Blackbirdman Posted June 24, 2002 Share Posted June 24, 2002 Given the current trend of ever tougher noise limits here and even on the continent I thought I should look at my exhaust system. A test earlier at a Bookatrack day this year showed 115dB at 10,000rpm. The silencer is only 2000 miles old and a standard Caterham non-repackable one. Talking to Balckbird Motorsport 2000 miles is about as long as a standard exhaust will last before it looses too much stuffing. I managed to do a direct comparison between my exhaust and a used but repacked Raceco unit (thanks Ammo). Although the Raceco unit was about 100mm longer than the Caterham unit the improvement was still impressive. Rpm Caterham Raceco 2000 90dB 84dB 4000 100dB 89dB 6000 107dB 93dB 8000 110dB 101dB 10000 116dB 104dB As most tests are now done at ¾ max revs (8800) I would stand a good chance of getting on at Goodwood which I have missed out on for the last few years due to noise worries. Looks like that’s more money just to keep the locals happy then. Do you think if we all brought houses next to Heathrow and then complain about the noise they would shut the airport down? Then the house prices would rise, hey maybe this is an investment opportunity! Matt Is it a bike? Is it a car? No it's Blackbirdman cool.gif Link to comment Share on other sites More sharing options...
Morls Posted June 24, 2002 Share Posted June 24, 2002 And we can have cheap track days on the runways and taxi roads smile.gif Mark Link to comment Share on other sites More sharing options...
Gary Furst Posted June 25, 2002 Share Posted June 25, 2002 Blackbirdman Do you have the contact details for Raceco? Thanks Link to comment Share on other sites More sharing options...
mr_ed Posted June 25, 2002 Share Posted June 25, 2002 Yes indeed, I'm interested to know what size this Raceco silencer was. My blackbird measured 117dbs once, didnt harf crucify the passenger as you overtook a tin-top. (reverbed off their door) I'm currently running about 106db using a Micron Road Legal silencer, but like you would like to be ~100db. Cheers, Ed Link to comment Share on other sites More sharing options...
Blackbirdman Posted June 25, 2002 Author Share Posted June 25, 2002 Raceco advertised in the last Low Flying. Sorry don't have my copy with me. Can anyone supply the phone numner? The silencer tested was 6" diameter and about 700mm long with 2" OD inlet. Mixed units sorry! Should be able to fit a 650mm unit on my car. Matt Is it a bike? Is it a car? No it's Blackbirdman cool.gif Link to comment Share on other sites More sharing options...
mr_ed Posted June 25, 2002 Share Posted June 25, 2002 Hmmm, think I'd like to go even bigger than that. Probably a 7inch diameter, and as long as I can get it in, just to be on the safe side and not to have to repack during the lunch break at trackdays! When speaking to Blackbird Motorsport last week, they mentionned they'd just got a 30inch (75cm) long techcraft silencer to be fitted to a Caterbird that _had_ to be able to run at goodwood. Needed the manifold shortening/reshaping to fit it in I think. What pains me is the bigger the silencer, the heavier it is, and whilst my Micron silencer is quite loud, it's very light compared to a 7inch*25inch monster. That said, the baffled design of my micron is possibly lossing me a few bhp. Cheers, Ed Link to comment Share on other sites More sharing options...
Blatman Posted June 25, 2002 Share Posted June 25, 2002 SBD's silencer is large enough (big inlet though....), light, and quiet........... Link to comment Share on other sites More sharing options...
mr_ed Posted June 25, 2002 Share Posted June 25, 2002 Indeed, very nice it is. Just a bit put off by discussions recently about backfires etc. Cos my BEC is carbed etc. Cheers, Ed Link to comment Share on other sites More sharing options...
J.R. Posted June 27, 2002 Share Posted June 27, 2002 Blackbirdman I have yet (touch wood) to have any noise or packing deterioration on my Blackbird Caterham. I only run a 5 inch silencer and my friends complain that they cant hear my car when I am racing or blatting - they think I am not trying. The difference may be that I have cut n shut the Honda exhaust primaries and secondarys. There are two small expansion chambers forming the 2 into 1 sections and these are lined with an metallic laminated acoustic mesh, a bit like wire braid. I think that this takes out the initial high frequency bark before the silencer does its job. Presumably Honda have spent much time & money on these things so when we buy "better" big bore etc stuff there is a price to pay. Have done about 1500 road miles and several races and track days to date. Link to comment Share on other sites More sharing options...
mr_ed Posted June 27, 2002 Share Posted June 27, 2002 JR, Thats very interesting, I've got a stock blackbird manifold lying about, and saw its got a large box when the collector section is. I assumed it had baffle plates in it, and hence would be creating back pressure. Dont spose you've got any pics of the internals? and/or a pic of your manifold? Cheers, Ed Link to comment Share on other sites More sharing options...
Mark Durrant Posted June 27, 2002 Share Posted June 27, 2002 Raceco can be contacted on 07860 494064 or take a look at www.raceco.com. I'm getting a Techcraft silencer fitted in a couple of weeks as my Caterham Competition silencer is getting noiser by the day and is rattling like a goodun! Link to comment Share on other sites More sharing options...
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