Griff Posted February 8, 2003 Share Posted February 8, 2003 Went to Castle Combe and got them to check how loud my new Caterham was. Managed 104dB at 4,500rpm - woops! It's a K-series with Emerald ECU etc and I don't want to mess up all the mapping with an ultra restrictive silencer - likewise don't want to waste money and be barred from track days. Any suggestions? Also the engine is on throttle bodies with only a foam filter so lots of induction noise. Not sure how much this contributes to the overall level when not under load, but guess it might cause problems if it's a drive by test. Never done one of these before, so don't really know what's involved or whether it's more severe? All suggestions gratefully received. As you might guess, new to this and never had a problem with my TVR... Link to comment Share on other sites More sharing options...
puremalt Posted February 8, 2003 Share Posted February 8, 2003 You jest surely. TVR s sound like sewing machines don't they? Mine Farts and Belches Link to comment Share on other sites More sharing options...
Gridgway Posted February 8, 2003 Share Posted February 8, 2003 Apart from the TB's and if you have aggressive cams you will have an induction noise problem. It sounds like your exhaust can is shagged. I put a 7" superlight R race can on a VHPD and got below 98dB. Only solutionn to the induction noise is an airbox. Graham Link to comment Share on other sites More sharing options...
Gridgway Posted February 8, 2003 Share Posted February 8, 2003 BTW I have run at Castle Coombe with said SLR and 7" silencer. So tha twould be the way to go. There are quite a few aftermarket exhausts that would prob work. Graham Link to comment Share on other sites More sharing options...
F355GTS Posted February 8, 2003 Share Posted February 8, 2003 98.6db at 4.5k yesterday with a short BTB silencer added to the std 4 - 2 - 1 bit Mark Link to comment Share on other sites More sharing options...
cdg Posted February 9, 2003 Share Posted February 9, 2003 The noise scrutineers at Castle Coombe are notorious...for being complete w**kers. I bet they suggested you buy a Supertrap add-on silencer from Merlin Motorsport (conveniently sited at the circuit). We have taken Sports 2000 cars there and been over the limit, when at all other UK tracks we have been well within the limit. Draw your own conclusions. Chris. Link to comment Share on other sites More sharing options...
Griff Posted February 9, 2003 Author Share Posted February 9, 2003 One thing's for sure - Caterhams go better but they'll never match the sound of a Griffith at full throttle. That said, thanks to all for the suggestions. Any recommendations on after sales sources for exhausts. Apart from Caterham and Raceco, I couldn't find much else in Low Flying. Griff. Link to comment Share on other sites More sharing options...
Drumster Posted February 9, 2003 Share Posted February 9, 2003 Speak to Chris Wheeler at the 7 Workshop about Techcraft repackable silencers. My x/flow was running at 110db until I fitted one of these and the last time it was noise tested it managed only 97db. Chris Alston 1800 Supersprint - Loud and Proud 😬 ...well it only sounds fast officer 😳 Brooklands aeroscreens for those........flies in the teeth moments Drive it like you stole it! Link to comment Share on other sites More sharing options...
Alias Posted February 9, 2003 Share Posted February 9, 2003 Castle Combe can be a bit of a nightmare as they often test you just outside the entrance to the circuit in an area conveniently surrounded by buildings which reflect the noise of your exhaust back onto the sensor. As others have suggested, would recommend a Bernard Scouse airbox and an SLR exhaust. One car - 1400 Supersport with 6 gears and clamshell wings. Link to comment Share on other sites More sharing options...
Luke Beaumont Posted February 10, 2003 Share Posted February 10, 2003 Griff, just a recommendation for the Raceco can, it's a well made bit of kit. Hethel measured my K VVC at 96dB with it. Link to comment Share on other sites More sharing options...
jonhill Posted February 10, 2003 Share Posted February 10, 2003 104 dB @ 4500 sounds rather high to me. I know readings can vary a lot from day to day, but my SLR's been measured at CC many times and, though the exact figures escape me (101 rings a bell), it was never that high. I've never had a problem getting on the track. I've got the std SLR exhaust, with the CAT replaced with a 4-2-1 pipe. I do recall 104 dB at Oulton Park, but that was at 6000 rpm. Could the Emerald make as big a difference as all that? FWIW I think the people taking the readings are council, and are not connected with the circuit. I suspect the circuit enjoys their disrupting presence about as much as the punters. As to the fact you can buy a super trap from Merlin, well would you rather just go home? However, at one sprint I did there, there was a huge rumpus over the readings. Loads of people were failing who had been tested 6-8 times already that season, with consistent results, and were suddenly reading 4-5 dBs higher. As someone already said, there's a lot of concrete about in the area they test, though I was well below the 105 limit, which seems to imply no funny business to me. Jon Link to comment Share on other sites More sharing options...
Griff Posted February 10, 2003 Author Share Posted February 10, 2003 Thanks all. Been offered the "loan" of a couple of silencers to see how they work and affect performance. Should help with the immediate problem, perhaps in conjunction with a super trap. After that I'll give some thought to a new system, perhaps manifold and airbox as well? Checking the OD of the present exhaust (4-2-1) it's 2.1/8" which seems a little small compared to the 2.1/4" or 2.1/2" standard sizes offered by Raceco and others, especially consider the high spec of the rest of the engine? On the other hand I don't want to mess up the mapping. Any thoughts? Link to comment Share on other sites More sharing options...
James Rogers Posted February 11, 2003 Share Posted February 11, 2003 How does the supertrap attach and how much of a sound difference does it make. Does anyone know the part# so I can look at a catalog. Thanks James F. Rogers Link to comment Share on other sites More sharing options...
Mark Piper Posted February 11, 2003 Share Posted February 11, 2003 Strange - I found a "feature" on my Stack tacho that "seems" to drop the revs readout by 1,000 rpm...can't think what one'd use it for... I'm presuming the noise test was at static using your tacho as the basis for the reading?...incidentally Griff, what car did you end up buying? Link to comment Share on other sites More sharing options...
Gridgway Posted February 11, 2003 Share Posted February 11, 2003 wouldn't you want it increased by 1000? Graham Link to comment Share on other sites More sharing options...
Mark Piper Posted February 12, 2003 Share Posted February 12, 2003 doh! Link to comment Share on other sites More sharing options...
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