Japspeed with decat db?

[A.BLAKE]

Any one know roughly speaking what the db level on a japspeed with decat would be? would it pass for track use?

[dantheman]

I knew you'd ask this

I cant answer your question but it wont fail an event with a 105 dB limit. Go to one of those, ask the testers there how loud your car is, then you'll know for next time. Although bear in mind these are petrolheads, its not a science experiment. If you go to one track and they tell you its 98, the next track might tell you the exact same car is 101. I doubt they calibrate their readers.

[captain_codpiece]

I would also be interested what the Db is on one of these, I am thinking of running one.

Cheers

Lloyd

[SonicSW20]

I knew you'd ask this

I cant answer your question but it wont fail an event with a 105 dB limit. Go to one of those, ask the testers there how loud your car is, then you'll know for next time. Although bear in mind these are petrolheads, its not a science experiment. If you go to one track and they tell you its 98, the next track might tell you the exact same car is 101. I doubt they calibrate their readers.

The readers themselves rarely need calibration - certainly not to the point where they are going to be 3dB off. Unless its a very cheap unit of course. The difference in readings is more down to the environment. Is it hilly? Is it windy? Low pressure or High pressure day? air temp? All makes a some amount of difference, and the whole lot added up can give a substancial difference.

[dantheman]

The readers themselves rarely need calibration - certainly not to the point where they are going to be 3dB off.

With all due respect i one million % disagree. i did a driveby noise test recently using one of the best models of handheld sound meters money can buy. 2 units were calibrated using a 114dB @ 1000 hz pistonphone. One reader said it was 115.2dB, the other said it was 111.6dB.

Either way as you say there are many factors that can very a reading, so the number is not absolute, its relative.

[Lauren]

The issue is that for ever 3 db increase is about twice as loud, so it'd be miles and miles out to get that kind of difference. More likely to be user error I'd say.

In terms of Db I'd say get an exhaust that isn't over 95db at .75m from the exhaust tip at a 45 degree angle (as that is generally how noise is measured). As you can probably guess there is a good amount of room for user error here!