General Db limit

[Dakkon]

My car needs a new exhaust so im weighing up various makes of SS ones, with a view that I might take it on the track at some point what is a general rule of thumb for Db limits on most circuits?

Thanks

[iguana]

98db is the normal lower static limit.

Goodwood especially & also Castle Coombe seen to be the strictest.

The prob with 911s, esp air cooled, is they have on occasion been known to fail this even bog standard, (normally coz of noisy tappets etc) simply due to engine noise- as the static test = normally about 1/2 a meter from the tail pipe & an 911 engine is also then only 1/2 meter from that db meter- unlike a 'normal' car with an engine at the front & hence many ft away.

Being air cooled the engine also makes a bit more of a racket than somat with a water jacket around it soaking up the noise.

So an SS exhaust may sound ace, (& 3.2 really benefits too, as quite muffled & unremarkable as standard) but it might restrict the tracks you can use, tho a bung on the end type muffler for tight noise track days could get you through.

[Dakkon]

Thanks, I used to run an MR2 Turbo and have been to Coombe a few times so I was aware that it was 98db, just wanted to check if that was generally considered the lowest.

I have asked for a quote from Hayward & Scott for a custom exhaust and see what they say.

Thanks again

[martvr]

Combe is 100dB but usually strictly applied. Goodwood I think is 98 or at least it was a couple of years ago.

[kickstart]

Goodwood do have regular 105dB days. If you think 911's have problems with noise you want to try and reduce noise on a big single seater when the exhaust is only about 2 foot long...