Track-Day Noise Limits

[kentsmudger]

Can anyone tell me the procedure used to check noise levels at track-days. I am booked to go to Brands Hatch on Friday, and the driver's info pack states - "Your vehicle must pass a static noise test of 105dB". There is no mention of a drive-by test on the track, as used at some circuits.

We do public address systems at work, so I borrowed an SPL meter tonight to check mine. Standing directly behind the car about 1 metre away, we recorded 75dB at tickover, then revved up to about 6,000 rpm (engine nice and warm after driving 30 miles to work) and got 102dB. This was in the open air in the car-park, but not very far from a building, so there may have been some reflection adding to the measurement.

I know the scrutineering bay at Brands is in an open-ended shed. If they test inside this, the level recorded may be higher.

I am concerned that I may be a bit close to the limit, although I realise that the scale is logarithmic, so maybe not that close. Does anyone know how close to the car they measure from or if the test is at full throttle as we did?

[Anonymous]

0.5m from exhaust at 3/4 max rpm. You'll be miles under with your setup, don't worry.

[markiii]

indeed bear in mid that db is lgrithmic, each 3db is a doubling of volume.

The loudest Hass turbo only just reached that noise limit, so on an almost stock car you will be fine

[kentsmudger]

Thanks for that - I was hoping that was the case!