too noisy for track

Guest · Feb 22, 2006

At Bedford recently I was measured at 101.4 db.

I was amazed as I'm running a standard exhaust system on my '91 C2.

All I've done is change to a K&N filter and drill a few holes in the airbox. Would this make a significant difference to the overall noise?

It means I'm severely restricted to which track events I can attend.

Is there any cheap and safe way of reducing the noise to below the magic 100db?

Any tips gratefully received

cheers

Kristian

Elliot Davies · Feb 22, 2006

Find / Swap for another standard airbox cover, on throttle load as you will know the airbox makes a louder sucking noise because of the holes
they are one of the noisiest P.cars anyway.
The K&N wont be making anymore noise than a standard filter

Gordon Attar · Feb 22, 2006

Is'nt Bedford done on driveby? as well as standing 2 foot away!?
The drilled air holes arent helping but I would suspect that putting a normal cover on will get you down the half decibal for Bedford!
I suspect that you may have had a cat bypass or muffler bypass installed before you purchased as a std 964 is meant to be okay at Bedford (see PCGB trackday advice).
What did they say at Bedford

graham harvey · Feb 22, 2006

I was at Snetterton on the 11th for my first track day where it was stated as a 105db day. There was no testing done and my car with a cat bypass, cup rear silencer and drilled airbox was one of the quietest of the day. Do some tracks not bother actually testing or should i not risk it at other places i.e Bedford ?

burrow01 · Feb 22, 2006

Bedford are very stringent - I was "on the edge" with a 3.2 with a sports silencer

They were OK about it, and said that the drive by test was what they went by in these situations - they gave me a red windscreen sticker, so that the person operating the noise meter on the track would know that I was on the limit ( well sound wise anyway) and would pay special attention to me

In the end I had no problems

Pete

Guest · Feb 23, 2006

Ok, so a standard airbox is a must.
I'm getting my fried discs and pads changed by a specialist in a couple of weeks so I'll ask him to check if there's a cat bypass or sports system under there.

cheers

Yoda · Feb 23, 2006

I would agree with Gordon, my car is std apart from a K&N and drilled airbox and I have never had any trouble at Bedford (or anywhere else for that matter). Will be interested to hear what your spanner says about the exhaust.

For what its worth, I have done static noise tests with complete and drilled airbox and it made zero difference. More likely to have impact on drive by but lifting at the testing areas usually works wonders.

burrow01 · Aug 14, 2006

Hi,

Is the 101 Db with the drilled airbox?

Cheers

Pete

Guest · Aug 14, 2006

Hi ,

Good point, it was with the drilled airbox but the previous reading from Bedford was 101.2 with the standard airbox so not much in it.

Dave Wilkinson · Aug 14, 2006

Kristian,

I would suspect something is amiss if you are registering those noise figures with a "standard" system. Either the baffles have dislodged in one or either silencer or your cat is blown. I would expect the standard 964 to get below 98dB with ease (i.e. half the noise of yours) so I would investigate if I were you. Even with a Cup Pipe I'd be surprised you would reach those levels.

Regards

Dave