View Full Version : Exhausts and DB noise levels
I am having trouble with my competition exhaust thats a bit too noisy, its a 2 1/4 inch diamter pipe, its got bags of pressure going through it which prooves the engine is breathhing in well but not getting the gasses out as good. It wa stested at OULTON at 102 db static test. Its also burnt of some of the powder coating!!!
Im having a large cenre silencer fitted to see if this helps, if not a 2 1/2 inch system may need to be made up.
What exhausts are others using on there race/track cars? And what DB readings are you getting?
im not 100% sure what mine was but at donington in feb it was a 98db drive by limit, and didnt pass over that, i run the mongoose system with decat and supersprint manifold, i cant remember the exact diameter but the mongoose is bigger then the scorpion/devil systems ive had
btw scoprion with same decat/manifold only hit 86db static at oulton and my mongoose is abit louder! lol
ok i think the mongoose is a 3 inch system isnt it?
Have you got much back pressure?
mongoose is 2.5 or 63mm system..
What about taking a your cat along to trackdays, if its a bit loud bung the cat on, ok it saps your power, but atleast you can do the day, then sort the problems out later
an idea yes but i dont have a de cat pipe i have a straight through system made up especially for the car...
I have a Supersprint manifold, decat and a straight through devil cat back system 2" bore.
And thats been recorded as 98db.
mine was 100.something at cadwell in 06. that was static @ 4krpm and since then ive had another silencer added.
Ive had another centre section silencer added today, has lowered it a bit but when you open the engine up it roars!!!
Will have to wait till i can get it properly checked out at a track day or someone with a noise meter.
Mines 96db @ 4k just got a rear silencer on the Cup racer.
Never been a problem.
Your issue will be induction noise, only solution is airbox on the ITB's.
Robertio
26-05-2008, 23:17
Ive had another centre section silencer added today, has lowered it a bit but when you open the engine up it roars!!!
Will have to wait till i can get it properly checked out at a track day or someone with a noise meter.
If you only need it for a couple of days I have one I could post down to you - just cover postage and I can send it down.
I'm having similar problems as I just finished my track car and it is showing 108db at 4.5k rpm :oops: through a straight 3.5" exhaust. Some silencing is pending once the new clutch turns up and I can actually drive it. It took me a while, but I got my old 500bhp RX-7 down to
Idle: 83db
4.5k rpm: 90db
6k rpm: 93db
Through a 3" system (being turbo'd helped a bit). So it should be possible to get the volume down, just a matter of the right level of silencing in the right place, problem is it tends to add a fair amount of weight.
how and where did you get it checked? can it be done as a check before say i drive all the way to germany only to find its too loud? :P
how and where did you get it checked? can it be done as a check before say i drive all the way to germany only to find its too loud? :P
how and where did you get it checked? can it be done as a check before say i drive all the way to germany only to find its too loud? :P
couldnt an mot centre do it?
stevie_b
27-05-2008, 14:47
Not unless the MOT centre has a dB meter, and I can't think that many would. I've got one I could bring along to RWS, if you are going to that in a couple of weeks? Failing borrowing one just rock up to any race/sprint/hillclimb meeting and there will always be a scrutineer there with one that will probably happily measure your car if you tell them you are thinking of competing it in a future event.
If you think you may be over the limit at an event you can buy a 'bung' that you just stick over the end of the exhaust to lower it. I use that on my cars as they are fine at circuits with 105dB limits but I kept getting thrown off Goodwood which has a strict 98dB limit so need to quieten it down pretty much just for there and then can take it off again.
coops ring easytrack up, they will do a static test if you pop along to a trackday, dont have to be booked on for that tackday aslong as you ring before hand
Ok thanks for offer of sound metre, will be in touch when i have finished a few things.
I wont be able to check drive by noises but static test should be ok.
At oulton last week they asked for 4800 rpm, i couldnt get it to stick at 4800 so think he measured it at 5400 rpm and it made 100 DB so sure it may get 98db at 4800.
The only next idea is to change the exhaust to a 2.5 inch system with a big east to west silencer at the rear.
http://cgi.ebay.co.uk/Professional-7-Range-Audio-Level-Meter-50-126db-decibel_W0QQitemZ120271108960QQihZ002QQcategoryZ40 004QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
much cheapness :D
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