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Author Topic:   Exhaust pipe length
MEANGENE83
Member
posted December 03, 2003 07:22 PM
I need to run new exhaust due to IMCA hobby rule change. We have to run 2" duals no crossover. Any suggestions for length of pipe to start with? I'm going to paint em and cut em off but don't know how long of pipe to start with.


66jj
Member
posted December 03, 2003 10:14 PM
you should run a min of 2 ft, motors need some back pressure.

I would run it out from under the car on the drivers side so you can hear when you get old. but thats me Im gonna run mufflers on a Imca stock car..

dirtrace54
Member
posted December 04, 2003 07:27 PM
paint it and cut it off 18 inches after the point of where they paint was no longer burnt off.


66jj
Member
posted December 04, 2003 07:31 PM
ahh, I tried to use that method to locate my crossover. thing is diff paint and or diff jetting sure makes a big diff in how far the paint stays. I ended up using a pyrometer after pullin in the pits and checking for the temp drop.



ratracer10
Member
posted December 05, 2003 11:21 AM
thanks for the replys guys, ratracer this is for a car restricted to manifolds so I don't know if the same theory applies to headers, anyway you cut off the exhaust where the gas cools to try to scavenge the cylinders. The theory is that where the exhaust gas cools it shrinks thereby creating a low pressure area, hopefully sucking the exhaust out of the pipe.


66jj
Member
posted December 05, 2003 09:11 PM
exhaust is still burning in the pipes, some back pressure is good, to pre heat the cylinder for the next time it fires.

on headers or manifolds you should deffinitely run at least enough pipe past where the temp drops off. that way your not dumping out the needed heat. 2 feet sticks in my head minimum for manifolds, maybe its 2 feet past where it changes temp, I dont remember for sure.

but if you look at most dirt cars I guess they have a whole lot more money and hp than I do, since they give some hp away with their lack of exhaust.

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