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Engine fuel consumption formula
by Alex
Expert answer:
Quick answer
Basic formula: Fuel Consumption = (Fuel Flow Rate) × (Operation Time). For mpg, miles traveled ÷ gallons used. For engines, often in g/hp·hr (BSFC).
Detailed answer
In engineering, the simplest approach is Fuel Flow Rate × Time = Total Fuel. If you run an engine at a certain flow rate (like 5 gallons per hour) for 2 hours, you use 10 gallons total. Vehicles measure mpg by dividing distance traveled by gallons consumed.
For a more technical engine measure, you use BSFC (Brake Specific Fuel Consumption) in grams per kilowatt-hour or lb/hp·hr. Knowing horsepower output and engine load yields how much fuel is burned per hour. Combining that with operating hours or mileage gives total consumption.
These formulas form the backbone of analyzing efficiency, planning refuels, or comparing engine designs. In real-world driving, conditions vary flow rate constantly, so we average it over a trip or track data across fill-ups.