Noise checks

[Willsie]

I have recently purchased a Caterham that was one of the Caterham Vauxhall powered race cars in a former life. It is in a high state of tune and estimated at around 250bhp. It is also extremely noisy!

I plan to take it to its first track day in the next month or so but dread the idea of arriving and failing a noise test and being consigned to watching everyone else on the track from the pit wall.

Does anyone know where I can get a noise check done before arriving at a track day?

I also know there are different types of test - is there a place where I can have them all done at the same time?

Perhaps someone has a similar car and can take a look at the attached picture to see if your car has the same exhaust system and passed or failed tests at different circuits?

The car is based on the M25, between M4 and M1.

Any assistance or advice gratefully received.

Willsie

[Stephen Green]

Hi Willsie and welcome to Ten-Tenths.

If your Caterham as a race car then surely it would have passed noise tests back then? You may find however that noise levels vary from one circuit to another and so when you have made your chioce of where to run, check with the circuit office to see whether they have noise limitations in place. I would explain to them the car you have as they should be familiar with the level of noise expected?

[Willsie]

Stephen,

Thanks for the response. I think a lot of the development work was done after it finished its racing life so it was probably not in this guise when used in the race series. The exhaust seems to 'crack' and 'pop' at times and the induction noise is quite loud as well. I realise different circuits have different rules but was hoping to take it somewhere, have it tested and then I would know which circuits I could run on and which to avoid.

Then in the worst case I could replace the exhaust with something quieter (with a comparable reduction in grin factor as well!).

Thanks,

Willsie

[JimW]

Welcome to Ten-Tenths. I suspect that you will have some difficulties in getting a firm answer. Noise testing is only an exact science (?) if one spends shedloads of money on a "standard" environment. So testing at practical venues has lots of variability. So getting an answer beforehand will be tricky.

I would suggest that you might make contact with one of the "Environmental" scrutineers (horrid PC euphemism for Noise scrutineer) who you will find listed in the MSA Blue book. I'm sure they will give good advice.

Regards

Jim

[Hobson]

Hi Wilsie, welcome to the forum.

I think everything already said here is correct, the bats course of action is do as JimW says. Also,take a more standard exhaust along to the track with you, just in case.

After all, your grin may get smaller because of the sound, but going onto the track will sort that.

[mhayter]

I think it's possible to get noise meters at Maplins for about £35. I'm sure they're not as accurate as those used at the tracks, but it should give you a reasonable idea. There is a huge variety of noise limits at the circuits - just check out some of the events on the Bookatrack site. They range from 98db static to 105 db driveby to unrestricted.

Judging by the spec of your car, I suspect it would certainly fail at quite a few circuits (particularly if they were running one of their "quiet" days.

RMA seem to run days on circuits with relatively high noise limits. If you're a member of the Lotus 7 club, they're also doing a substantial membership discount at the moment.

[kickstart]

Why not take your car along to a track day (that you have not paid to attend) that is nearby and ask them very nicely to noise test the car, on the basis that you plan to attend one in the future.
The "noisy" track days are up to 105dB and my guess is that you may be somewhere around this figure if not higher, MSA limits for racing is 108dB, which may not sound a lot more but as I recall actual noise doubles every 6 - 8 dB. My race car does not sound that loud to me, a Formula Renault, but is 107dB.
If you got a race licence then you could do the test days at Silverstone and Donington, which have no noise restrictions and you could make as much noise as you wished.

[Paul V]

One thing you need to do before getting it tested is to check the status of the packing in the silencer.
A simple check is to tap the can with a metal rod along its length. There should be a 'ting' where it is empty (usually front) and a 'thud' where it is packed.
If you need to repack (I hope you have removable end pieces)
, get good quality material, and don't overfill it. It should feel like pressing on a pile of towels.
Pack it too hard and the gas won't expand into it to begin with, which makes it nearly as noisy as a straight through pipe.

I Hope this helps.