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Old 03-22-2008, 03:27 PM   #9 (permalink)
aerohead
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exhaust thrust

NASCAR teams would like to have the exhaust exit behind the racecar,however,are forbidden to do so by the rulebook.Of course,in a race situation,they're looking for any edge they can get.Drafting would place the following driver in a position to breathe concentrated exhaust,so perhaps its better the tailpipes remain where they are.In a commuting environment,and at the RPMs that engines typically develop,the volume of gases being expelled out the tailpipe,and the exit velocity at which they're being discharged,I believe would render a "thrust" of dubious value.As to the issue of tailpipe size,my opinion is,that for normally-aspirated Otto-cycle gasoline engines ( and no Nitrous oxide either!),that the inside diameter of the tailpipe should be about the same size as that of the throttle-body,for MFI/EFI,or the combined area of carburetor throttles.
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