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Posted

Anybody got any actual experience of fitting an extra silencer to a one out sport exhaust. I always register 102dB but I am attending an event that has a maximum 98dB. There is only 2 inches of exposed exhaust to clamp on to. I have looked at ACT track silencers and decibeldevils but have no real life info. Thanks, Steve

Posted

I used something very similar looking to the decibel devil at Goodwood once.

A chap rented me one for £25. The car dropped 2-3db for the static test but got pulled up on drive-by as soon as warm up lap was over. The marshal told me that more often than not the straight through type still fail drive-by. From what I learnt, I'd say stick to 100db+ events.

Posted

Thanks for your reply. I usually only do 105dB days at Goodwood but this 98dB is a special charity day and is only open to 98dB cars so as too allow the max no. of cars on the circuit at any one time.

Posted

A totally standard 3.2 should be at about 98db, but not sure if that is what you have given you test at 102db. If you beat the static test then you are usually fine with the drive by, but I reckon you are going to really struggle to get down to 98 starting at 102 with any insert or bolt on cans. They help to the tune of about 2db as noted above, but that is about all. With the fan and induction noise on 911s to contend with as well, you are fighting a tough battle.

  • 2 weeks later...
Posted

Attended a test day at Goodwood for the forth coming 73rd.Members Meeting. Quite a few cars had a devise called Supertrap to lower the dB limit. Spoken to a few and it reduces by around 5dB with no increase in engine temp. I will try this in May and let you know. It might be useful info. Incidentally met Chris Harris who was testing a very early 901 in prep. for the MM.

Posted (edited)

I've go one of those you can borrow for the sound check if you are near enough to me in Bucks to collect.

 

and it does work to bring the Db down, but wouldn't leave it on for the whole day as the back pressure will blast it off under hard acceleration (which happened to me nearly killing a Marshall!)

Edited by BenC
Posted

Quite a few cars had a devise called Supertrap to lower the dB limit.

They can certainly cut the noise, but are very restrictive if you go for a good reduction.

 

Originally designed as a "tuneable" exhaust for motorbikes, they are also approved as "spark arrestors".

 

Mark

Posted

one of these? http://www.ebay.co.uk/itm/Supertrapp-5-12-Disc-Clamp-On-Silencer-3-5-Inlet-Track-Dat-Noise-Reduction-/300812353220

 

bit pricy :wacko:

 

what track is it at 98db? Donington lists 98 but that's a drive-by rather than static. Think Rockingham and Croft also have low static tests. Stupid council rules :rant_yellow:

Yes, thats the kit. Its a charity day at Goodwood and the organiser wants 20 cars on at a time (98dB day) rather than just 10 on a 105dB day.

I've go one of those you can borrow for the sound check if you are near enough to me in Bucks to collect.

 

and it does work to bring the Db down, but wouldn't leave it on for the whole day as the back pressure will blast it off under hard acceleration (which happened to me nearly killing a Marshall!)

Thats a kind offer but I am in Cornwall ! I noticed that most had tag welded the plate to the exhaust and then attached the discs and bolted them to the welded plate.

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