ORIGINAL: codiddley
Whats this I hear about people piping 4 strokes? I don't get it at all. The pipe would do nothing because the motor has an INTAKE stroke, and the exhaust valve would be closed when the pulse hit the engine.
Anybody?
Not true.
Why do you think people put Flo-Master exhausts on their cars? I know they sound cool, but they also aid in scavenging. All engines perform the same task weather 2c or 4c, they are air pumps. They both have exhaust pulses as well (the two stroke has twice as many though for a given RPM) By tuning the length and diameter of the exhaust system, you can adjust the torque curve on a 4c the same way as you would on a 2c. I think most of the 4c tuned systems are designed to extract extra RPMs though as these engines come out of the box set up with mufflers designed to produce the power in the low and mid range.
I don't think the benefits of a 4c tuned system would as great as with a 2c system though because the cam profile has so much to do with where the powerband of the engine is.