napacruzerc5

Need opinions for autocross/street only setup (no-track days). I have a01 MN6 coupe with the F45 shocks, lowered on stock bolts and nothing but a CAI and cat-backs in the power dept. I was running chromed repro Z06 wheels with Kumho MXs 245/45/17 fronts and 295/35/18 rears and not have been able to put the power down. It doesn't seem like I'm getting any heat at all to the rears (picking up less than 5psi after starting at 32). I'm going back to the stock OEM thin spoke wheels with stock sized Kumho MX 245/45/17s and 275/40//18's. This tire and wheel set-up are approximately 25-lbs per corner lighter than the chrome repros (which I'll keep for street bling). I have a set of C6 Z51 sway bars which I'm considering installing. I'm also considering only installing the larger front sway and leaving the stock sway in. At back to back events (Sat/Sun) I could start w/ the front only then install the rear the next day. Opinions please - good, bad, ugly and no I don't want to buy a Z06 (ZR1 maybe but haven't won the lotto yet).
Thanks

fej

I am guessing you were at Alameda? With the temperatures out there you are not likely to see more than a couple of degrees max increase in your tires in a 45 second course. Generally most people feel that a bigger (but not giant) front bar and stock rear (and some run no rear) bar helps with turn in a bit.

25lbs per corner drop will help a ton for sure, but street tires are limited in a tight but fast course (60 second course = at least 2 seconds on R compounds, usually more).

I do not know how experienced you are, but IMO increase the seat time before you start making whole sale changes to the car setup. If you learn to get the car around consistently on street tires, you will see increased benefit from moving to R compounds vs jumping in with suspension changes and R compounds early in your AutoX adventures.

My personal opinion is that you need to make a plan on whether you want to go out and be competitive, or if you just want to go push the car to its/your limits and not worry about how fast you are against others in a given class. if you want to be competitive decide what you are willing to do to the car, check the rules and map out your plan of attack.

G'luck
Fej

napacruzerc5

fej

I'm a long time autocrosser just wanting to have more fun with my street C5. Been doing this since the late '70s including numerous trips to the Solo II Nationals. So I've had the seat time in all kinds of cars from open wheel Formula types, too many Fiats, a Fiero GT and a '68 B-Prepared Corvette roadster (runnerup '86 Solo II BP Nationals - I still know what pylon cost me the win). So just wanted some opinions to my proposed changes since the car set-up part of the sport is not a strength. And no I wasn't at Alameda last weekend although I really wanted to be there. See you maybe 4/18-19 at Solano? Look me up #784 Torch Red C5.

Rhys

TedDBere

OK, here's my opinion.

Take the intake off and return it to stock.

The SCCA has a proposal out for 2010 which would create a "tweener class" between SS and AS. They would leave the Z06 in SS but move the non-Z06 C5s to the new tweener class where they will now be competitive.

Try the bigger bar on the front and leave the stock bar on the back. Get good shocks depending on your budget.

The only non-Z06 C5 to win nationals ran on 275/17s and 285/18s but you won't want this combo for the street because it'll mess up your computer unless you turn it off. You'll also have to reset your rake and alignment because the rear diameters are so small. Same tread width as the 295s btw, believe it or not.

Good luck.

fej

Thanks for the background Bar information still applies, and some of that really depends on your driving style. Some people love stock spring rates and a ton of sway bar, some people go the exact opposite.

I would probably look at shocks for sure (I think that is your weak link), try the Z51 front bar and the lighter tire/wheel set up. Sell the repros and pick up a set of real z06 rims and throw some rubber on those if you find you want more tire at some point and are not worried about class.

G'luck
Fej

napacruzerc5

I'm not doing SCCA events. Been there, done that. Also p'o'd at SCCA for the demise of BP. Just local WSCC all Corvette events. Just for fun.

I'll try the front C6 Z51 bar first. Thanks for the opinions.