Wakefield Park Noise Limits

23 March 2016 / David Lawler

With the inevitable encroachment of suburbia on most race tracks, the noise from vehicles using those tracks will over time become an issue. This has unfortunately contributed to closure of many race tracks, and is now becoming an issue at Wakefield Park.

First some background. Car noise limits are often expressed as a sound level in decibels (db) measured at a given distance from the vehicle driving by, usually 30 metres. The decibel scale is logarithmic to model human perception of sound volume, and so an increase in the measured sound level of 3db actualy means a doubling of the perceived sound volume. So as an example, 93db is twice as loud as 90db.

For most road registered cars, Australian Standards specify a drive-by noise limit of 75db. CAMS rules have for many years specified a blanket limit of 95db for competition vehicles, which is more than 6 times louder (ie 20db more) than the Australian Standard for road vehciles. This 95db limit has applied to MX-5 Club track days at Wakefield Park for many years.

From the start of this year, club track days at Wakefield Park will be limited to 90db. Their personnel will measure the sound level of any vehicles of concern, and if a vehicle exceeds the manadated limit, the competitor will be given a warning. If that vehicle again exceeds the limit at that event, it will be excluded from further partitipation. These new noise limits should not be an issue for any road-registered cars, and will likely only affect some dedicated race cars.

Please note that the new 90db limit at Wakefield Park is for club track days, and does not apply to NSW Supersprints which still have a 95db limit.

If a competitor receives a warning over the noise level of their vehicle, they have 4 options:
1. Modify the exhaust on the vehicle, eg add a baffle, packing in the muffler
2. Change the tune of the car, eg reduce red line RPM
3. Change driving method, eg short shift to avoid reving the car, or
4. Leave the event.

If you have a serious concern that your competition vehicle may exceed the 90db limit at Wakefield Park, you should make preparations to temporarily reduce the noise level in case you receive a noise warnng at a club track day.

My race car (White NB #87) has been measured at just over (!) 90db, and so that the car can be used at Marulan Driver Training Centre (which has a 90db limit) I have a baffle which can be inserted in the tail pipe, and also some stainless steel wool packing which can be wrapped around the baffle if additional noise abatement is needed. These noise reduction measures are of course temporary and can be removed when the car is used at events with a 95db limit.

The next Wakefield Park track day is only 2 weeks away, so if you have a race car which may exceed 90db I urge you to investigate your options for noise reduction.