How to measure volume?

[sbyatt]

Does anybody know whether there's a particular method to measure the decibel level of a bike and/or car for a track day? I don't really want to turn up to a 95db limited day if my car makes 104db! Is it checked during scrutineering? Is the sensor placed next to, behind in front of the car? At what revs? Or is there a mic on the track and you're pulled off if you're too loud? TIA, SB

[patrick]

quote:Does anybody know whether there's a particular method to measure the decibel level of a bike and/or car for a track day? I don't really want to turn up to a 95db limited day if my car makes 104db!

Generally, the mic is placed behind the car, 0.5m from the exhaust, you are then asked to rev the car (normally to 4,500) and the noise level is taken at this point. If in doubt get a silencer, for about £80 and some wire wool. That way, if it's a bit too noisy, stuff more wire wool up the pipe. Edited by PetrolTed on Monday 15th January 17:20

[Mike Bees]

Castle Combe and Goodwood test at 3/4 max rpm, which is a bit of a bugger if your engine revs to 9000. The test is take at 0.5m from the end of the exhaust at an angle of 45 degrees. Stuffing wire wool up the pipe might get you through the static test, but it'll blow out in seconds when you're on the track and may result in you failing the drive-by monitoring at Goodwood & Combe. Mike

[AdamB]

Any opinions on which is the best volume reducing exhaust insert. I want to come down from about 113 to 98 for Goodwood.

[PetrolTed]

That's a hell of a lot to come down. A potato?

[AdamB]

I tried my local Tescos and the 'Fruit and Veg Manager' could not guarantee that his produce was of the correct consistancy for track days. He thought under normal driving conditions that I should be OK but suggested a specialist supplier for track events. What now...........?

[Mike Bees]

113 to 98? Highly optimistic, you'd have to bung the exhaust up so much that the engine will become very unhappy. You need more silencers, not inserts! Mike

[GreenV8S]

Cirks manages something like this with his 450 using an internal Tower View insert together with an external can from (I think) Merlin Motorsport. Peter Humphries (and a green V8S)

quote:113 to 98? Highly optimistic, you'd have to bung the exhaust up so much that the engine will become very unhappy. You need more silencers, not inserts! Mike

[AdamB]

Thought I'd post the results of the potato experiment. With the tower view inserts in I recorded 106db so couldn't go out to play. Had the car retested with no inserts in and recorded 125db at 5300. (Had it tested again to check and it was 125) Any one know a good source of second hand standard exhausts for track day use.? Edited by AdamB on Tuesday 20th February 09:12 Edited by AdamB on Tuesday 20th February 09:13

[fourwheeldrift]

Christ AdamB what have you got a Tornado Jet????

[hughesie]

You cant talk Mr FWDrift !!

[AdamB]

Normal'ish Cerby 4.5 on the road & a pair of running shoes for the track.

[Mk1]

Having spent 15 years on Tornado Jets (+gulf 90-91)i can assure you all that in full reheat they are in excess of 130db. And yes i am a bit deaf! Good luck with the potato.