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Old 10-03-2011, 06:23 PM   #335 (permalink)
darcane
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Quote:
Originally Posted by beatr911 View Post
"Efficiency" can mean many things. It depends on how it's defined

To a racer it can mean how much power can this thing put out, measured in horsepower. It can also mean how full can the cylinder be filled on each stroke, measured in maximum torque. It could also be defined as the area under the torque curve that shows how full the cylinder fills over a useable or defined RPM range. All of these are measured at full throttle, meaning there is little restriction in the intake system. We usually don't ride full throttle for extened periods on the street and expect fuel efficiency so these numbers probably don't apply for our purposes.
Actually, it isn't...

Plain and simple, efficiency is a ratio of output to input. Horsepower and torque don't describe a ratio, and thus aren't efficiency ratings. In general, increasing volumetric efficiency will increase horsepower and torque, but that doesn't mean the latter are efficiencies.

BSFC is a measure of efficiency since it is a ratio of output (brake power) to input (fuel consumption).
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