ned
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| posted on 2/2/06 at 10:05 PM |
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I've been researching this (again!) lately for the design of my exhaust system that I'm having made in about a month's time.
I came across this thread on blatchat which might be of interest, as it mentions both lengths and diameters of high power vauxhall caterhams
exhausts..
http://www.blatchat.com/T.asp?id=4016
When they say primaries do they mean the total length of 4-2-1 and the secondary as the 2-1 bit? 30 odd inches sounds a lot to me otherwise, ut i do
have some pics I can post up to show examples of race spec bonnet exit 7 type exhausts which is essentially what I hope mine will turn out like..
Ned.
[Edited on 2/2/06 by ned]
beware, I've got yellow skin
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NS Dev
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| posted on 2/2/06 at 10:55 PM |
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The primary length on a 4-2-1 (as far as I know!!) refers to the combined 4-2 bit, not the entire 4-2-1.
If you measure a few long 4-2-1 systems from the valve to the 2-1 collector they should be around 30 inches. If you think rouchly 2'6" and
look at a few this is around the length they all run.
Worked on my grasser, improved torque a lot from the std vauxhall tubular 4-2-1, which is too short.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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ned
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| posted on 2/2/06 at 11:07 PM |
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ok its late and i'm being stupid, to quote the caterham boys:
31" Primaries 1 7/8 header dia
15" Secondaries 2 1/4"
3" collector dia at silencer
thats 31" from valve to 4-2 join then 15" from 2-1 ?
I'm more likely to go along the lines of the other guy:
27" primaries 1 7/8" dia
10" secondaries 2 1/4" dia
2 1/2" link pipe to silencer this is only about 3" long.
these sound longer than the way you have described it Nat?!
Ned.
[Edited on 2/2/06 by ned]
beware, I've got yellow skin
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NS Dev
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| posted on 2/2/06 at 11:12 PM |
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They are! Think I may have it wrong then, but the lengths I used worked for me on the grasser, but then without rolling-roading a really long primary
system I don't know if this would be better still!!!!
I think Simpson know what they are about, I'd be inclined to follow their suggestions!
Let me know what they/you find, and I'll follow suit with mine!!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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ned
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| posted on 2/2/06 at 11:15 PM |
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pah, that sort of info will cost ya 
..but on the phone they generlised and said for an xe somewhere around 24-28" primaries and 8-10" secondaries iirc..
Ned.
[Edited on 2/2/06 by ned]
beware, I've got yellow skin
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NS Dev
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| posted on 2/2/06 at 11:17 PM |
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LOL!!
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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