Nemesis Posted June 23, 2004 Share Posted June 23, 2004 errrr see the subject title! Link to comment Share on other sites More sharing options...
Peter Carmichael Posted June 23, 2004 Share Posted June 23, 2004 Nemesis, You are supposed to put the engine in the middle, not join them directly one to the other. Link to comment Share on other sites More sharing options...
david nelson Posted June 23, 2004 Share Posted June 23, 2004 😬 😬 😬 😬 😬 😬 😬 Link to comment Share on other sites More sharing options...
Paulo Posted June 23, 2004 Share Posted June 23, 2004 Dartford Link to comment Share on other sites More sharing options...
Christian P Posted June 23, 2004 Share Posted June 23, 2004 Nemesis, Lots of previous threads on 4-2-1 systems so worth a search. Not being technically savvy I wouldn't know definitively whether you need to match exhaust specifically to the inlet system; instead, I thought it was exhaust (primaries' length, specifically) to engine. At least, that's what I understood when getting a Powerspeed system for my 1.6K. Anyway, there we are. C7 CCL - broom broom Link to comment Share on other sites More sharing options...
Nemesis Posted June 23, 2004 Author Share Posted June 23, 2004 you know tech talk isn't all its cracked up to you know! I reckon I have a reputation ! 😳 Nemesis Click here ARE YOU STUUPIDD I EM THE LAWE, I EM IN CHERGE ERE Link to comment Share on other sites More sharing options...
V7 SLR Posted June 23, 2004 Share Posted June 23, 2004 There's no benefit in a 4-2-1 on a 1.6, whereas the 1.8 definitely shows an improvement at around 4000rpm. Nemesis, whilst I don't think much of the can, the standard SLR manifold and 4-2-1 is OK. Number 4 manifold wraps around the starter a bit close for comfort and definitely contributes to the K series starter-o'-doom, but from a power perspective, it works pretty well. Then again, it's not cheap and I suspect you can get a similarly designed one from elsewhere for the same price, and one which addresses the No 4 problem. Link to comment Share on other sites More sharing options...
Christian P Posted June 23, 2004 Share Posted June 23, 2004 Perhaps I should have said that the engine has subsequently been DVA'd (gas-flowed head with larger inlet valves, hotter cams, verniers). Anyway, seems to go well and sounds nice too. (Sorry - slight thread hijack. Leaving now...) Link to comment Share on other sites More sharing options...
V7 SLR Posted June 23, 2004 Share Posted June 23, 2004 Doesn't really matter whether it's been DVA'd or not does it? Thought the 4-2-1 was very specific to engine size, rather than state of tune. Wonder what Dave Jackson uses. He must have the most powerful 1.6. Anyway, don't think a 4-2-1 can actually harm a 1.6 although there is some belief that the flattening of the torque curve at around 4000rpm is at the expense of a little top end power. If the 1.6 doesn't need the 4-2-1 it would make sense to stick with the 4-1 if that's true. Just some thoughts... Link to comment Share on other sites More sharing options...
martinwhitcher Posted June 24, 2004 Share Posted June 24, 2004 I have a 1.6K and changing to a 4-2-1 did make a great difference!in the mid-range Martin MW 51 CAT Superlight No.171 Link to comment Share on other sites More sharing options...
Jason Plato Posted June 24, 2004 Share Posted June 24, 2004 I had a caterham 4-1 comp manifold and when I changed to Caterham 4-2-1 manifold ( with a self built / modified r500 silencer ) there was improvements in the midrange on my little 1600 K, but this was done with a number of other minor mods , like a new head , inlet length etc etc etc so I cant actually say if any improvements were down to just the mainifold . I would expect the 4-2-1 to pick up the midrange on a std 1600 K . V7 , Caterham now produce a new design of SLR manifold , this has different headers on cylinders 3&4 to allow greater clearance for the new startermotors . The manifold also now has a improved exit angle from the head . Nem - I would go for the Caterham 4-2-1 SLR manifold and 6 " silencer with a cat replacement pipe . I have yet to see a nice powerspeed system . Dave Link to comment Share on other sites More sharing options...
Mark Durrant Posted June 24, 2004 Share Posted June 24, 2004 Nemesis I have the new Caterham 4-2-1 mated to a 6" Raceco can on my 1.8K Supersport. I can confirm that the primaries on 3 & 4 have been modded as stated by Dave and there is certainly a noticeable, but not measured improvement in mid-range torque. Pop along to the next Su77on Se7ens meet if you want to take a look. Mark D Su77on Se7ens Edited by - Mark Durrant on 24 Jun 2004 09:10:44 Link to comment Share on other sites More sharing options...
Pelico Posted June 24, 2004 Share Posted June 24, 2004 Oilyhands suggested that a 4-2-1 would even benefit my humble 1.4SS, and is a nice bit of groundwork for a future 1.8 converstion. So I to would be interested in any advice too. My Caterham owner's site Link to comment Share on other sites More sharing options...
Jason Plato Posted June 24, 2004 Share Posted June 24, 2004 Dont forget to adjust the timing on the std K to compliment the new zorst Link to comment Share on other sites More sharing options...
charlie_pank Posted June 24, 2004 Share Posted June 24, 2004 Nemesis. I would recommend Hayward & Scott here. I used them for my 4-2-1 on my 1.6 and there was a very noticeable improvement. You may want to get some more info about what length the primaries and secondaries should be. H&S workmanship is fantastic. - I think they may have had a hand in K2RUM at some point as it was on Arnie's recommendation that I went there originally. Hope this helps.... Link to comment Share on other sites More sharing options...
I reply to every thread Posted June 24, 2004 Share Posted June 24, 2004 2nd H&S for quality Link to comment Share on other sites More sharing options...
Peter Carmichael Posted June 24, 2004 Share Posted June 24, 2004 You should probably be careful of the people on this thread who are reporting an improvement of a 4-2-1 over the standard rubbish 4-1 within the engine bay. The competition 4-1 from Caterham shows a marked improvement in itself. The difference between a comp 4-1 and a 4-2-1 is less well researched. DaveJ has it about right that a bunch of things picked up the mid-range on his engine, in which the exhaust might well have been a contribution. Conventional wisdom suggests the 4-2-1 should pick up the midrange. There was an early back to back test (at Emerald I believe) that suggested that while this was true for the 1.8 it did nothing for a tuned 1.6. Having played around a bit in this area, I cannot suggest that there are hard and fast rules for ALL 1.6s vs. ALL 1.8s. My big engine ran on a 4-1. The interplay between exhaust length and trumpet length on the inlet side is interesting and the two need to be considered together. Nemesis, you are looking at a match for the roller barrels which sets the inlet length. The cam duration and timing is the other thing that has a significant effect on the pulse tuning. Generally, if the sum of the primary and secondary length is longer, there will be a push upwards in the torque lower in the rev range. The push from the primaries kicks in a bit higher up. This is also true of the inlet tract. Usually you can see this if you experiment with different lengths, with the resonances obviously moving up and down the rev range. If resonances on both inlet and exhaust are coincident, you may get a very high peak torque and a very narrow rev band. If you spread everything out so that complementary effects take over throughout the rev range then you can get an extended rev range which is what most people are after. I've seen a bunch of graphs suggesting a 33in set of primaries on a 4-1 gives a good result for mid-range. This overall length isn't a bad target for the total length of primaries and secondaries in a 4-2-1. My 4-1 is closer to 29in. Somewhere around 24in primaries and 10in secondaries might fit and do the job. Hayward and Scott, BTB(big money), EBD etc. can all match a manifold to a can of your choice. I believe Raceco are also now speccing, if not manufacturing manifolds. Alternatively a Caterham standard setup will fit and work, with the option to upgrade to a repackable can. Link to comment Share on other sites More sharing options...
AMMO Posted June 24, 2004 Share Posted June 24, 2004 The rule of thumb is that shorter headers are required for longer duration cams and higher rpm. As Peter rightly points out, the exhaust length is very much dependant on the induction length and cams. As the cam duration increases the tuned length of the primary becomes more critical. With road cams you can afford to be a bit vague. As my car is mainly for the road I went for 32" primaries (always a good starting point) with an experimental collector which I have specced. Its a kind of ersatz 4-2-1 that looks like a 4-1. Curious to see how ell it works. There is room on my system to shorten the headers if I feel this is neccessary. I had a 4 into 1 on my 187 bhp 1800cc Zetec and it never lacked performance. If it did lack mid-range torque I never noticed. In fact a lack of torque can be a good thing as you can nail the gas coming out of corners without the back end breaking away. Too much torque sometimes loses you time and probably requires a better driver than me! AMMO Link to comment Share on other sites More sharing options...
V7 SLR Posted June 24, 2004 Share Posted June 24, 2004 Interesting about the new SLR manifolds Dave. Cheers. Link to comment Share on other sites More sharing options...
Nemesis Posted June 24, 2004 Author Share Posted June 24, 2004 Dave and Mark And Mark do you guys promise not to disappear when I turn up next time 😳 Nemesis Click here ARE YOU STUUPIDD I EM THE LAWE, I EM IN CHERGE ERE Link to comment Share on other sites More sharing options...
Mark Durrant Posted June 25, 2004 Share Posted June 25, 2004 I'll try but I cannot promise for how long Mark D Su77on Se7ens Link to comment Share on other sites More sharing options...
Jason Plato Posted June 25, 2004 Share Posted June 25, 2004 I will always disappear if I see you coming edited to remove the swear words Edited by - Dave Jackson on 25 Jun 2004 08:30:40 Link to comment Share on other sites More sharing options...
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