BSFC stands for Brake Specific Fuel Consumption. It tells you how much fuel your engine will use per hour for each horsepower it makes. BSFC changes with engine load and rpm.
A lower BSFC value is MORE efficient. Higher BSFC numbers are LESS efficient.
How is it calculated?
BSFC can only be measured on a dyno. The formula is:
BSFC = lbs. of fuel used per hour ÷ horsepower
For example, a 300hp engine using 150 lbs./hr. of fuel would have a BSFC of 0.5.
Different engines using different fuel types will have different BSFC values. The table below lists some general BSFC values to use when making calculations.
| Gasoline | E85 | Methanol | |
| Normally Aspirated Engines | 0.45-0.5 | 0.63-0.70 | 0.9-1.0 |
| Engines Using Nitrous Oxide | 0.6-0.65 | 0.84-0.91 | 1.2-1.3 |
| Forced Induction Engines | 0.6-0.75 | 0.84-1.05 | 1.2-1.5 |
*Note* Power adders increase horsepower but not efficiency. They lose efficiency to heat, friction, and pumping losses. In reality, they use more fuel to make more power. That’s why they have higher BSFC values.
Why is it important?
BSFC is used in several fuel system calculations:
BSFC is an excellent tuning aid on the dyno.