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Old 11-16-2015, 07:37 PM   #17 (permalink)
aerohead
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Quote:
Originally Posted by darcane View Post
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:
In the common vernacular,if one observed a manufacturer wittingly installing a longer path,or mutilated structure within the pathway of a duct,they might presume that some thought went into that extra cost and difficulty of manufacture.
When they claimed a benefit to that more tortuous pathway they would be implying an advantage with respect to performance.
Since an internal combustion engine must operate under transient conditions,from idle,low speed operation,up to redline,under full load,it appears that considerations are being made to optimize performance as best they can,for a market basket of different operational environments.
My internal combustion textbook mentioned 'tuning' of the exhaust system by the manufacturer,to optimize the full spectrum of operation.
Back pressure was intentionally designed into the system for low speed operation.My personal racing experience has demonstrated that 'backpressure' (in the common vernacular) was essential to top engine performance.
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