Gents, please be aware that the ACU piston speed to calculate the rpm for nosie test purposes is 11 metres per second for 4 strokes (13 ms-1 for two strokes)typically noise test engrs ask for too high an rpm for our long stroke motors.

Just calculate the rpm to give you this piston velocity, the noise testers at Oulton Park were quite approachable and agreed with me.
Otherwise they wanted to noise test my Firebolt at 5000 rpm.

The details of the noise test procedure can be found on the ACU website, you can always ask to see the meter calibrated.

Good Luck

"Passed" the Cadwell noise test with my V&H once but only because the tester took pity on me. Don't want to chance it again, so have made it possible to install a DB baffle just for the test for the next Cadwell track day.