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Noise measurement for trackdays
cloudy - 6/5/09 at 11:00 AM

I'd like to book R4 on a trackday, but want to ensure it will pass noise testing

I understand it's tested at 75% max revs rather than max power at SVA. Can anyone describe the testing process? Do you just have to rev the car for the tester? Can I run a reduced rev limit to limit my noise?

James

adithorp - 6/5/09 at 11:09 AM

Do a BAT track day at Anglesey. Not seen a check done there yet, altough the limit is 105db.

adrian

efiniste - 6/5/09 at 11:14 AM

They usually just check your rev counter and then ask you to rev it to whatever is 3/4 of redline. A sticker to indicate a lower redline may work wonders (assuming this is for analogue instruments).

cloudy - 6/5/09 at 11:29 AM

I have an adjustable limit, and adjustable scale I don't want to be deceptive - just want to know the score before I go...

will121 - 6/5/09 at 12:09 PM

normally taken 3/4 of red line at i think 1m from tail pipe at a 45degres angle. depends a bit at which track you are going to as Snetterton is max 105 db wich is loud, but places like donington a lit lower at i think 98db, dont just look at getting through the static test though, as if they think its loud on track they can also do 'drive by' Tests

idl1975 - 6/5/09 at 12:19 PM

quote:
Originally posted by cloudy
I have an adjustable limit, and adjustable scale I don't want to be deceptive - just want to know the score before I go...


Without naming names, practice varies widely between operators, so it's tough to advise. IMO, it also depends primarily on how strict (i.e. concerned) the circuit owner is about noise.

Generally speaking of course, the quieter the better, except for those rare tracks where there really is no-one around to be offended, since even though it's not reasonable, residents being bothered by noise eventually = track closed and turned into more bloody Wimpey homes. So why not try for as quiet as possible?

wheezy - 6/5/09 at 12:28 PM

I have always been asked what engine I have by the scrutineers. The ones at castle combe know what the rev limit is for most engines.
3/4 max revs taken at 1/2 metre from the exaust outlet. They wont touch the car its up to you to push the pedal and hold it.
Dave

pewe - 6/5/09 at 01:30 PM

Wot Wheezy said ^^ SVA showed 94db but 3/4 revs at Goodwood was 97db.
How strict depends not only on the track operator but local Authority policing. At Goodwood due to local NIMBYs the 100db rule is strictly enforced. They have 6 microphones around the circuit linked to a local council official who monitors the readings whilst the meeting takes place. Any contravention and he/she is on the phone to the circuit telling them to sort it out. Marshals are firm but fair and "had a word" with me when on the opening laps I was reaching 98db coming out of the chicane and the in-field mike was picking that up. They were concerned as I warmed up it would reach 100+. Fortunately the exhaust is on the driver's side so the track-side mikes on the passenger side were receiving a muffled output.
Moral is that it's better to be safe than sorry as it could ruin an otherwise enjoyable day. They give you one chance to fix it then you're off.
Cheers, Pewe

cloudy - 6/5/09 at 02:10 PM

Thanks all,

Does anyone know how static noise translates & compares to drive by noise?

My engine is completely open so a lot is noise from the engine and chassis vibrating - I have some quiet cans but the car won't even get to the rev limit they are that restrictive...

James

spdpug98 - 6/5/09 at 02:45 PM

quote:
Originally posted by cloudy
Thanks all,

Does anyone know how static noise translates & compares to drive by noise?

My engine is completely open so a lot is noise from the engine and chassis vibrating - I have some quiet cans but the car won't even get to the rev limit they are that restrictive...

James


When I used to race my Peugeot 205 it would pass it's static test with ease, but once on the circuit the induction roar on throttle bodies would cause me major problems, esp' at Combe where more than once I was called back to scrutineering bay for a further noise test.

Doesn't really answer your question but shows how they can be wildly differant

[Edited on 6/5/09 by spdpug98]

adithorp - 7/5/09 at 12:35 PM

You can just turn up at a track day (that your not booked on) and ask the organiser to sound check your car.

I can't see the point in turning down your max revs to get through. Would you then run all day on reduced power? If not they'll spot/hear it and you'll be off.

Best just to pick a track with a high limit. (Oulton, Anglesey, etc...105db) or pay through the nose for one of the unlimited days that occationally come up.