db's?

Mike Usiskin · Post by **Mike Usiskin** » Wed Sep 09, 2009 2:20 pm

is anyone going on the C2C with a decibel meter? I'd like to retest mine as it's had some welding done after small cracks appeared. I'd like to see if there's a track in the UK I can get on

M

Ferry Man · Post by **Ferry Man** » Wed Sep 09, 2009 2:23 pm

Mike,

You're welcome to borrow mine.
I can ship it to your home address tomorrow (for next-day delivery).
'You at home on Friday?

hot66 · Post by **hot66** » Wed Sep 09, 2009 2:34 pm

Mike Usiskin wrote:I'd like to see if there's a track in the UK I can get on

M

well if mine with stock box registered 105dB at Goodwood god knows what your's must be

New nosie regs are getting worse

I think Croft is now 95dB

higs356 · Post by **higs356** » Wed Sep 09, 2009 3:27 pm

This is usually a single point measurement ...correct? where one is trying to make the most of the 1/r2 rule for noise attenuation ...sooo...
Are there any tricks to this that work in reducing the dB when visiting a circuit ...

Supertrapp ?
Steel wool in the exhaust pipe exit ?
2 exits at opposite ends ?

Someone mustve been through this

Gary71 · Post by **Gary71** » Wed Sep 09, 2009 3:41 pm

It's normally 2/3 maximum revs, so a revised red line for the day has been known to help. Dipping the clutch also reduces the row ever so slightly.I

Mike Usiskin · Post by **Mike Usiskin** » Wed Sep 09, 2009 4:31 pm

someone ( i won't mention names) suggested putting a switch under the dash which when pushed would give a false readout for the marshal (who's normally looking over your shoulder) he/she suggested that it might be able to cut 1000rpm off so in my case it would say 4200 but be 3200 in reality. thing is though it wouldn't help with the drive by stuff out on track would it?

oldtimer · Post by **oldtimer** » Wed Sep 09, 2009 4:40 pm

Replying to Hig , I managed to get down to '98' db for Goodwood last November , and have since done Castle Combe - a strict 100 db , so it looks like I've got an answer of sorts. I only got the car a year ago so not an expert on its mechanicals....the outline spec is a 1972 ex 911S 2.4 litre MFI engine with SSIs and what looks standard exhaust setup. It produces about 102 db tending to 101.5 as-is , so not too noisy to start....but still needed something to guarantee getting in to most trackdays.

I found a 250mm length of perforated stainless pipe that just fitted inside the taipipe but butted up against exhaust pipe inside tailpipe , so needed a belt and braces to secure. Just about visible in attached pic taken at Goodwood......appears to knock about 2db off so probably down to getting the exact length to attenuate noise

DDK - Die Deutschen Klassiker

db's?

db's?

Re: db's?