Quote:
Originally Posted by Hyper4mance2k
No engine in the history of 4 stroke internal combustion needs backpressure. The exhaust needs velocity to scavenge all the spent energy from the combustion chamber. There are may ways to do this, but back pressure is not one of them. You are parroting misinformation and a lack of understanding of fluid dynamics.
For an engine to make peak torque at any RPM it must expell as much exhaust as it can at any given RPM. The key to doing this is exhaust gas velocity, not back pressure. Correct diameter pipes that maintain exhaust gas velocity, at the desired RPM and throttle position, are the key to making power.
The reason the back pressure myth continues is bacuse of people putting on too large of an exhaust system which is only effective at a small and high RPM range. At other RPMs and throttle positions too large of an exhaust pipe will cause the exhaust gas to have little to no gas velocity, and can add turbulant exhaust flow which will ultimately cause low RPM drivability issues; it's the reduction in velocity and flow rates that casue problems, not the reduction in back pressure.
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It's times like this that make me wish I'd majored in mechanical or aerospace engineering instead of EE.
Thanks for the lesson (without the math... otherwise I'd need to go dig up my old college notes).
