Noise Limits on Track Days...
Discussion
Normally my Cerbera 4,5 tests at 105db. At Goodwood yesterday it was the first outing for some custom intermediate silencers made by Joospeed. I was gobsmacked at the 92db noisetest score.
As anyone who was there will know they didn't seem to hold the car back. The only car I encountered that was quicker was the Radical. Mind you the slicks helped!
Whoohoo Thruxton here I come.
As anyone who was there will know they didn't seem to hold the car back. The only car I encountered that was quicker was the Radical. Mind you the slicks helped!
Whoohoo Thruxton here I come.
quote:
Anyone know who could make some repackable ones that will lose this kind of noice and how much!
Andy,
I have a pair of Techcraft silencers on my Ultima. They're easily repackable (6 allen screws on each), and the difference it makes goes from 117dB empty to 102dB when freshly packed. I had to get them rebuilt by Raven Automotove over the Winter, because the innards had been sort of melted by the flames that lick out of the exhaust on overrun
Mike Sweeney at Raven is a bit of a maestro when it comes to rebuilding/modifying things, so you may find that he'll be able to modify what you already have to make them repackable, and save you a bit of cash.
James
A Merlin silencer on my 911 took about -3-4db off, but still not enough to get on at Combe -it's 100db or nothing. Not so stringent at Goodwood. Thruxton is a joke.
BTW, the noise test with a rear engined car I feel unfair -even pushing the clutch down reduces some of the thrash that will be picked up by a noise meter.
The weather conditions also make a difference -barometric pressure seems to affect the noise too.
The prob is that there is no blanket system of measurement -i.e. Combe -100db at 0.5m,45 degrees, 75% revs; Goodwood -0.75m, 45 degrees, 75% revs -u could always lie about the max revs!!
And they are quite willing to test if you just pop in on a track day.
If anybody is stuck in the Surrey/Berks area for noise testing, I can get hold of a noise meter for a small contribution to my wife's school funds!! e-mail me direct.
BTW, the noise test with a rear engined car I feel unfair -even pushing the clutch down reduces some of the thrash that will be picked up by a noise meter.
The weather conditions also make a difference -barometric pressure seems to affect the noise too.
The prob is that there is no blanket system of measurement -i.e. Combe -100db at 0.5m,45 degrees, 75% revs; Goodwood -0.75m, 45 degrees, 75% revs -u could always lie about the max revs!!
And they are quite willing to test if you just pop in on a track day.
If anybody is stuck in the Surrey/Berks area for noise testing, I can get hold of a noise meter for a small contribution to my wife's school funds!! e-mail me direct.
james said:
I have a pair of Techcraft silencers on my Ultima. They're easily repackable (6 allen screws on each), and the difference it makes goes from 117dB empty to 102dB when freshly packed. I had to get them rebuilt by Raven Automotove over the Winter, because the innards had been sort of melted by the flames that lick out of the exhaust on overrun
Mike Sweeney at Raven is a bit of a maestro when it comes to rebuilding/modifying things, so you may find that he'll be able to modify what you already have to make them repackable, and save you a bit of cash.
James
Do you know a number or were they are based so I can have a word with them.
Thanks
Andy
The last track day i did with my race bike at Brands they measured me through the rev range and it never passed 90db yet down the straight i was measured at 112db.I guess theres so many variations on how they measure although i dare say part of the difference was induction roar and throttle position.On the static test it went to the limiter on about a tenth of throttle where as down the straight it was on full throttle!
exhaust systems?
james said:
They're easily repackable (6 allen screws on each), and the difference it makes goes from 117dB empty to 102dB when freshly packed. I had to get them rebuilt by Raven Automotove over the Winter, because the innards had been sort of melted by the flames that lick out of the exhaust on overrun
James
Does anyone know if this exhaust packing degradation effect is dependent on time or is it more to do with mileage?? I guess with more mileage the packing will get caked with deposits, but there again it could be the material drying out and getting less absorbent over time....
went as a track day passenger to Donnington in
a catless modied road going flaming Viper GTS, after 2 laps the black flag came out after 120 Db's was measured, up by the pit wall, they said 100 was limit on this day, so the driver was told to take it easy and keep off the revs along that point (they only took readings there) and was allowed to carry on
>> Edited by viper on Wednesday 13th November 16:32
a catless modied road going flaming Viper GTS, after 2 laps the black flag came out after 120 Db's was measured, up by the pit wall, they said 100 was limit on this day, so the driver was told to take it easy and keep off the revs along that point (they only took readings there) and was allowed to carry on
>> Edited by viper on Wednesday 13th November 16:32
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