Engine Fuel Burn from Horsepower (BSFC)
The fuel burn in gallons per hour from engine power and brake-specific fuel consumption.
Example
You enter
- Engine power output (hp) 300
- BSFC (lb/hp-hr, diesel ~0.37) 0.37
- Fuel density (lb/gal, diesel 7.1 / gas 6.1) 7.1
- Tank size (gal, optional for run time) 200
You get
- Fuel burn 15.6 gph (111 lb/hr)
- Run time on tank 12.8 hours
Checked against published worked examples from: Boating magazine (B. Becker).
Details, formula, and sources
Scopelb/hr = HP x BSFC, gph = lb/hr / fuel density (diesel ~7.1, gasoline ~6.1 lb/gal), and run time = tank / gph. A 300 hp diesel at BSFC 0.37 burns 15.6 GPH (12.8 hours on a 200 gal tank); the same power from a gasoline engine (BSFC 0.50) burns 24.6 GPH, 57% more. The burn at the entered power; real duty-cycle burn is lower. A planning aid; the engine's fuel map and a measured burn govern.
Formula or tablegph = horsepower x bsfc / fuel_density; run_hours = tank / gph; diesel ~7.1 lb/gal, gasoline ~6.1 lb/gal.
Source and editionBrake-specific fuel consumption (BSFC) fuel-flow relation, standard engine-performance practice by name; first-principles mass-to-volume conversion.
Free accessThe BSFC fuel-flow relation (lb/hr = HP x BSFC) and fuel densities are standard published engine-performance results.
What governsEstimate. AHJ and licensed professional govern.
API field nameshorsepower, bsfc_lb_hp_hr, density_lb_gal, tank_gal, gph, run_hours
- BSFC flow lb/hr = HP x BSFC; gph = lb/hr / fuel densityengine-performance first principles
- Fuel density diesel ~7.1 lb/gal, gasoline ~6.1 lb/galfuel properties
- Full-power burn the burn at the entered power; part-load duty-cycle burn is lowerscope of this tile