noise limit

sibbat2 · 04-22-08, 06:38 AM

Went to Castle coombe circuit yesterday to have my CAV GT40 noise tested so that I could attend a track day next week. It was 110db! at 4500rpm whereas the limit is 100db. I am a little surprised since my car was 101db at 4000rpm at the SVA test about 6000 miles ago. Does my muffler need repacking?. Your thoughts would be appreciated. Now I am thinking of booking a track day at Silverstone,what is the noise limit there?.

Ron Earp · 04-22-08, 06:53 AM

Thread moved to the proper area - "The Race Track".

Malcolm · 04-22-08, 07:06 AM

If you run high rpm you will empty your silencers quite quickly so repacking is a sensible way forward. I get my E glass from Merlin who are funnily enough based at Castle Coombe!

Tony Hunt · 04-22-08, 11:04 AM

Castle Combe's noise test is notoriously difficult to get through, and is generally regarded to be a non-GT40 circuit.
That said, Desmond scraped under last summer with a pair of extra silencers bolted to his tail pipes and supported on a gantry. Looked a bit like a Whacky Racer!
I accepted their decision with an (expensive) shrug and vowed not to go back.
Tony

Chris Simpson · 04-23-08, 06:54 AM

Attended a track day at Silverstone in March with the Radical. Things have definitely tightened up there noise-wise due to a local complainer who has involved the council. The official limit is 105 db static. There was no static test before taking to the track but they threatened to pull in anyone who exceeded 101 db (I think) on drive-by and static test them and if you failed that you were out. Our radical was OK on a full race silencer, which is definitely more than 105 db at 8,000 rpm static (3/4 of max revs), so it was pretty much business as usual unless you were VERY noisy.

Peter · 05-03-08, 05:39 AM

Bl00dy stupid noise limits at silverstone - nice and noisy on GT weekend 2 wks ago - did they tell the local to go on holiday over that weekend???? wonder how close the day of compulsory silencers on F1 cars is . . . in this country only of course . . . = the day i guess F1 etc will abandon this country.

Chris Simpson · 05-03-08, 02:50 PM

Apparently F1 is exempt from the max DB noise regulations when they are testing at Silverstone - a good thing too.

Howard B · 05-03-08, 05:41 PM

Is that because they (F1) generate more quid for the local economy?
The kind the everyday Joe can't.
The noise abatement seems to be starting across the pond from you blokes as well.

Howard
______________________________________
RCR 40 in the oven
Parnelli Jones 302 as garage mate

Lucas van Altena · 05-04-08, 05:31 AM

If you have nois problem with a few dba's, you solve it by putting on the end of the pipes with a 90 degreas curved tailpipe ending the otherway of the track where the microfoon is placed.
Have a look at from which side the wind is blowing on the track.
We have 85 dba at Zandvoort.

Regards,

Lucas

Mark Charlton · 06-05-09, 12:57 PM

When I bought my car it came "un-muffled" and I subsequently added twin Borla mufflers to it.

Yesterday I headed off to our new local track hoping it would pass noise testing (100 DB at 2/3 redline) measured 50 feet behind the car.

My results? 108 DB! The tester sternly informed me that this was one of the loudest cars he had ever heard and there was NO WAY I was going on the track with it. He added that it was 64 TIMES louder than the new Porsche 911 he had just checked.

A brief conversation with one of the track owners resolved the issue nicely. He said "bring the car around and let me have a listen". Then, after hearing it, a broad smile formed and he said "well, it doesn't sound all THAT loud... can you keep in under 6000 rpm?".

Fantastic new local track: Calabogie Motorsports Park. World-class track design (by Alan Wilson) surrounded by decent run-offs and rolling hills and lots of trees (far enough back).

Anyone headed up this way should check it out — as long as you have a quiet car.

And any suggestions on how I can make my car a LOT quieter are welcomed!

Mark

egoman · 06-05-09, 01:34 PM

We ran the 180 degree headers in my buddys modified dirt track car and they wouldnt even let him test for sound it was so loud. We installed about 8 inches of auger fligghting in the collectors and it got very quiet. He never even ran the mufflers after that and he said the power was not noticibly off either. That car was the most shrill sounding thing I had ever heard before that. We had 4 inch collectors on that car and the flighting was easy to find. 180s are allways louder than regular headers anyway.