How loud is my car? Worried...

[TurboNelly]

Morning all,

I have booked to go on my first trackday next month - the Autocar Porsche day at Bedford Autodrome.:driving:

I'm now having a panic that it will fail the noise tests and i won't be allowed to take part. The car is a 2001 4.5 with sports exhaust but no decat. Not too noisy at idle but really bellows when you jump on the loud pedal.:D

Has anyone measured these with a db-meter? The limits are 87 dBA drive-by and 101 dBA static, but I have no idea what distance / revs these are measured at.

Anyone done a trackday at Bedford with a Cerb with sports zorst?

Thanks in advance....

[S1X OK]

I did a day at Bedford with the HPC in Feb. As you arrive at the venue, two guys come up to the car, one goes to the back with a decibel meter and his chum asks you to rev the car - I think I was asked to take it to 4000. The guy stood at the window and watched the rev counter to make sure you hit the right speed, so no lifting off beforehand.
My Tusc with standard exhausts got through OK, but I should imagine a cerb with sports exhausts my struggle to get past the sentries.
I suggest getting measured before the gig to avoid disappointment.
Good Luck
Pete

[PetrolTed]

Nelly, I'd echo that comment. Get it checked beforehand or you could be disappointed. Generally speaking standard cars pass the noise tests at Bedford but modified cars often fail.

[jeremyc]

BookaTrack will hire you a noise meter for a few days so you could measure it yourself.

Or, if you're close to Bedford you could call in and have them test the car for you prior to the event.

From the Autocar trackday FAQ:

autocar said:

At Bedford Autodrome we have two noise tests. First your car will be subjected to a static test, in which the noise level is measured 50cm away from your exhaust pipe with the engine at 75% of maximum rpm. The reading must not exceed 101 dB(A). Secondly, and more significantly, your car must comply with our drive-by noise limits. The noise emission from your car must not exceed 87 dB(A) measured 20 metres from your car, which shall be accelerating maximally at over 60 mph. All standard volume production cars will pass this test with ease, so, for example, if you have a standard Audi, BMW, Porsche, Subaru or Mitsubishi you will have no problems at all. The drive-by level will probably be less than 80 dB(A). Cars, which tend to fail the test include most bike-engined cars, eg Westfields, Radicals and Caterhams, plus cars fitted with particularly loud “high performance” exhausts, as sometimes fitted to, for example, Caterhams, Lotuses, TVRs and Subarus. If you are at all concerned that your car may not pass, it is advisable to either come to Bedford in advance for a free noise check, in which case e-mail [e-mail] to arrange this, or try to get an independent test done locally to you. You could try www.association-of-noise-consultants.co.uk to find a local noise consultant, but they are likely to charge you for this. It must be stressed that the drive-by limit at Bedford is not something that can be "cheated". The noise monitor records continually and we also have other noise meters around the track, so please do not think you will necessarily be able to continue running if you can pass the initial check.

[zumbruk]

PetrolTed said:

Nelly, I'd echo that comment. Get it checked beforehand or you could be disappointed. Generally speaking standard cars pass the noise tests at Bedford but modified cars often fail.

Which, given that it used to be the MoD research airfield and all kinds of whacko stuff came over at unsocial hours, then TNT Skypak were going to operate it as a cargo terminal, licensed for 6000 aircraft movements a year , you'd think the residents of Thurleigh would have been chuffed to bits to get JP. We even decided not to buy a house in Thurleigh because of TNT. I bl**dy wish I'd bought it, now!

(I can see the old control tower from my back garden, but have never heard JP's operations. We can hear Santa Pod when the wind's in the right direction, which panicked the guy on the 'phone once, but I (and Mrs. Z.) think that's a lovely noise!)

(And I've never been to the Autodrome. Grrrrr.)

[parrot of doom]

Wire wool is a good way to reduce the noise from the exhausts, isn't it?

[TurboNelly]

Thanks for all the comments chaps.

I have emailed Palmersport about arrranging a noise check at Bedford prior to the event. Will let you know how i get on.

[rev-erend]

I have a noise meter - I measured Steve T's Cerb 4.5
(cats & std exhaust)

4500 rpm = 99.6 db
5250 rpm = 102.6 db

All measured at 1/2 metre @ 45 degress to exhaust.

The rpm figure is supposed to be 75% of revs - so 4500 is 6K, and 5250 is 7000..

I'll happily measure yours if you are around my area.

[Terminator]

parrotofdoom said:

Wire wool is a good way to reduce the noise from the exhausts, isn't it?

Isn't wire wool is a bit tough on the inside of the ear?

Zumbruk, are you going to visit the Motors at Canary Wharf next week?





>> Edited by Terminator on Friday 10th June 10:58

[TurboNelly]

Rascal - may well be up for a beer. Not sure how many of us are coming yet. Lotuslad was talking about maybe coming, and there are a couple of other possibles. Few other PHers going as well:
www.pistonheads.com/gassing/topic.asp?t=183653&f=18&h=0

Rev - thanks for the offer, but i may as well get a free check at Bedford with their own noise meters as they are the ones that matter.

[Nuggs]

Have you thought about getting a pair of tailpipe silencers from ACT? IIRC, they hire them out as well as sell them...

[TurboNelly]

How do they work? Would they fit my exhaust? It's a custom Hayward and Scott system.

[Nuggs]

TurboNelly said:

How do they work? Would they fit my exhaust? It's a custom Hayward and Scott system.

Dunno guv... Give Tim @ ACT a call, he'll be able to help you.

[TurboNelly]

Cheers, have dropped him a mail.

[FlipFlopGriff]

Had the Griff tested at Donington. 500 - Taraka upgrade with sleeved pipes in the back box and wadding removed. No other mods.
97 at idle and 110 at 4,000 revs. Static test only.
FFG

[Chuggaboom]

If u go to Castle Combe tommorrow u can get it checked for nought...classic action day and everyone gets tested b4 they go out....u can get tested then simply not buy a ticket.

[tvrolet]

Hihack!

curious how they measure side exhausts. If they go 45 degrees (or whatever it is) 'ahead' of the outlet I'm guessing the meter would also pick up engine noise that would 'corrupt' the figure, and if the go 'behind' the outlet, although the may be at the correct number of degrees to the outlet pipe, I'd guess the actual emisions (and noise) would still point more towards the meter as the outlets just turn the gas after it running down the site of the car.

Plus, are the driveby meters on the left or right side?

What if the driveby level on the non-exhaust side of the car is way under. Will they still try to do a driveby on the exhaust side?

Just curious....

WB