Quote:
Originally Posted by aerohead
Both have engineered backpressure into their products for low speed economy,then provided short-circuiting for high speed efficiency
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Here,YAMAHA (read Ford SVO engine builder) designs it's 'smart' exhaust,with computer-controlled valving to maintain optimum backpressure under all load conditions
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Sorry Aerohead, but you are a little off here. Both of these systems restrict
flow to alter the pulse timing causing a negative pressure wave that travels back down the header tube and hits the cylinder head when the exhaust valve opens. These systems actually
reduce pressure at that RPM.
Backpressure is
never desired.
For a good semi-technical talk about exhaust design see: