Specific fuel consumption converter
Convert specific fuel consumption between g/kWh, lb/hp·h and the thermal efficiency it implies.
That's 1.03× as thirsty as a truck diesel, while a car diesel is 1.15× thirstier. That is a thermal efficiency of about 42.06%.
What it means
How thirsty is that engine?
Efficiency figures assume diesel at 42.8 MJ/kg. Gasoline holds about 44 MJ/kg and hydrogen 120, so the same g/kWh means different efficiencies for each.
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Three things worth knowing
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Lower is better
200 g/kWh is about 42% thermal efficiency; 400 g/kWh is 21%. Every gram saved is work the fuel actually did.
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Why "brake"
The power is measured at the output shaft with a brake — a dynamometer — rather than calculated from the cylinder pressure. It counts every internal loss.
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It is not miles per gallon
BSFC measures the engine, not the vehicle. A very efficient engine in a heavy, badly geared car still returns poor fuel economy.
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Background
About specific fuel consumption
BSFC is the fuel an engine burns for each unit of work it produces, so it compares a ship engine with a chainsaw fairly. A large marine diesel manages 165 g/kWh — better than 50% efficient — while a small two-stroke may use four times as much.