Alex Wong1697456877 Posted March 6, 2001 Share Posted March 6, 2001 I ask this question with my cheque book locked away.... blush.gif How critical is the exhaust system? Perhaps more accurately asked, how inadequate (if indeed it is at all) is the Caterham 4:1 Vx competition exhaust and does anybody have any experience of the SBD setup? P.S. If Roger S is reading this, I can see you smirking from here!!!! smile.gif Alex Edited by - Alex Wong on 6 Mar 2001 11:14:09 Link to comment Share on other sites More sharing options...
Mike Bees Posted March 6, 2001 Share Posted March 6, 2001 It depends what you mean by 'critical'. A well-specified 4-2-1 will give you more mid-range than a 4-1 at little or no cost to the top end. I'm still using the standard Caterham 4-1 competition exhaust on my 230+bhp K-series, but a recent day on the rollers playing with various pipe lengths & configurations showed that almost any 4-2-1 configuration would beat it by up to 15lbft in the mid-range with an almost insignificantly small loss at the top end. The main problem on a Caterham is finding room for enough primary & secondary length and still being able to get a reasonable length silencer in. Arnie's bonnet-exiting setup appears to do this, although I don't know how it would get on at increasingly noise-sensitive venues? Mike Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted March 6, 2001 Author Share Posted March 6, 2001 Thanks Mike I guess it is optimal to dyno the engine with the exhaust that I'm going to use. If I have it dyno'd with the 4:1 exhaust, would I have to re-dyno it with the 4:2:1 to see the benefit? Alex Link to comment Share on other sites More sharing options...
EFA Posted March 6, 2001 Share Posted March 6, 2001 I agree with Mike on this. Noise levels on my car seem to be induction. Static levels are OK, Driveby's are horrendous if the microphone is on the inlet side of the car. Arnie Webb The Fat Bloke blush.gif in a Slow Old Vauxhall wink.gif Link to comment Share on other sites More sharing options...
Mike Bees Posted March 6, 2001 Share Posted March 6, 2001 Alex - to get the best out of it you'd want to get the map tweaked to suit the exhaust. We found some (but not all) 4-2-1 configurations where with the 4-1 map the engine wouldn't take full throttle, although these were unusual configurations. The relatively standard 4-2-1 we tried ran fine and really smoothed out the torque curve nicely compared to the 4-1, but I'm sure it would still have benefitted from some map-tweaking to optimise for it. Mike Link to comment Share on other sites More sharing options...
Peter Carmichael Posted March 6, 2001 Share Posted March 6, 2001 Mike, I would be amazed if fuelling didn't make huge differences with the different exhausts. BTW, your fuelling at the top end looked really suspect when I took over your map (still going up when the torque was dropping). Any chance of sending me any of the graphs/results? Link to comment Share on other sites More sharing options...
StewartG Posted March 6, 2001 Share Posted March 6, 2001 Alex, why don't you get a Fast Arnie type manifold you know you want to, and you could keep the take away warm without having to take the bonnet off. Link to comment Share on other sites More sharing options...
EFA Posted March 7, 2001 Share Posted March 7, 2001 Great for bacon sarnies as well. Many breakfasts have been served from my manifold over the years.... Fried eggs are a little more difficult. Just have to remember to put the Mazola on the exhaust and the SynerG in the dry sump tank..... Arnie Webb The Fat Bloke blush.gif in a Slow Old Vauxhall wink.gif Link to comment Share on other sites More sharing options...
Nick Pargiter Posted March 7, 2001 Share Posted March 7, 2001 Alex, Have got SBD( BTB Exhausts )set up with primary pipes exiting in standard position. The primary pipes do all fit in under the bonnet. Noise doesn't appear to be problem, have been told it is quiet enough for Goodwood where the required levels are low. Only notice the noise when the loud pedal is buried in the carpet! Link to comment Share on other sites More sharing options...
Mike Bees Posted March 7, 2001 Share Posted March 7, 2001 Nick - I'd get it tested before you go to Goodwood. A fellow competitor has an SBD 1.6 K-series with their manifold and carbon can, he turned up for a sprint and Goodwood and was sent home after one practice lap. Failed the static test but they let him practice anyway and then sent him away. Much noisier than my standard Caterham 5" job. Mike Link to comment Share on other sites More sharing options...
Andrew Russell Posted March 7, 2001 Share Posted March 7, 2001 Mike, So you still use the Caterham 5" silencer for your car and it is adequate? Is the 6" box likely to give any significant sound deadening improvement over the 5" ? The silencer on my Vx XE, about 200 bhp, is the 5" item, but has had a hard life and the contents have,I fear, burnt out. Time for a replacement.... Having looked at the options, I feel that the Caterham unit is probably the best choice, but what size to go for? I presume that the boxes are all universal fit on the Caterham side exit 'race' manifolds? Sorry for hijacking Alex's thread, but I suppose the is some link! Any comments please, anyone? Andrew. Edited by - Andrew Russell on 7 Mar 2001 08:52:22 Link to comment Share on other sites More sharing options...
Mike Bees Posted March 7, 2001 Share Posted March 7, 2001 Andrew - I used the 5" box in '98 and '99 and it was adequate. It probably isn't any more. I've got a 6" repackable aluminium can now which is considerably quieter. I don't know if the 5" & 6" Caterham cans are the same pattern fit - the 6" ones I've seen on the SLRs only fit with the 4-2-1 manifold, but best to check with them as to what they really have to offer. Mike Link to comment Share on other sites More sharing options...
I reply to every thread Posted March 7, 2001 Share Posted March 7, 2001 Raceline used to (may still) do a 7" which seemed very quiet. Mind you that was on a Zetec with standard cams. I've got a feeling that it was tested at 5500 RPM static and was about 95db. Looked good too. Link to comment Share on other sites More sharing options...
Alex Wong1697456877 Posted March 7, 2001 Author Share Posted March 7, 2001 Nick, Did you notice any change with the SBD setup and did it require any mapping changes? Cheers, Alex Link to comment Share on other sites More sharing options...
Graham Perry Posted March 8, 2001 Share Posted March 8, 2001 Mike, After all the chopping and changing on the rollers did you decide to change your manifold in the end ? If so, was it one off the shelf or a bespoke unit ? Link to comment Share on other sites More sharing options...
Mike Bees Posted March 8, 2001 Share Posted March 8, 2001 I had borrowed a new 4-2-1 setup from Mick Smith, which was the winner on the day. Can't afford to get one of those made up at the moment. I also got some cheapy 2-1 collectors made up to convert my existing manifold into a 4-2-1 (using the existing primaries) for the purposes of the experiment. To stick it on the car I'd need a shorter exhaust can. I'll be sticking with the 4-1 until such time as I can afford to do otherwise. Mike Link to comment Share on other sites More sharing options...
Graham Perry Posted March 8, 2001 Share Posted March 8, 2001 I was thinking that there seems to be a lot of heresay, pubtalk and general misinformation on performance of various exhaust manifolds for the K and I guess it would be good for all users if some real data was posted on this subject. Of course there is always room for improvement but a 15lb improvement in torque sounds fantastic for a 1700. I bet there are many subscribers that could benefit if the general dimensions of the various manifolds and performance comparisons were available. Sounds like Mikes day was worthwhile. Link to comment Share on other sites More sharing options...
Nick Pargiter Posted March 8, 2001 Share Posted March 8, 2001 Alex The exhaust ran for a bit with the standard injection(Vauxhall 2L engine by the way) and there was a difference in mid to high end performance. This was comparred to the Caterham 4-1 system previously fitted. This was emphasised more when we fitted the throttle-body kit. As for noise the SPD set-up is quieter than Caterham's but that is only speaking from the passenger seat. Nick Edited by - Nick Pargiter on 8 Mar 2001 11:59:30 Link to comment Share on other sites More sharing options...
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