Dazza Posted September 27, 2001 Share Posted September 27, 2001 I have owned a '94 JPE for about 4 months now and am still amazed at how LOUD it is. I was recently black-flagged at a track day for being too loud. They clocked me at 96dB (the track limit was 95dB!). Does anyone have any experience with quietening the exhaust note while still keeping the existing original muffler. Can more baffling be fitted without cutting it apart? I would like to try to keep all the JPE parts as original as possible. Link to comment Share on other sites More sharing options...
Drumster Posted September 27, 2001 Share Posted September 27, 2001 Suggestion: Go to track days that have a higher noise limit? Its easier than playing around with the noise levels smile.gif Chris Alston Se7ening - it's all miles and smile.gifsmile.gifsmile.gif 1800 Supersprint - Loud and Proud teeth.gif Edited by - C7CAT on 27 Sep 2001 12:49:32 Link to comment Share on other sites More sharing options...
V7 SLR Posted September 27, 2001 Share Posted September 27, 2001 96dB..? Blimey, where was this? A bit draconian. I agree with Chris, find track days that allow louder limits. Most do. That must be the lowest I've ever seen (cue: loads of "Well, it was XdB at the last track day I went to" replies). Link to comment Share on other sites More sharing options...
Nick M Posted September 27, 2001 Share Posted September 27, 2001 I'm assuming it's 95db drive-by, which are often lower than static tests. Was that the case ? And which track was it out of curiosity ? Link to comment Share on other sites More sharing options...
Jason Plato Posted September 27, 2001 Share Posted September 27, 2001 You should bear in mind that much of your drive by noise will be due to the air induction as well as the exhaust . What was your static noise reading ? . You may have to consider silencing the engine at both ends !! as on the R500 and many other throttle boddied cars with the intake sticking out of the bonnet sad.gif Dave Link to comment Share on other sites More sharing options...
Darryl S. Posted September 27, 2001 Share Posted September 27, 2001 Darren, I've never heard of them actually enforcing any noise limits here? Was it a bike/car day at Eastern Creek? I know with the sprints Dave and I are doing while they give a maximum noise limit, there actually is no sampling. Link to comment Share on other sites More sharing options...
Dazza Posted September 28, 2001 Author Share Posted September 28, 2001 Thanks for all the replies guys. Yes, Darryl is right, it was at a commercially organised Car/Bike tack day during the week at Eastern Creek here in Sydney, Australia. The sensors are located at 300m before turn one, about half way down pit straight. I have not had any static other type of noise measurement done on the car, so cannot comment. Certainly a large amount of the noise is induction related. At the time I was at around 7500rpm and the speedo was reading 145mph (which since it is so inaccurate, it was probably more like 120mph.... just one more thing to get looked at!). In any case, they were fine about it and I just promised to not rev it so much at that point on the track. I was just hoping that there was an easy, quick and cheap (is there ever such a thing?) fix to reduce the noise slightly which leaving the power untouched. It would certainly help when driving on the road. Once again, thanks for your comments. Link to comment Share on other sites More sharing options...
Darryl S. Posted September 28, 2001 Share Posted September 28, 2001 Maybe a slightly longer muffler may help. Shouldn't be a big cost item, I see no reason why you couldn't get the JPE heatshield fitted so it still looks like the standard can is fitted. So how were you looking at the speedo 300m before turn one Darren?? I've found your normally getting tightening of the sphincter at that spot seeing as your going to take the corner flat out eek.gif` Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted September 28, 2001 Share Posted September 28, 2001 96dB? My car (QED Vx) clocked 104dB drive by at Brands. I'm still trying to think of ways to make it quieter. Alex Link to comment Share on other sites More sharing options...
EFA Posted September 29, 2001 Share Posted September 29, 2001 I managed 116db static when Nigel tested my car at Stoneleigh! The Std JPE silencer is only 5" - I had the JJPE system on my car from new. Big reduction in noise can be gained by fitting a larger diameter can. In Aus, the problem you have is obtaining one and getting the necessary mods carried out. I would suggest geting a JPE collector and R500 track can (the 7" one) fabricated together - this wasy you can keep your std silencer (off the car) and utilise the existing headers without modification. best option however would be a larger bore system with equal length primaries and a 4-2-1 configuration. This would get you close to the 250bhp the Swindon engine can produce in a more ideal installation. As fitted to the JPE they put out little more than 210bhp in a truly unusable manner! Fat Arn The NOW PROVEN R500 Eaterid=red> See the Lotus Seven Club 4 Counties Area Website hereid=green> Link to comment Share on other sites More sharing options...
Dazza Posted September 29, 2001 Author Share Posted September 29, 2001 Thanks for the ideas everyone. Arnie, I'm incredibly impressed with your K2RUM. It would seem to be the ultimate manifestation of extracting every last performance improvement out of the Lotus 7 concept! I was very interested in the exhaust layout you have installed. Especially the 4-2-1 format. What is the reason for the high angle of the header pipes? Obviously the JPE has the 4 header pipes collected into 1 directly. I notice in the Parts Catalogue there is a 4-2-1 collector. Do you think there would be a noticeable improvement just fitting this part instead of the current 4-1 collector (in power)? Obviously a fully custom system like yours would be ideal. Arnie, Can you just explain once more for the dummies what to do with the R500 part. Start from the end of the collector (just past where the Lambda probe is)..... how exactly are you suggesting my standard silencer is to be fitted together with the R500 part? Thanks Very interested in your comments on the power output of my engine as fitted standard to the JPE. With my other car being a Volvo (literally!), the power on tap is so phenomenal that I never stopped to think that it wasn't the claimed 250bhp. I haven't had it dynoed yet as I am still in the phase of sorting out some other basic problems (just replaced fuel pump etc), rather than trying to increase performance above standard. Will talk to your further on this in due course. Thanks Link to comment Share on other sites More sharing options...
Dazza Posted September 29, 2001 Author Share Posted September 29, 2001 Hey Darryl, Good point about Turn 1 at Eastern Creek. I have heard it referred to as Slazengers (...you need big ones to take it flat out). I really need to get my speedo accurate as the car seems to handle the corner as fast as I am game to take it. I think the diffuser fitted to the rear helps. I am keen to get out there again to check out what improvement my recent wheel alignment has made. cheers Link to comment Share on other sites More sharing options...
EFA Posted September 30, 2001 Share Posted September 30, 2001 Dazza, Here's the answers - Straighter headers improve extraction flow which gives more power. The length of specific exhaust sections will also effect where the torque is delivered and how progressive the torge delivery is. A 4-2-1 system enhances this effect at the low end. The 4-2-1 in the Caterham brochure I think is only for K Series engines, not VX On the JPE the collector and silencer are 1 piece, so you would need to buy or have copied the collector section and have an R500 track silencer grafted on the rear by a local SS expert. These things are absolutely tacked up on the car to ensure everything fits correctly. If you could get your car to the UK you would be able to get a complete system made up and store the original JPE bits. The Swindon Racing Engines dyno sheet for your engine would without doubt have shown the 248bhp Swindon claim, but when Caterham fitted the engines to the JPE they used an angled inlet manifold (to rplicate the Weber position) and an imbalanced exhaust system. Result was a 30+ bhp loss. The same was true of the 235bhp carb VX "235 evolution" engine which came in my car when new - this, when dynoed only gave 197bhp, and when re-jetted we could not get it above 206 bhp. WHat did you use as a replacement fuel pump?? The JPE (and my car) use a Rover 820 Turbo pump grafted to a 1.4k pump mounting. This can deliver about 80psi max pressure, although the regulator reduces this to 40 -60 psi in most cars. Fat Arn The NOW PROVEN R500 Eaterid=red> See the Lotus Seven Club 4 Counties Area Website hereid=green> Link to comment Share on other sites More sharing options...
Dazza Posted October 1, 2001 Author Share Posted October 1, 2001 Thanks for the explanation Arnie. Will pursue getting the R500 silencer sent out from Caterham and getting the rest of the system fabricated here to give the 4-2-1 system. Also, I shall start trying to find out who has the skills and experience locally to build a full optimised system similar to yours. It is amazing the effect of the kink has in the inlet manifold and the exhaust manifold. I guess the theory was that to keep the traditional profile of the car and not have the induction trumpets and the exhaust sticking out of the bonnet vertically, concessions to power were made. You have obviously demonstrated what can be done and I'm looking forward to exploring some of those areas as time and money allow. With regards the fuel pump.... we found that the fuel pressure was fine (around 38psi regulated), but that the fuel flow rate was horrible when the fuel pump got hot (30-60minutes). We was the flow at 1.2 litres/min and dropping fast. Taking the fuel pump out showed that the filter bag was blocked and as it has no "frame" to keep its shape, it had collapsed and the pump was trying to suck fuel thru 1 square cm! We could have ordered an identical part locally (believe it is a Rover unit), but would have cost over A$600. We installed a GMH Commodore pump (locally available and A$150) and it is rock steady at 2.2 l/min even at max revs. Link to comment Share on other sites More sharing options...
Slipper man Posted October 1, 2001 Share Posted October 1, 2001 Don't listen to Arnie - you'll ruin the car if you optimise the exhaust. The JPE is faster than anything else you will ever come across as it is, so why try to make it faster. If you just get Caterham to build you a collector to fit the JPE manifold, plus a 7" race silencer (or Techcraft unit), then you can leave the standard exhaust in place for road use, and change silencers if you are going on the track (takes less than 10 minutes). Then your pristine JPE will still look lovely. Oh yes, and don't think about painting it puke yellow either wink.gif Link to comment Share on other sites More sharing options...
EFA Posted October 1, 2001 Share Posted October 1, 2001 No, paint it a much brighter shade of yellow thumbsup.gifPuke yellow is rather dull.... Go do some work Jex! Fat Arn The NOW PROVEN R500 Eaterid=red> See the Lotus Seven Club 4 Counties Area Website hereid=green> Link to comment Share on other sites More sharing options...
Spartacus Posted October 1, 2001 Share Posted October 1, 2001 Oh exulted one. Where have you been? Hail Slipperman smile.gif I AM SPARTACUSmad.gif Link to comment Share on other sites More sharing options...
Dazza Posted October 2, 2001 Author Share Posted October 2, 2001 I can see you guys have a lot of fun over there in the UK with your se7ens and that some healthy rivalry is alive and well. I like your idea Keith and if I get a silencer from Caterham I am sure I have a suitable collector made here in Oz. Too late on the puke yellow. The previous owner painted the Dymag wheels that lovely colour along with a stripe down the bonnet. It does look rather good, but I can't imagine what a whole car of that colour looks like in the flesh. cheers darren Link to comment Share on other sites More sharing options...
EFA Posted October 2, 2001 Share Posted October 2, 2001 Darren, Puke Yellow is a Lada shade, rather like Keiths dull R500....... Your wheels and stripe are a fabulous colour. Excellent taste.... Fat Arn The NOW PROVEN R500 Eaterid=red> See the Lotus Seven Club 4 Counties Area Website hereid=green> Edited by - Fat Arnie on 2 Oct 2001 13:52:48 Link to comment Share on other sites More sharing options...
EFA Posted October 2, 2001 Share Posted October 2, 2001 Oh and regrading Keiths "go to Caterham idea" you can save skip the middle man by going to Cheesmans direct, although their work is pretty awful. I'd settle for a local fabricator. Fat Arn The NOW PROVEN R500 Eaterid=red> See the Lotus Seven Club 4 Counties Area Website hereid=green> Link to comment Share on other sites More sharing options...
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