More torque?

MiracleMax · 08-01-2001, 12:41 AM

Gears, pulleys, not to radical exhaust

laugh will you will, but on a stock engine or nearly stock (stock cam/heads/intake), an 1-1/2 header with a good H or X pipe and some decent mufflers will probably keep exhaust gas velocity up and keep from over scaveging the engine.

Any backpressure present is force the engine has to exert against, sucking up power. I find it interesting folks maintain a little bit of backpressure is good for power? Probably what they are refering to is a little bit to much exhaust scavenging is bad for power especially in a fuelie application (nothing like massive unburnt A/F mix running across an oxyegen sensor!)

Anywhosit, what you want to accomplish is complete evacuation of the cylinder minimizing or elminating "negative torque" acting against the piston, furthermore if you can achieve a state where there is a vaccum present in the cylinder as the intake opens and allows fresh A/F into the cylinder, its like geting a little boost from supercharging.

The former is what is probably accomplished by most exhaust systems. the latter is a tricky affair and requires a tuned exhuast system that is sensetive to the timing events of the engine. Since the exhast will use refraction (sp?) waves to provide for the enhanced scavaging which is similar to the technique used in a tuned intake manifold to achieve the same super-charging results

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08-01-2001, 12:41 AM	#2
MiracleMax Registered Member Join Date: Apr 1999 Location: Hayes, Va, USA Posts: 798	Gears, pulleys, not to radical exhaust laugh will you will, but on a stock engine or nearly stock (stock cam/heads/intake), an 1-1/2 header with a good H or X pipe and some decent mufflers will probably keep exhaust gas velocity up and keep from over scaveging the engine. Any backpressure present is force the engine has to exert against, sucking up power. I find it interesting folks maintain a little bit of backpressure is good for power? Probably what they are refering to is a little bit to much exhaust scavenging is bad for power especially in a fuelie application (nothing like massive unburnt A/F mix running across an oxyegen sensor!) Anywhosit, what you want to accomplish is complete evacuation of the cylinder minimizing or elminating "negative torque" acting against the piston, furthermore if you can achieve a state where there is a vaccum present in the cylinder as the intake opens and allows fresh A/F into the cylinder, its like geting a little boost from supercharging. The former is what is probably accomplished by most exhaust systems. the latter is a tricky affair and requires a tuned exhuast system that is sensetive to the timing events of the engine. Since the exhast will use refraction (sp?) waves to provide for the enhanced scavaging which is similar to the technique used in a tuned intake manifold to achieve the same super-charging results