Do modern exhaust headers make use of the self-canceling effect to reduce back pressure?
2006-12-21 02:51:00 · 4 answers · asked by ec_chica08 1 in Cars & Transportation ➔ Maintenance & Repairs
This is for school, I'm not repairing anything. Thanks!
2006-12-22 01:44:58 · update #1
No. They just provide a free flow, scavenging assist for the exhaust. This has little benefit though if you have a catalytic converter.
2006-12-21 02:55:23 · answer #1 · answered by robert s 2 · 0⤊ 0⤋
Most vehicles come from the factory with exhaust manifolds. Headers are normally an aftermarket product. If they are any good they will actually cause a small lowpressure infront of the other exhaust ports to enhance clearing the cyclinders of exhaust as they open. The best headers are called Equal Length headers. These can be a real PIA to install and do add a tiny bit of power as all cylinders the exhaust has to travel the same or equal distance.
A small bit of back pressure is recommended to increase the torque. Best example is Harley Davidson aftermarket exhausts. The straight through, unbaffled systems actually cause a drop in torque, so many install torque cones where the exhaust meets the head for minimal back pressure. Has to do with the venturi effect.
Happy Holidays
2006-12-21 10:59:21 · answer #2 · answered by shovelkicker 5 · 0⤊ 0⤋
Exhaust headers are tubes, that have a specific size and length.
The size of the pipe determines the velocity of the exhaust gases.
The length of the pipe determines timing of the reflected pressure wave back into the exhaust port.
Engines with "hot" cams has longer overlap (both intake and exhaust valves will be open at the same time). As the intake charge is drawn out of the exhaust with the negative pressure wave.
The headers will produce a positive pressure wave and push the intake back into the cylinder for more power. If the pressure waves arrive at the wrong time, you get a power loss.
This only works within a narrow RPM range and suitable for racing purposes. Street driving suffers due to the loss of low-end torque.
2006-12-21 11:30:16 · answer #3 · answered by SP_Rider 3 · 0⤊ 0⤋
I wouldn't waste the time with headers- they don't fit well, leak exhaust after a while, can make removing starters harder, and usually require butchering the rest of a perfectly good exhaust system.
2006-12-21 13:20:16 · answer #4 · answered by texczech1951 2 · 0⤊ 0⤋