ChrisC Posted November 10, 2003 Share Posted November 10, 2003 Hi All I did not have a good day at Bedford this Saturday. For the first time I was back flagged for noise. The day started ok with a 94db static test, but the drive by was tipping the scale at 90db. Bedford I know has low limits (87 db), but this was my third time there this year with the same car, and the first time I had a problem, so what has caused the extra noise? Things that have changed from last time. 1, The exhaust was repacked. static was 99db and 100db previously. So I would have thought this was helping. 2, An ECU changed to include a 3D map over the original 2D. 3, The much colder weather. The is a standard ish VX XE (if there is such a thing) on carbs, with a Raceco exhaust and MBE 967 ecu (changed cos the old on went pop) Would fitting Pipercross filter socks inside my K & N’s going to help? all advise gratefully received.. PS never go to track days associated with Redline/Max Power style mags. Chris.... H15 SVN Get it ! Link to comment Share on other sites More sharing options...
Harry Flatters Posted November 10, 2003 Share Posted November 10, 2003 Fitting socks can result in power loss and I doubt if it would help the noise problem. The only sure way to reduce induction noise would be to fit an airbox. *arrowright*Harry Flatters *arrowright* AKA Steve Mell of Su77on Se7ens and Surrey Joint AO Link to comment Share on other sites More sharing options...
Peter Carmichael Posted November 10, 2003 Share Posted November 10, 2003 Tyre noise is a significant contributory factor to drive by. Have you made any changes to tyres? Link to comment Share on other sites More sharing options...
ChrisC Posted November 10, 2003 Author Share Posted November 10, 2003 Harry - you know the rules (not mine) K & N's must stay. Peter - I was using a new set of ACB10's after finishing the last set off last time 😬 Tyre presser was also altered from 20 psi to 18 all round this time. Chris.... H15 SVN Get it ! Link to comment Share on other sites More sharing options...
Tony Martyr Posted November 10, 2003 Share Posted November 10, 2003 New ACB 10s would give a very distinctive noise that is dominated by the tyre slot passing frquency. You must be able to recognise the charatoristic sound which may be in the high sensitivity band of 'A' weighing. Cold weather would have produced more engine power which increases the noise output. If the previous sensing had been done with a helpful wind you may have been under rated. Link to comment Share on other sites More sharing options...
ChrisC Posted November 10, 2003 Author Share Posted November 10, 2003 It looks like its time to try a little testing. Does anyone know a good place to buy a Noise Meter? I have seen the same meter advertised in DT at Maplin Electronic for £55. I know that I can't take a reading from such a meter and assume I am going to be ok on a track day, but I will be able to do back to back test to see if I can reduce the drive by noise. i.e. Drive By the meter, then reduce the tyre pressures (or whatever) and Drive By again. It might be nice to have a box of tricks up my sleeve to reduce the noise and keep on the track. Better than making my way home after only a few laps (not what happened Saturday got kicked off at 3.00 pm) but there was a Atom there that was on the trailer home well before lunch. If fact the Redline day was very frustrating, each time I went out, I just got the car/tyres warm and then a Red Flag would close the track. I have never seen so many accidents, and I feel sorry for the young man how bounced his Clio 172 from nose to boot, and landed it on the roof after what looked like an innocent spin right in front of the pits. Lets hope he has track insurance. Chris.... H15 SVN Get it ! Link to comment Share on other sites More sharing options...
stevefoster Posted November 10, 2003 Share Posted November 10, 2003 How silly all this is. Off to sulk.... My racing info site here Hants (North) and Berkshire Area club site here Light blocks here Edited by - stevefoster on 10 Nov 2003 21:49:37 Link to comment Share on other sites More sharing options...
m bedard Posted November 10, 2003 Share Posted November 10, 2003 I've read that longer trumpets on 45 webers can have a significant affect on performance. My Caterham has a potent(225 h.p.) engine with K&N filters. If I went with longer trumpets I would have to switch to something like pipercross foam socks, any thoughts? Link to comment Share on other sites More sharing options...
Bangers quotNquot Mas1697456953 Posted November 10, 2003 Share Posted November 10, 2003 Bedford I know has low limits (87 db), WHY?????? This is the ex RAE aircraft test and development site. They made more noise here over the past 40 or so years than every unsilenced Caterham running at full t.t could ever produce!!! (in unison!!) It's a bl..dy racetrack for christ sake!! They'll be checking emissions next!! 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 Link to comment Share on other sites More sharing options...
thinfourth Posted November 10, 2003 Share Posted November 10, 2003 Well look on the bright side when this reachs its logical conclusion. Caterhams will be far faster round the track then any ferrari if only for the fact they weigh far less for when you are pushing them round the track and the roll bar will make a good hand hold for the nasty uphill sections. Bunch of 🙆🏻 Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted November 11, 2003 Share Posted November 11, 2003 If I went with longer trumpets I would have to switch to something like pipercross foam socks, any thoughts? I'd go for an ITG air filter or if you really don't want to modify the bonnet, I believe RamAir make a very good filter that will fit. I'm not sure longer trumpets would make much of a difference. Maybe a bit more top end and a bit less mid range, but we're talking tiny margins here. FWIW, my setup has very short stubby trumpets and works pretty well. A bit unscientific I know.... My car struggled to pass 105dB driveby at Brands with the meter facing the exhaust side (which since then, has been changed to a Raceco silencer - no more probs at brands now!), but was fine for a 98dB driveby at Donnington with the meter facing the inlet. Strange... Edited by - Alex Wong on 11 Nov 2003 00:24:00 Link to comment Share on other sites More sharing options...
Bare Posted November 11, 2003 Share Posted November 11, 2003 I'd Say the Much colder weather.. Known fact that Aero engines produce significantly higher DB's when Air temps are low ... even more so when below Freezing. Personally I take issue with owners who persist in having Ridiculously loud exhausts on their Toy cars, simply cuz they are so selfish that they think it's their Gawd Given Right to be as loud as they deem necessary using the pretense of generating the last Erg of power. Or mebe they just have some "Lookit Meeee" disorder. If this was a 'regular' car, the general public, not to mention the Constabulary, would be openly aggressive about the noise levels Today's Rant :-). Link to comment Share on other sites More sharing options...
Bangers quotNquot Mas1697456953 Posted November 11, 2003 Share Posted November 11, 2003 "the Constabulary, would be openly aggressive about the noise levels" What, they'd chase you with their ridiculous "Dukes of Hazard" siren's wailing *confused* Link to comment Share on other sites More sharing options...
Bob_r Posted November 11, 2003 Share Posted November 11, 2003 owners who persist in having Ridiculously loud exhausts on their Toy cars put your claws away, my car has a standard fit Caterham box and can't meet the requirements at Bedford unles I short shift past all 7 meters, Caterham in their wisdom can fit a bigger exhaust and carbon air box quiet kit if I want it, at a combined cost of approx £1,500.00, seems to me that they are creating profit opportunities ! Still - you pays your money as they say! Link to comment Share on other sites More sharing options...
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