Maney exhaust downpipe length (headers)
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Moto55UK
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I fully agree with steve a, Ring Nigel at NRP , take the outfit down to him , you wont be disapointed. Nigel's a great guy and his workshop is one of my favourite places to visit.Are you convinced you need a 2 into one? I run single pipes, I am biased, but I can show you a graph that says it's better in the mid range than a Maney system with a PW3 profile cam (JS2 is PW3ish)!
And I reckon mid range is what you need on an outfit? And don't say 'a 2 into 1 makes better mid range and single pipes make better top end' that is a popular myth which the comparison of my system and Maney's shows to be wrong on both points. Search some threads on here, it has been discussed, you might want to look for inputs from 'Snotzo'.
Anyway, Nigel at NRP made it. And he has made many more. Nortons well catered for, just tell him the cam you are using.
On the noise front, the Maney system has always been noted as 'noisy'. Single pipes have the benefit of two cans to help with that. Nigel is pretty close to the racers and knows all about meeting UK noise regs.
From my perspective, NRP is 'on your doorstep'!
A word on primary length for a 1 3/4" ID pipe, you will measure '73/'74 works Nortons as 28", I used that on my '75/'76 build 850, and it works fine, but.....you need Norman White to tell you that the pipe you could see was indeed 28" long, but a further 2" went inside the megaphone
I can tell you Nigel's pipes on my 750 short stroke are longer than 28", however there isn't a clear start point for a Mega as in the old days, the pipe gets bigger in steps until it gets to the silencer.
So there you go, you now have 'anything from 28" to 37"' Bet you are glad you asked!
SteveA
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If I was tasked to run a historic meeting, that is probably the first thing I would do too!
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I used 34" on my old BSA A70, as a 2 into 1. As I said earlier, I have considered NRP, but seeing as this is a stop gap chassis, I dont want to waste good money on a top exhaust system, only to have to make another one for the new chassis, in a year or so time.Have you ever tried packaging 2 exhausts on an outfit? Anyway thankyou, for being the first one to actually try to answer my question. Think I will just scale them of a picture.BTW, NRP is twice as far from me as Tony Laws.Are you convinced you need a 2 into one? I run single pipes, I am biased, but I can show you a graph that says it's better in the mid range than a Maney system with a PW3 profile cam (JS2 is PW3ish)!
And I reckon mid range is what you need on an outfit? And don't say 'a 2 into 1 makes better mid range and single pipes make better top end' that is a popular myth which the comparison of my system and Maney's shows to be wrong on both points. Search some threads on here, it has been discussed, you might want to look for inputs from 'Snotzo'.
Anyway, Nigel at NRP made it. And he has made many more. Nortons well catered for, just tell him the cam you are using.
On the noise front, the Maney system has always been noted as 'noisy'. Single pipes have the benefit of two cans to help with that. Nigel is pretty close to the racers and knows all about meeting UK noise regs.
From my perspective, NRP is 'on your doorstep'!
A word on primary length for a 1 3/4" ID pipe, you will measure '73/'74 works Nortons as 28", I used that on my '75/'76 build 850, and it works fine, but.....you need Norman White to tell you that the pipe you could see was indeed 28" long, but a further 2" went inside the megaphone
I can tell you Nigel's pipes on my 750 short stroke are longer than 28", however there isn't a clear start point for a Mega as in the old days, the pipe gets bigger in steps until it gets to the silencer.
So there you go, you now have 'anything from 28" to 37"' Bet you are glad you asked!
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As I said, I dont have money to burn, and as this is a stop gap chassis I dont want to waste money I havent got, only to have to have new pipes made again in a years time.
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Hi Tony , sorry for the delay ,but they were somewhere in the shed , finally found them , according to previous post I took different measurements (inside outside and so ) add them , and make the mean , they are both 85/84 cm , as said they are early Maney 's one so the left hander (visually it is evident, not so on the right hander ) is shorter which could explain why Brooking 's one are 92cm , hope this help , have a nice day.
SteveA
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Nigel is 400 miles and a 6 hour ferry crossing from me!
Actually, when he made my exhaust, the pricing was pretty good, certainly not the most expensive.
I don't know how radically you will change the outfit design, I had imagined reworking would be possible. And no, I haven't packaged exhausts on a sidecar, but plenty of the ones I have seen over the years use separate exhausts. I gave Nigel a little challenge on my Rickman.
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Thankyou that has answered my question exactly, much appreciated.
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When I built the chassis (being the first one I ever did), I cocked up on the front downtubes, and there are other areas of the design, I know I can do better. So it will be a completely different design of frame, making much more room for the exhaust downpipes, than the current one. Tony Laws is 67miles from me. NRP is Newark so 130. All I want at the moment is to finish what I have, and get it on the track. When I get round to doing a new centre frame, there will be a lot more thought put into the exhausts, I may take it to NRP, or possibly Raysons. But for now, that would be a waste of money.
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Correct, anyone thats ridden a non reed valve TZ700 will attest, smooth power delivery is completely uneccassary in an outfit.
SteveA
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Raysons, another good name, particularly for traditional methods.
SteveA
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There is interesting information.
But let's stick with inches, so say 33.5" (ish)
It comes to mind that Paul Dunstall used to recommend 32", and as said earlier I ran 28", I don't think I said but that was with a 4S like cam, ex Thruxton, that particular variety was a PW design!
But I know Brooking 850 dyno tested his, and it seems runs a longer 36" pipe.
The shorter pipes will have been designed to run with a 2S/3S/4S cam, all ballpark similar timing, which would seem to have different needs to a PW3.
I am fairly sure of this because I ran two cams that were 2S based with an exhaust designed for a PW3 cam. Both of those cams would have needed exhaust changes to gain the best performance.
But instead I have gone back to a PW3 profile and the set up works better, it revs higher and more freely, I feel it punches better out of corners. Overall, it suits me much better.
I think this is a trend and with modern silencers and 'mega' designs, the longer pipe seems to be more appropriate, particularly with a PW3 profile, which most of us are using.
Anyway, always better to start longer and cut it down if needed!
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Thanks usefull information.Punch off corners is what I will be looking for.
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With a 2 into 1 exhaust, there is a very long system which must be made to resonate, so you need a stronger pulse from the exhaust port. Extra advance on the inlet valve opening point also helps. My cam sprocket has two extra keyways broached into it at random positions. Because my bike is only raced, I did not even bother to re-harden the sprocket.
