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Old 07-26-2009, 01:35 PM   #4 (permalink)
frost
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There is some potential gain (1-2 mpg in my experience).
If we were to say there was NO gain to be had by an engine breathing better, we would also be saying that it doesnt matter how filthy an air filter gets, it won't affect your gas mileage.

Quote:
Originally Posted by kannibul View Post
Not really true.

The engine is an air pump...

The more air that goes through it, the more fuel that also goes through it to maintain the air-fuel ratio.

Fuel economy is more or less (these days) a function of efficency of the engine and drivetrain (how well heat is translated to movement) and aerodynamics and weight.
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