jonnyk5614 Posted May 10, 2012 Share Posted May 10, 2012 I seem to recall seeing some club chat a while back about this. I was wondering what is the best method of quieting an exhaust a little to pass noise tests on track days without adversely affecting tuning too much. Cheers Link to comment Share on other sites More sharing options...
StagNL Posted May 10, 2012 Share Posted May 10, 2012 Is the sound measured with the car at standstill in the paddock or on the track with measuring euipment at trackside? If the latter, just get the last bit of pipe to point away from the measuring equipment. Link to comment Share on other sites More sharing options...
Clive Posted May 10, 2012 Share Posted May 10, 2012 From what I saw, adding an extra silencer bolted on the back of the existing. May look odd (some VERY odd) but there are alternatives. Bike db killers, easy, neat but will sap power, or I am wondering about using a simple fine mesh extension to the existing silencer, hopefully to disperse the sound better. But whatever happens, if you do not pass the test, at best you will waste time finding/hiring extra silencers, or go home, wasting a lot of hard earned. So best to be prepared, even at the expense of power.Ought to add that out toledo only just (1db!) passed at goodwood. That has a std front silencer, and a cherry bomb at the back, fitted by one of the previous owners. However, I have never thought the car "loud" so was pretty surprised. Link to comment Share on other sites More sharing options...
piman Posted May 10, 2012 Share Posted May 10, 2012 Hello Jonny, this is one compact solution, not the cheapest of course seeing it's source?http://www.demon-tweeks.co.uk/motorsport/universal-exhaust-silencers/supertrapp-disc-only-clamp-on-silencers.Alec Link to comment Share on other sites More sharing options...
Clive Posted May 10, 2012 Share Posted May 10, 2012 That's interesting...only because I have a nice stainless supertrap silencer I picked up a while ago, fortunately nice and cheap. When it arrived and I looked it over, I could not believe it isn't VERY restrictive. There seems very little space for the exhaust gasses to actually leave,no matter how many extra plates you added. Or have I missed something? the website reckons they are great to hundreds of bhp, but I really have my doubts. Maybe I should try it on the Toledo? Link to comment Share on other sites More sharing options...
Richard B Posted May 10, 2012 Share Posted May 10, 2012 cliftyhanger wrote:the website reckons they are great to hundreds of bhp, but I really have my doubts. Maybe I should try it on the Toledo?Snakeoil? :X Link to comment Share on other sites More sharing options...
JohnD Posted May 10, 2012 Share Posted May 10, 2012 I have a piece of pipe that will just slide over the end of the exhaust pipe. An internal fit would do as well, and a simple self-tapping screw will secure it.The pipe has two bolts though it at right angles, and the space between can be filled with wire wool. Just enough to satisfy the circuit regs. Lasts long enough for a track day, and you can restuff it any time.John Link to comment Share on other sites More sharing options...
jonnyk5614 Posted May 10, 2012 Author Share Posted May 10, 2012 Cheers for the help guys - it is actually for the Auckland University FSAE car for when we inevitably fail the static noise test :DWe tried a perforated pipe insert, pressed down to a point.... It didn't really work!www.fsae.co.nz Link to comment Share on other sites More sharing options...
thescrapman Posted May 10, 2012 Share Posted May 10, 2012 If the test is a static one from 1m or similar then they can be passed by very very carfully raising the revs up to the test point and very carefully back down again, that way it doesn't "spike" the noise-o-meter.Mr Helm is very adept at doing that in the TR6, which has quite a loud exhaust on it, but never get close to failing.CheersColin Link to comment Share on other sites More sharing options...
jonnyk5614 Posted May 11, 2012 Author Share Posted May 11, 2012 We are running a custom V single package. 450cc is kicking out 65hp. Trust me, this thing is loud! The test is at idle......our idle being at 5000rpm or so :D Link to comment Share on other sites More sharing options...
JohnD Posted May 11, 2012 Share Posted May 11, 2012 Jesus, Johnnie, I've heard of getting your Dad to do your homework, but this is a bit much!You are part of the University of Auckland Formula SAE team, competing in the official, International, indeed Global, contest for small, student-designed race cars, and you want us to advise you on silencing?Away with you, you soncy student. Away to the library and your tutors and to do some work!Research on silencing is badly needed - little seems to have been published since Smith & Morrison http://www.amazon.co.uk/Scientific-Exhaust-Systems-Engineering-Performance/dp/0837603099/ref=sr_1_2?s=books&ie=UTF8&qid=1336723483&sr=1-2 and they showed that more is to be gained by tuning the pipes than fiddling with the silencer.You could be in on the ground floor! Exhaust Professor of Silencing?John Link to comment Share on other sites More sharing options...
jonnyk5614 Posted May 11, 2012 Author Share Posted May 11, 2012 Haha - we were going to but not our priority at the moment. Noise is only measured in a static and at the skid pan test so something we can quietly remove isn't a problem! We were gong to test a couple of concepts and do some research but then I remembered some chat from a while back about the various means people had to take at Goodwood :D Link to comment Share on other sites More sharing options...
uksnatcher Posted May 11, 2012 Share Posted May 11, 2012 Most systems have a small silencer/can half way down the system, whats the benefit of this, seems useless? Always wondered??? Link to comment Share on other sites More sharing options...
ferny Posted May 11, 2012 Share Posted May 11, 2012 That's a resonator box. It'll absorb a lot of the high notes me thinks. My acclaim doesn't have one, if you've ever heard it. Link to comment Share on other sites More sharing options...
Beans Posted May 11, 2012 Share Posted May 11, 2012 cliftyhanger wrote: ... a nice stainless supertrap silencer ... Or have I missed something? ...According to Divad Vizard The Super Trapp's performance leaves much to be desired ... by the time noise has beenreduced to the level produced by an effective silencer the power output of the Super Trapp equipped engine is way down. Link to comment Share on other sites More sharing options...
Clive Posted May 11, 2012 Share Posted May 11, 2012 A slight misquote :oBut that seems fair enough, without the rear plates attached it would be a very minimal silencer, and with teh discs probably useless. Looked at it today, the actual area for the gases to escape is really small. Hopeless. Link to comment Share on other sites More sharing options...
jonnyk5614 Posted May 12, 2012 Author Share Posted May 12, 2012 uksnatcher wrote:Most systems have a small silencer/can half way down the system, whats the benefit of this, seems useless? Always wondered???Already have a silencer - spent Thursday night making a new one! They are quite effective though - even the straight through ones. The gasses get to the box and go "whoopie, we can spread out and depressurize!" only to discover that they run straight into fiberglass wool and all the energy goes. Link to comment Share on other sites More sharing options...
uksnatcher Posted May 12, 2012 Share Posted May 12, 2012 1045 wrote:The gasses get to the box and go "whoopie, we can spread out and depressurize!" only to discover that they run straight into fiberglass wool and all the energy goes.So manufacturers can fine tune the exhaust note without any flow restriction at certain revs/loads etc by adding a different sized/length resonator of this type? Link to comment Share on other sites More sharing options...
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