ARM-Scooby

Morning all,

I am doing a track day this year with a 98db limit. I have a firestorm on at the min and i think it might be too loud.

Any advice on a exhaust that will still give the scooby burble but at the same time pass any sound checks.

Cheers,

Andy

Jay m A

iTrader: (2)

I am biassed. But have a look here http://bbs.scoobynet.co.uk/showthread.php?t=424076 and in particular my comments in #17

Its a TSL group N, if you ring them they may have information on dB levels.

The exhaust was on the car when the previous owner did quite a few trackdays, including Donnington's strict limits.

hades

98dB measured where and how? 98dB drive by at 20m is a lot different test to 98dB 1m from the tailpipe at 5000rpm, for example.

If the test is using "a" weighted dB measurement, at 2/3 maximum revs (call it 5000rpm on a scoob) at 1m behind tailpipe 45º to tailpipe and on a level with it - this is one of the most common tests, then there are quite a few backboxes that would pass, and still sound decent. I've measured with a calibrated dB meter my APS system and a Prodrive WR Sport, both of which are well under, and yet certainly give plenty of burble. Other quieter systems include the Remus, MRT (the quietest box I have some any figures on - 87dB at 20" directly behind the tailpipe - which is a common US test), H&S will definitely do you a quieter one if you ask. I expect the likes of the Ninja, Group N, Magnex etc will still all pass, whilst being slightly louder than the first few I mentioned.

Roojai

I think a lot of places measure from 50cm from tailpipe.

Jay m A

iTrader: (2)

At Goodwood, which is aguably the hardest place to pass, the limit is 98Db measured at 3/4 max rpm, 1m behind and 1m above the exhaust exit. A few scoobs had problems on the day, my Westfield just scraped by due to my 'conservative' recollection of my max rpm. Indeed I had to sort shift by the sound meters dotted around the track to keep them happy. At least at Goodwood they 'want' you to pass, unlike other venues.