Discussion
I measured mine according to the RAC motorsport directions ( 1 metre from tail pipe at same level and at 45° from it, 2/3rd revs) and it came out at 100dB @ 4000Rpm. So you may be allright depending on the circuit's noise level. Mines a 3.9ltr lump with much mods and a new but standard 350 exhaust. Bear in mind that a 3dB drop is roughly half the existing sound pressure, so you need a lot of extra silencing to get from 100 to 97dB.
Matt
i attend most club track days each year in my 400se i have failed noise tests without baffles at a number of circuits. mine seems to run around 109db at 2/3 revs and most cicuits wont accept this. Tower view race in london made me a track day silencer which you can stuff with wire wool to further reduce the sound. this seems to get it down to 100db i dont attend track days with 98 or below db limits. i have found the best way to pass the noise tests is to keep the revs down!
JES I have to get mine measured. Hope to get it sorted for next year. Several choices have been given to me on this thread, thanks to all.
On another point,does the exhaust make the noise or the motor. My point is a 4ltr or 4.2 with attitude with a 400 exhaust (until I get it measured I won't know)
On another point,does the exhaust make the noise or the motor. My point is a 4ltr or 4.2 with attitude with a 400 exhaust (until I get it measured I won't know)
450SE - 113db @ 4700 and 108ish@4500 So..... Merlin Motorsport external muffler usually takes it down to around 101-103. On stricter circuits I have a Tower View insert in as well which takes it down to under 100 (last time at Combe it was 97).
Never really noticed too much difference in power just a loss in that beautiful V8 sound :-(
Never really noticed too much difference in power just a loss in that beautiful V8 sound :-(
The beauty of noise tests on track days is that it's the word of the tester on the day and the reading on his meter that counts 
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That's why I've got 3 silencers for my SEAC - each one reduces the db by a little bit more and the bolt safely and securely onto the pipe and in one case additionally suspended from within the boot.
I lose about 4db with my small "bomb" - 6-7 db with my large "bomb" and a whopping 10-11 db with my "dustbin". All made by ACT Performance Products.
With the "dustbin" the only way I can tell the engine is running is by looking at the rev counter. :-)
I still have a great track day with any of the silencers and don't suffer from extreme power loss or choking of engine efficiency.
Sean
. That's why I've got 3 silencers for my SEAC - each one reduces the db by a little bit more and the bolt safely and securely onto the pipe and in one case additionally suspended from within the boot.
I lose about 4db with my small "bomb" - 6-7 db with my large "bomb" and a whopping 10-11 db with my "dustbin". All made by ACT Performance Products.
With the "dustbin" the only way I can tell the engine is running is by looking at the rev counter. :-)
I still have a great track day with any of the silencers and don't suffer from extreme power loss or choking of engine efficiency.
Sean
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