tooter's manifold adventure...

[xnamerxx]

Originally Posted by Shinare

^^^ RE: "long tube header" - Please forgive this noob question, it really is a question and not a troll, but why does it matter the length of a pipe? Don't you want the exhaust to just get out via the back of your car rather than in the engine bay?

Its about exhaust scavenging. At a certain length and diameter, the exhaust pulse will create a sonic negative pressure wave at the valve creating a vacuum. That vacuum helps pull up on piston, clear out the cylinder, and suck fresh air into the cylinder. The exhaust itself still exits in the original location in most situations. On most otto cycle engines exhaust contributes to about 5-15% of the engines theoretical performance potential, on 2 stroke engines it can be as much as 40%.
In my case I picked up 7hp and 6 tq over a DC header with the long tube header I designed.