Quote:
Originally Posted by eufo
I think I'm the audience because I don't know what BSFC is... LOL! Seriously, though, what is it? I have always felt like accelerating too slowly isn't beneficial to MPG, so it is nice to see this confirmed.
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BSFC stands for Brake Specific Fuel Consumption. It's a measure of engine efficiency. The "brake" doesn't refer to the brakes on a vehicle, but rather a dyno brake (a tool used to measure the power output of an engine).
The best way to think of BSFC is the ratio of fuel input to mechanical energy output (lower is better). The units are typicaly lbs/hp-hr in US units & g/kW-hr in metric units.
Note that BSFC doesn't capture
how much energy is being produced, only
how efficiently that power is being made--i.e., how much fuel does it take to produce a certain amount of work.
Vehicle parameters (vehicle weight, amount of braking, vehicle speed, etc, drag, rolling resistance, etc.) determine the
amount of work required to travel a certain distance (hp-hr/mi), whereas engine parameters (speed, throttle, intake temp, etc) determine the BSFC (lb/hp-hr). Put those two things together: (hp-hr/mi)*(lb/hp-hr) and you get lb/mi. All you need then is fuel density (lb/gal) to get miles/gallon.