Measuring exhaust dB

[sixspeed]

Hi,

I've just had a new exhaust fitted, and have a sound meter. What's the correct way to measure the sound level (the same method's they use on trackdays) so I can see if I'll have any problems getting onto particular circuits?

IIRC, it's measured at 1m? And at 45 degrees to the exhaust (pointing down at the exhaust tips?). Is that correct?

Does anyone know whether I should be measuring with A or C weighting on the sound meter?

Edited by sixspeed on Thursday 12th July 12:34

[tjdixon911]

1m @ 45degrees sounds about right, I think it is then measured at 3/4 revs...

[Naughty Magpie]

All I know is that I had a friend measure my car with his dB meter and it was 100dB & when I got to the track it was suddenly 105dB. Luckily they still let me on.

[richardb.jones]

A bit hit and miss tbh - I was watching them test cars yesterday @ Snetterton and the guy was almost poking the meter up the pipe ... :-(

So if you're borderline, I suggest you have a chat with the testers to ascertain how they are going to test it first before you get your red sticker ...

[ian964]

tjdixon911 said:

1m @ 45degrees sounds about right, I think it is then measured at 3/4 revs...

It's normally 50 cm at 45 degrees and 3/4 revs. I think it's usually db(A), so use the A weighting rather than C.

Edited by ian964 on Thursday 12th July 19:22

[muckymotor]

Whenever I've had my car tested the meter has always been attached to an angled arm so the distance is spot on every time.