i was just wondering if anybody had seen this done. i have an xs to4e kit. . . its not the big hp number beast that others are and i figured id just make myself a superstreetable fd. high compression + low boost. should keep the intake temps low. . . combustion temps would be higher i assume. anyways, could anyone give me some pros and cons to doing this? would it be worth it? that sort of thing.

paul

 

As always there's a limit to how much compression you can run and at what cost to engine longevity. Only real way is to do it. I'd stick with the FD rotors though :P

 

i was thinking about just giving my car some more low-end grunt. . .

paul

 

Pretty sure the s-5 rotors are the same as the s6 as far as parts and weight... I'm looking at them right now and i don't see a difference.

Oh wait// you said N/A.....

you can do this... this is what the big boy drag guys do. HOWEVER... because the compression is greater to begin with on the N/A rotors, you are not going to be able to run as much boost, safely. Remember, dedicated drag guys are breaking motors all the time and have spares sitting around!!!!

 

Not as much boost obviously but power is supposed to be made up by the higher comprssion, but I'm not sure if it is more or less. They do get the turbo to spool up faster which is definately a plus.

 

I ran 9.4 compression in an s4 turbo motor...the problem was that the turbo wanted to spool TOO much. Driving at 70 on the highway, the gauge sat right on atmospheric all the time. Climbing the slightest hill puts you into boost. Gas mileage sucks because of this. You do gain a little low end torque, but not what you expect. All in all, I'd say stick with your FD rotors. I am running those in my FC now and they perform just about as well on the street, without the un-wanted pre-spool.

 

That means you need a bigger turbo

 

I have thought of this as well. I realize that high compression plus boost is a recipe for problems, but how much would it really limit the boost? For instance, could one still run 10 psi on 93 octane with S5 N/A rotors? If he wanted to run more boost, he could simply run higher octane, correct? When my current motor goes (which I hope will be a very long time i.e. after law school - 3 years), my car will only be driven occasionally; therefore, I will be able to keep 110+ octane fuel in the tank at all times. BTW, didn't Vosko use high compression rotors in his car?