BSFC Calculator - Brake Specific Fuel Consumption

Your details

Mass of fuel consumed per hour. Use g/h in metric mode, lb/h in imperial mode.
g/h
Shaft (brake) power delivered by the engine. Use kW in metric mode, hp in imperial mode.
kW
Fuel type sets the lower heating value (LHV) used to calculate thermal efficiency. BSFC itself is fuel-independent.
Switch on to enter torque and RPM rather than a direct power figure. Power = torque x angular velocity.
BSFCGood efficiency
250g/kWh

Brake specific fuel consumption in metric units

BSFC (imperial)0.411lb/hp-hr
Thermal efficiency0.3%
Fuel mass flow8.3333g/s
250 g/kWh
Excellent<200Good200-280Average280-360Below average360-450Poor450+

BSFC is 250.0 g/kWh (0.4110 lb/hp-hr).

  • Thermal efficiency is 32.7%, meaning 32.7% of the chemical energy in gasoline is converted to useful shaft work.
  • This is comparable to a modern turbocharged direct-injection diesel passenger car running near its peak efficiency island.
  • BSFC varies significantly with engine speed and load. The lowest BSFC (best efficiency) is found near peak torque with a wide-open or lightly throttled intake.

Next stepIn imperial units this is 0.4110 lb/hp-hr. Engine mapping software plots BSFC contours against RPM and load (BMEP) to help calibrators target the best-efficiency island.

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