They were just testing a new system for noise checks (similar to the way rally cars are tested), no-one would have been caught. Would be good to have a more reliable system, especially at Finke!
From what I saw, the Chief scrutineer held a noise measurment instrument approximately 1 metre away from the exhaust and got the driver to rev the engine up to what seemed to be mid range revs.
Looked to be a strange system, as some cars seemed to rev harder then others, it would be easy for the distance from the exhaust opening to be different, etc. Also not sure how having twin exhausts may or may not effect the reading gathered.
I saw this from a bit of a distance, so it may have been more involved than this.
The new noise test procedure is under "trial" for the remainder of 2007 with the possible implementation officially for the start of 2008.
It is a static test similiar to what is used in rallying and as it is a static test and therefore conducted under more controlled conditions it is an inherently more consistent and fairer method than the "at speed" test currently used.
The reason some vehicles are revved up to different test points is that different configurations of engines have different predetermined test points. So a V8 engine may have a different rev test point than a 4 cylinder or V6 turbo, etc.
If you want more detail, i am sure a more detailed outline of this "trial" method is included in the minutes from the latest AORCom Meeting held in August. This should appear on the CAMS website within the next few days.
