PDA

View Full Version : Noise



Mr E
09-15-2007, 06:08 PM
The 11 year old bucket of bolts sailed through another MOT today - no worries at all.

Every year, the emissions test usually draws a round of applause (hold the car at 4000rpm for a bit, in a metal shed - it's a bit noisy).

I wondered *how* noisy exactly. For a couple of reasons, while there is no set maximum for a road car, most racetracks have a strictly enforced limit. And conversations can end up in dick measuring contests without any actual measurements being taken (so to speak)

So I got hold of the appropriate kit, held it at about a meter away outside with no walls to reflect sound off, not in direct line or pointing at the exhaust. And Sarah held the car at 4000rpm for 10 seconds or so.

102.8dBA. Eeek.

My local track is 105dBA at half a meter away and 3/4 of the redline (so 4500rpm). So it's going to be tight - I suspect I'll need the additional silencer.

For reference, the Alfa (which is not a notably quiet car in the grand scheme of things) recorded 91.8dBA at 4000rpm.