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Author: Subject: Priamry and Secondary pipe lengths for exhaust manifold?
ned

posted on 2/2/06 at 10:05 PM Reply With Quote
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]





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NS Dev

posted on 2/2/06 at 10:55 PM Reply With Quote
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.





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ned

posted on 2/2/06 at 11:07 PM Reply With Quote
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]





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NS Dev

posted on 2/2/06 at 11:12 PM Reply With Quote
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!!





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ned

posted on 2/2/06 at 11:15 PM Reply With Quote
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]





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NS Dev

posted on 2/2/06 at 11:17 PM Reply With Quote
LOL!!





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