Hey guys, my bud that has an '87 sport is going to be getting a rebuilt soon, his lost compression in the front rotor, so hes planning on trading his core from Mitchs (?) Auto in Detroit. I'm wondering if he can have it built with S5 rotors, I thought I read on a thread that this would bump his power up and still run cool. Possible?

 

You need the whole rotating assembly.

 

What does this include?

 

Yes, the higher-compression S5 rotors will make a little more power, but the engine will run a bit hotter due to the increased compression. You will need a S5 flywheel and counterweights to go along with those rotors. Since the entire rotating assembly needs to be balanced, you may as well also use the eccentric shaft off the S4 donor engine.

 

From what I understand all you will need is the rotors and the front and rear counter weights. But make sure you compensate for more fuel because of the higher compression.

 

Hmm, that may be, but the S4 flywheel = 24lbs, and the S5 flywheel = 22lbs, so that sounds different to me.

Good point on the fuel.

 

You know, now that I think about it, the extra fuel to cool down the air charge may not be the best thing. Higher octane fuel would probably work just as well to combat detonation, and it would probably yield better power than running a richer AFR. The compression isn't really all that different, so I'm not sure how much it really matters though.

 

the flywheel has to match the tranny. no worries about the interacting with the rotars. otherwise lightweight counterweights wouldnt be usable on our cars.

if ur using S5 rotars get some counterweights to match. thats what counterweights do, counter the spin of the rotars so they need to be the same weight.

btw i use an 88t2 tranny/flywheel/clutch on my S5 n/a. just worry about the counterweights.