has anyone done this before, and what was your experience with it?

RotaryRocket88

iTrader: (7)

S5 NA rotors are 9.7:1 compression, while S4 TII rotors are 8.5:1. Higher compression rotors will have the most significant effect on off-boost power, but it also requires much more precise engine tuning. A programmable computer will be required to retard timing under boost and increase fuel delivery to prevent blowing the engine.

198713bt

iTrader: (2)

How drastic would the timing need to be adjusted if running S5 TII rotors in an S4 TII??

MrGoodnight

iTrader: (1)

I also have a question/inquiry:

If you use s5 NA rotors in a t2 since you have to retard the timing a significant a mount will the added com

MrGoodnight

iTrader: (1)

*compression offset set increased low end and spool?
Will it help increase mpg?
Would 9.4 rotors be better suited for higher comp turbo?



-Kyle

Aaron Cake

iTrader: (1)

I wouldn't run more than 10 degrees total advance after about 10 PSI on the 9.7:1 rotors. The stock TII ECU runs in the high 20s under the same circumstances.

There would be a definite improvement in spool, and a mileage improvement as well. But only in an ECU tuned properly.

On a stock TII there shouldn't be an issue spooling the turbo anyway.

Honestly, my opinion on building a 9.7:1 turbo 2nd gen is to not do it. You're not going to gain much over the 9.4:1 rotors, which can be very reliable in a turbo application if tuned correctly.

198713bt

iTrader: (2)

Aaron, would there be an issue running 9.0 rotors instead of 8.5?