Track day noise limit 100db on a stock exhaust

[overhere]

I did the Abingdon track day today with Motor-Sport Events, what a brilliant track, and awesome day! When I arrived they did the sound level test and I failed! limit 100 and I measured 103! I was so bummed, I spoke to the organisers and they agreed to measure me again after the warm up prosession, I did rev it a little tiny bit more carefully, the guy came up after 3 or 4 measures and said I've just squeaked by, 99.4.

I don't know if he was being lenient or the first reading was that far out, I know you can buy cans to calmp on (A Cerbera and T350 had them) but I'm not sure I'm happy to do that, my exaust is so tidy and shiny I don't want to scratch them.

Just curiuos if anyone has had this experience and if I do another track day with 100db limit am I likely to fail?

Cheers

Jack

[biggiles]

I did a track day back in August with a similar 100dB limit.

The noise level on my 500 varied enormously depending on where it was measured from.

If you can measure it from the side, it will be much less than if measured between the 2 exhausts.

Most "testing guidelines" are for a single exhaust/two together- so you can expect some flexibility with two exhausts far apart.

I got through on the second or third time.

You can buy baffles for about 100 quid for two - try Castle Combe motor shop or ACT.

[tvrbob]

100db is ridiculously low. The V8's always register above 100 on the standard track test but S6's, even with sports exhausts register under 100. I'm surprised therefore that an S6 needed cans.

[Graham]

interesting my 4 ltr chim with standard exhaust but no cats, consistantly measures 97-98 db ?????

[bobs4c]

My Chimaera 450 has a standard exhaust. It has been passed at Castle Combe (100dB limit) at quite a safe margin. Failed twice at an MSE event, but sqeezed through at Colerne in October at 99.6dB. Bought some bolt on silencers and take them - just in case. MSE have failed quite a few Tivs from our region (C3C).

Bob

[zumbruk]

Weird. My 1997 Chim 450 consistently measures 96dB - and it gets measured at every sprint, so it's been done some 25 times in the last three years, with the exception of one this year who reckoned 102dB.

[lil smithy]

tvrbob said:

100db is ridiculously low. The V8's always register above 100 on the standard track test but S6's, even with sports exhausts register under 100. I'm surprised therefore that an S6 needed cans.

you saying spd 6's are quiet:BIGLAUGH:cause my dads tamora measured 108 db under 3000rpm at bruntingthorpe but that does have decats as well as sports exhausts but it got the same as a 4.2 cerbera with decats and supersports exhausts

[tvrbob]

lil smithy said:

tvrbob said:

100db is ridiculously low. The V8's always register above 100 on the standard track test but S6's, even with sports exhausts register under 100. I'm surprised therefore that an S6 needed cans.

you saying spd 6's are quiet:BIGLAUGH:cause my dads tamora measured 108 db under 3000rpm at bruntingthorpe but that does have decats as well as sports exhausts but it got the same as a 4.2 cerbera with decats and supersports exhausts

The S6's have a very different sound. Much more of a growl/roar than the pop/bang of the V8's. I've been measuring db at TVR gatherings for a few years now and the facts speak for themselves. S6's sound loud but measure lower that one would expect event with exhaust mods they don't reach the dB values of the V8's. dB is a log scale so 110dB is twice as loud as 100dB. I have measured Cerbera's at 130+ so 108 may be loud but there are significantly louder TVR's out there.

[overhere]

Thanks for all the reply's! I thinks I'll just wing it again next time rather than buy the bolt on cans.

Thanks again

Jack