Meta

I'm considering an upcoming HPDE event at Lime Rock in September and I'm concerned that my setup won't pass noise restrictions that limit cars to 89db or less. Knowing that there are lots of variables, atmosphere, microphone placement, etc, that can make a significant difference, I know there are no sure bets other than a stock setup. Even that apparently can create problems for some Porsches and Ferraris apparently! Anyhow, on an '02 C5 I'm running AR 1 3/4" long tubes with cats, with a B&B PRT exhaust. Intake is stock. What do you guys think my chances are of being flagged? You folks that are track regulars I'm sure have seen a lot of cars getting nicked for noise over the years and have some sense of what will work, what might work and what won't have a chance. Don't want to get there and get tossed after only a few laps. Thanks in advance!

lefrog

Most people get caught in the front straight. Just don't go WOT on the straight if you don't want to be blacked flagged. It depends on the club, but Lime Rock is pretty strict on the sound limit. I had a straight 3" exhaust with spintech muffler on the C4 and never had issues. My C5Z has stock exhaust to no issues either.
If you car is obnoxiously loud already in the paddock, they will likely pay extra attention to you on the track...

JSTAN

If your mufflers tips are 3.5" in diameter, you can buy these I have for sale.

http://forums.corvetteforum.com/auto...-mufflers.html

I ran these on my supercharged 02 Z06 with Kooks LT headers, off-road X-pipe (no cats) and Ti Z06 mufflers and never had a problem at Limerock.

Just redirected the exhaust away from where they take decible readings.

Meta

I would buy your turn downs in a second, except that I don't think they'll fit my quad oval exhaust by B&B. That might limit by options considerably. I don't think the tips are removable either. Do you recall how many decibels you were running or only that you passed?

troyguitar

89dB is really quiet depending on how it's measured. I'd guess you have about zero chance of passing.

Meta

It's 89db from I believe 50 feet away. Distance changes things considerably.

JSTAN

Maybe you could pound them into an oval shape..LOL.

No idea what the reading was....I only passed and never got black flagged.

RallyeChris

I have never had a problem at LRP in my 02 Z06 with stock manifolds/cats/x-pipe and Borla Stinger exhaust. I think the Borla Stingers are pretty loud, but not 1 issue there with 3 different clubs. It seems the way he small block Chevy makes noise, it has volume but not db? I dunno, but we had some difficulty getting BMW inline-6 engines to pass when they didn't seem very loud. There is a sophisticated technical discussion regarding frequencies, etc., but all I know is the Vette seems loud to me, but no problems at lrp.

TKOGTO

Conditions influence levels as you know. First, hope for clear day with winds that travel toward the hill next to No Name. Low clouds with little wind tends to be louder. Plan B, as suggested above is to lift as you approach the tower. This is where the db levels are usually measured. I was flagged late last year with a stock setup sans an intake. I get the sense though that the measurements may be limited to the morning. I did the lift thing for about half of my 3rd session of the day (flag occurred in session 2). From then on I was back to WOT and didn't get another.