Exhaust Decibel Question
Exhaust Decibel Question Heading out for another HPDE in April and the track has a strict 98 db noise restriction. It's measured around the track at multiple points so you can't just let off or turn away from the gauges.
My question: has anyone ever had their exhaust at WOT measured? Any idea how many db you were at?
My mods are in my sig, however it's a heads/cam/intake car with long-tubes, off-road y-pipe, e-cutout in the i-pipe (that I usually leave partially open to increase flow) and a Crapmaster catback. I'm curious what level I'm currently at. I would think with the cutout open I'm going to be close to the 98 db limit (if not over it) although I'm confident with the cutout closed I would be well under.
Anyone have any car specific sound data as a basis for comparison?
My question: has anyone ever had their exhaust at WOT measured? Any idea how many db you were at?
My mods are in my sig, however it's a heads/cam/intake car with long-tubes, off-road y-pipe, e-cutout in the i-pipe (that I usually leave partially open to increase flow) and a Crapmaster catback. I'm curious what level I'm currently at. I would think with the cutout open I'm going to be close to the 98 db limit (if not over it) although I'm confident with the cutout closed I would be well under.
Anyone have any car specific sound data as a basis for comparison?
I raced EDT atv's in the mid 2000's. They made the pro class pass sound. They wanted
us to be at 96db at 3500 rmp. My 06 trx450r tested at 106db at 3500 rpm. Needless to say the whole pro class failed lol. Tim Farr on his ktm was the closest to passing at 99db.
With that being said my ws6 with tsp true duals is louder. It will not pass at black hawk
farms.
There are alot of trick's you can do to make it pass sound, some of them even make
more power. You can shoot me a pm if you want and i'll give ya some ideals.
us to be at 96db at 3500 rmp. My 06 trx450r tested at 106db at 3500 rpm. Needless to say the whole pro class failed lol. Tim Farr on his ktm was the closest to passing at 99db.
With that being said my ws6 with tsp true duals is louder. It will not pass at black hawk
farms.
There are alot of trick's you can do to make it pass sound, some of them even make
more power. You can shoot me a pm if you want and i'll give ya some ideals.
It's a road course. In order to comply with zoning requirements the track has strict sound limitations. This isn't uncommon for non-spectator tracks. It's still plenty of fun to drive on them.
I'd find out from the track at what distance the db level is measured. I'm sure they can help you out with your concerns
Here's the info from the A.M.P. website.
Large track-98 DBA “A” weighted 50'
from track edge under full
throttle, near or at full RPM.
For each doubling of the distance from which you measured the db level you lose at least 3db. So if you measures it from about 20" at a 45* angle (SEMA standard)from the exhaust tip you should get a least a 14db reduction at 50'. Measure the db level in a open area away from buildings.
IMO. a Dynomax Ultra-Flo Welded muffler#17536(about $113) should be almost a direct swap for the fm muffler, plus it'll be quieter and flow better!
Here's the info from the A.M.P. website.
Large track-98 DBA “A” weighted 50'
from track edge under full
throttle, near or at full RPM.
For each doubling of the distance from which you measured the db level you lose at least 3db. So if you measures it from about 20" at a 45* angle (SEMA standard)from the exhaust tip you should get a least a 14db reduction at 50'. Measure the db level in a open area away from buildings.
IMO. a Dynomax Ultra-Flo Welded muffler#17536(about $113) should be almost a direct swap for the fm muffler, plus it'll be quieter and flow better!
Last edited by 99Bluz28; Mar 15, 2013 at 05:44 PM.
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I would check over on frrax.com, since they all have run on multiple road courses, many of which have sound restrictions.
I would expect them to have some answers (unless you've already checked there??).
I would expect them to have some answers (unless you've already checked there??).
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Lol. I ran into this exact problem at snetterton track a few weeks ago. The track's decibel limit is 98 and my car registered at 118 revving the car at 5.5k rpms with their mic by my tail pipes. Failed! However the manager decided to do another round but this time with my car at the straight away driving my car full bore all the way up to 6.8k rpms!! I passed!
Btw, I'm heads and cammed with bolt ons, full exhaust, true duals all the way at the back.
Btw, I'm heads and cammed with bolt ons, full exhaust, true duals all the way at the back.
Last edited by bene; Mar 16, 2013 at 03:42 PM.
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Verdad Gallardo Lol. I ran into this exact problem at snetterton track a few weeks ago. The track's decibel limit is 98 and my car registered at 118 revving the car at 5.5k rpms with their mic by my tail pipes. Failed! However the manager decided to do another round but this time with my car at the straight away driving my car full bore all the way up to 6.8k rpms!! I passed!
Btw, I'm heads and cammed with bolt ons, full exhaust, true duals all the way at the back.
Btw, I'm heads and cammed with bolt ons, full exhaust, true duals all the way at the back.
Thinking I may run to Radio Shack and pickup a sound meter to measure. AMP notes this on their website as a way to get a good idea of where you're at. Probably need to figure out if I need to knock a couple db off or if I'm way out of compliance and need to do something more substantial.
Thanks again!
