Brake Specific Fuel Consumption (BSFC)
This is the ratio of the engine fuel consumption to the engine power output as measured at the flywheel. BSFC has units of grams of fuel per kilowatt-hour (g/kWh) or pounds mass of fuel per brake horsepower-hour (lb/bhp-hr).
BSFC is a measure of engine efficiency.
η = Engine Efficiency
BSFC = Brake Specific Fuel Consumption [g kWh-1]
LHV = Lower Heating Value of fuel used by the engine [kWh g-1]
The BSFC is dependent on engine load and speed. Typically the BSFC is poor at low load, maximum load and at idle and high speed - this leaves a minimum somewhere in the centre of this map. This minimum is what is normally quoted for an engine.
|Turbo-prop aircraft engine at max power||295g/kWh|
|Turbocharged petrol car engine||245g/kWh|
|Turbocharged diesel car engine||205g/kWh|
|Large marine diesel 2-stroke||160g/kWh|
P. J. Shayler, J. P. Chick and D. Eade, "A Method of Predicting Brake Specific Fuel Consumption Maps", SAE 1999-01-0556