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Old 04-14-2009, 10:01 PM   #18 (permalink)
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Quote:
Originally Posted by Frank Lee View Post
First things first: how much loss is there from a few turns?

And: When is a straight exhaust path beneficial- if at all- i.e. is this thing going to be run at WOT at high rpms a high percentage of the time?

Can you find an example of a perfectly straight exhaust system... anywhere on anything?
1 - The gains surely wouldn't justify the expenses of labor and research/development. There is obviously "lower hanging fruit".

2 - A straight exhaust path would be beneficial if properly designed, even under low RPM circumstances. A straight path could be designed to be non-restrictive and still provide optimum flow for the exhaust gasses at a given engine speed/volume output. The length and stepped sizing of the exhaust could be tuned accordingly to create the harmonic scavenging of exhaust flows, creating a sort of "super efficient" area in the engine's operating range. Obviously, that area should be the most often used speed.

Inversely, scavenging can be had simply by combining the exhaust pulses, which a true straight exhaust simply cannot do.

3 - Jet engines?
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