I was wondering if you could use the S5 rotors in the S4 housing. I have the rotors from a 1989 already, and would like to put them in my 1988 housings. I would have used the housing for the S5, but the front side housing, and the intermediate housings had blow outs at the water jackets.

Yes

Lighter and higher compression, too

Thanks for the replies. I was hoping that was the case, so i can get more ponies https://www.nopistons.com/forums/pub...IR#>/smile.png

You also need the counterweights to match the rotors.

Yep.



Not as simple as just swapping the rotors.

Not to meantion the flywheel as well. But alas, you should get 10 hp or so.

I would like to do this same thing. I have one good rotor and the counterweights, however the car was an auto. Will the s4 flywheel work, or will I have to find an s5? Also are the rear counterweights different between manual and auto?

ok here it goes



rotors-



rotors weight the same in each series. S4 NA weight the same as a S4 TII thus the counter weights are the same. Compression and weights are different between series and TII and NA rotors are different compressions too within the same series.



Flywheels-



Manuals have the counter weight built into the flywheel. Since there is different weight of rotors between series the flywheels are different between the series.



After market flywheels-



If you want an after market flywheel you need the counter weight from an AT from your SERIES.



Transmissions-



these must match your clutch/flywheel