Quote:
Originally Posted by Katmandu
Of course they do.  |
I'm not aware of any credible/reliable evidence that a free flowing exhaust will improve fuel efficiency at the engine speeds most eco-drivers operate.
From
Fuel saving gadgets - a professional engineer's view
Quote:
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Another frequent argument is that the intake and exhaust systems of "stock" engines are too restrictive, that is to say it takes a lot of power just to suck the air in and blow the exhaust out. By reducing this loss, not only is power increased, but fuel economy gets better as well. In theory there is a hint of truth in that, but in practice the difference between a "stock" and aftermarket performance exhaust or intake system only really makes itself felt at times of maximum gas flow (full throttle, maximum engine speed - or close to it). Under normal crusing conditions the losses in even the standard system are so low that the effect on economy is vanishingly small.
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