Pezky Posted March 27, 2009 Share Posted March 27, 2009 Only just passed noise testing today at Abingdon. 100dB static at 0.5m. First test was 101dB. They kindly tested it again at 99.9db 😬-but told to take it easy on the pit straight in case the environmental health bods are about Limits are getting lower nowadays so want to get it a low as possible in future. Car has a 1700xflow and standard 4-2-1 rear exit exhaust. I assume as the car is 17 yrs old the silencer is not silencing much anymore. Should I just look at replacing the silencer or replace the whole system 🤔 Jonathan Link to comment Share on other sites More sharing options...
Stationary M25 Traveller Posted March 27, 2009 Share Posted March 27, 2009 If it is that old, assume it has a small diameter silencer ? If a CC unit, probably packed with stainless wire, rather than fireglass ? This doesn't absorb noise very well. I have just fitted a 7" dia repackable silencer which is a big improvement over the 6" dia CC unit   Link to comment Share on other sites More sharing options...
jonboylaw Posted March 28, 2009 Share Posted March 28, 2009 Also try checking the exhaust gaskets at the head, if they are blowing you get a lot of high frequency noise here. Replace with a copper set from the 7 workshop and get a re-packable can. Jon Link to comment Share on other sites More sharing options...
John Howe Posted March 28, 2009 Share Posted March 28, 2009 Certainly make sure you are using a repackable can. When it is repacked... weigh it. Then when ever you feel it might need repacking, you can weigh it to establish how much packing has actually got blown out. After a rather noisey return from Bordeaux, a few years back, I went to repacked the silencer and found it was completely empty!  JH Deliveries by Saffron, the yellow 230bhp Sausage delivery machine Link to comment Share on other sites More sharing options...
guilleracing Posted March 28, 2009 Share Posted March 28, 2009 I have a little experience in this. I had a re-packable silencer on an F3 car. After a long life on the car it didn't seem to be doing a lot of silencing. When I opened it up I found the fibreglass material inside had been converted by the heat to a glass tube and was completely fused solid.  Once I re-packed it with new material, hey presto! it worked perfectly again. 😬 The moral of the story is to check the condition regurlarly, I do so once a year and replace as required. Greg. Link to comment Share on other sites More sharing options...
Graham Perry Posted March 28, 2009 Share Posted March 28, 2009 Send your silencer off to that nice Ammo chappy as a template and he will send you a new larger one back again that will be very quiet Lots of happy Raceco customers on here. With a crossflow induction noise is also a factor and you won't really make that less unless you fit injection and an airbox. An airbox is not recommended for carbs due to the fire risk from stand off and backfires. I have fitted airbox/injection on mine and am hoping my crossflow will be about 95-98 db when tested at the next sprint  Edited by - Graham Perry on 28 Mar 2009 11:27:21 Link to comment Share on other sites More sharing options...
akakubi Posted March 28, 2009 Share Posted March 28, 2009 In fact, it was so noisy, it was scaring the army guys at the barracks across the field. 😬 j/k The can does look very slim, however, so that may be a factor.  A great day out and the organizers were superb. They got the right people in and wrong ones out very promptly. 😬 Val (Yellow/Black R400) Link to comment Share on other sites More sharing options...
bstark Posted March 29, 2009 Share Posted March 29, 2009 My old standard 4-2-1 rear exit on my x-flow was between 101-103dB depending who tested it... 😳 I swallowed hard and got a repackable Powerspeed side exit - MUCH quieter exhaust (94dB from memory), it spits flames better 😬 and the balance of sound is now massively torwards the (much more tuneful) twin 40's . If I'd known I would have changed over much sooner...   Bob Stark Supersprinter Link to comment Share on other sites More sharing options...
millsn Posted March 29, 2009 Share Posted March 29, 2009 I'd recommend Raceco too. Lovely piece of kit Link to comment Share on other sites More sharing options...
Bilbo Posted March 29, 2009 Share Posted March 29, 2009 Q102 Tap the silencer with say a hammer if it rings all the wadding is a gone if its a dull note most is still in place Even my car at 2/3 rpm that’s about 5600rpm can easily manage 105 dB(A) with a freshly packed Techcraft re-packable silencer     'Can you hear me running' ......... OH YES and its music to my ears 😬 😬 😬 1988 200 bhp, 146 ft lbs, 1700cc Cosworth BD? engineered by Roger King, on Weber's with Brooklands and Clamshell wings, Freestyle Motorsport suspension. Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted March 30, 2009 Share Posted March 30, 2009 RACECO. Just had my new one fitted by Mike. 99db at 0.5m, 45 deg - but to put it in persepective, even with a freshly packed techcraft can, I was struggling to get under 105db. ----- VDU 7X Pics More VDU 7X Pics Link to comment Share on other sites More sharing options...
ECR Posted March 30, 2009 Share Posted March 30, 2009 Alex  But... beware... on a different day with different environmental conditions readings can/will be different so you need a safety factor if trying to meet a published track limit. Link to comment Share on other sites More sharing options...
thesheep Posted August 18, 2009 Share Posted August 18, 2009 I'm also looking for a new silencer for my Xflow, which is now 20 years old. And the noise is just about unbearable at this point. I think my maximum budget for this is about £250... so Raceco looks like it's probably out of my league. Any other more budget suggestions? -------------------------------------------------------- Caterham7Junkie.com Link to comment Share on other sites More sharing options...
tbird Posted August 18, 2009 Share Posted August 18, 2009 thesheep , mabe talk to madhatter here they are doing a bulk buy at the moment Link to comment Share on other sites More sharing options...
MusCat Posted August 18, 2009 Share Posted August 18, 2009 My '89 xflow was between 104 and 106 with a standard CC can with 1in4 preliminaries.  Replaced it with a 6" repackable Powerspeed with a addional crushed cone of perforated pipe in the end of the perforated pipe - £340 back in 2005. I also have copper exhaust gaskets - it's now at 98.  I think induction noise is now the problem. Link to comment Share on other sites More sharing options...
Paul Kennedy Posted August 19, 2009 Share Posted August 19, 2009 Hi, I have a VX1600 8v with a standard 5 inch exhaust. I followed the lead of others on blatchat and converted the can to make it repackable. Searching the archive will give you loads of info if you are interested. I measured the noise last week at 105db (45 degrees, 50cms) and repacked it over the weekend with e glass, immediate reduction to 94db. The modification of the silencer cost about £50 in total, including s/s rivets and e glass. Probably took me 2 days effort and a lot of patience! Regards, Paul Link to comment Share on other sites More sharing options...
thesheep Posted August 19, 2009 Share Posted August 19, 2009 Ah ha, now that sounds like a budget option. Convert the one I have now. OK will do a search on it. -------------------------------------------------------- Caterham7Junkie.com Link to comment Share on other sites More sharing options...
Paul Kennedy Posted August 19, 2009 Share Posted August 19, 2009 From memory CC were selling the standard 5inch silencer for about £125 last summer. Maybe worth a call, would save a lot of effort, but not a long term solution. Paul Link to comment Share on other sites More sharing options...
Jason Plato Posted August 19, 2009 Share Posted August 19, 2009 as Paul says above - make your own repackable. Its not rocket science  I've donr several now and the duratec results are circa 94db at 4500rpm at 45 degrees. and K series are circa 97db at the same revs and position. here is my Duratec R .... C7 TOP Taffia joint AO with Al Link to comment Share on other sites More sharing options...
A Ashby Posted September 18, 2009 Share Posted September 18, 2009 RACECO titanium *thumbup* Look great, breath well and still do the quiet thing very well 😬 Link to comment Share on other sites More sharing options...
Racing Snake Posted September 19, 2009 Share Posted September 19, 2009 Speak to Mark (blat Meister) And join the bulk buy and get one made for your car at Good Fabrications Diplomatic Liason Officer For Penn 7's Mad Hatter Racing - Feel The Duralight R Torque 😬 Carl Van Baars Link to comment Share on other sites More sharing options...
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