shortys vs longs

One reason that headers help with thru put of the engine is their ability to scavenge the exhaust system. Lets just look at one 4 into 1 header. As cylinder one fires and the piston starts to come back up for the exhaust stroke the exhaust is pushed out thru the header pipe and when the exhaust flow meets the collector it actually causes a scavenging effect (sucking or pulling)of the remaining 3 pipes. This helps get rid of exhaust gases that like to sit up against the exhaust valves. This scavenging effect is also felt at the combustion chamber during the overlap event when both the intake valves and exhaust valves are open and the piston is going past TDC for the beginning of it's intake stroke. The end all be all is that long headers have a larger scavenging effect on the engine than short headers. IMO most mild turned street engines will not see the difference, drags cars diffentially would.

Wow I've still got some brain cells left.:evil2::evil2::evil2::evil2:

Terry