shortys vs longs

[leblanc]

Could you please tell me what the advantage is of a long header vs a shorty. I know that the shorty has smooth bends and allows you more usable space around the motor but does it hurt performance much? It can't be too bad right?

 

[dgc333]

Here are some rules of thumb regarding headers.
*Tube diameter will determine the rpm of the torque peak.
*Longer tubes will enhance the power below the peak vs shorter tubes above the peak.
* Longer collectors increase power below the peak and shorter above the peak.

For a street motor you want as much power below the peak as you can get. Long tubes are the way to go if you are looking to increase power.

 

[demon seed]

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