matty

I will be running my first road coarse event soon...i cant wait.
Anyways, Lime rock requires that the vehicles involved must be no louder then 89Db. My relevant mods are a dp, resonated mp, and a rb dual tip cb. My motor and turboes are stock. Am i safe?

buttlips

I would bet that you'll be fine.

Silkworm

Omy car I have to run a supertrapp after the exhaust or else I'm running around 96db. But with a turbo, a resonator on the MP, and duals out back, you'll probably be ok

matty

what's a supertrapp?

specRX7_22

89 decibals? wow, thats really low. summit point's limit is in the 100's. my dads racecar is running a straight pipe this year and it barely makes it.

Silkworm

A Supertrapp is a type of muffler, it uses plates added on to the end of it to disperse the exhaust sound... Not the best thing for a rotary, but short of redesigning the exhaust to work with the draconian 90db limit at Laguna, it was easy enough to use.

PaulC

xplikt

****, I can't be anywhere close to being legal then. I had no complaints from Spokane Raceway Park. There was a guy who races all the time in events there and all over the NorthWest and his car was only a little bit quieter than mine.

He was using a Supertrapp though, so maybe he adds plates when he needs to. When the damn thing passes, you can hear it whistle for half a mile down the front straight. That is more annoying than any rotary can be.

matty

so back to original question..noone has tested the decibel level of a bolt on only FD?

rynberg

First of all, there are other factors necessary to answer your question.

*At what distance is the 89 dB specified? 50 feet is a common distance.

*Does their specification state A-weighted or non-weighted decibels (dBA or dB--sometimes dBC). Usually this is A-weighted.

If you are running a resonated mid-pipe and the RB exhaust, you will probably be OK. The problem is no one can really give you an answer since the car would have to be measured at the specified distance AT WOT in motion. Measuring a high rpm blast while sitting still in neutral will not give an accurate reading....

specRX7_22

if you plan to run the same track many times you can put a turn pipe on the end of the exhaust that faces it away from sound station. or the same thing, except down. thats a common solution at SP. they dont care how you pass sound, as long as you pass it.