ELI5: Explain Like I'm 5

Brake specific fuel consumption

When a car or an airplane moves, they typically use fuel to do so. Brake specific fuel consumption (BSFC) is a way to measure how much fuel (gasoline, diesel, or aviation fuel) is required to make the vehicle move a certain distance or power a machine for a certain duration.

Think of it like how much food you eat to run for a certain distance or play for a certain amount of time. If you eat too much food, you will feel too heavy and sluggish, but if you don't eat enough, you will get tired and run out of energy.

Similarly, if a vehicle uses too much fuel to move a certain distance, it will be less efficient and may not be able to go as far or as fast. On the other hand, if it doesn't use enough fuel, it will not be able to generate enough power to do its job.

BSFC is measured in grams of fuel per unit of power produced, usually in horsepower or kilowatts. The lower the BSFC, the more efficiently the vehicle is using fuel.

For example, if a car has a BSFC of 250 grams per kilowatt-hour (g/kWh), it means that it requires 250 grams of fuel to produce one kilowatt of energy for an hour. A more efficient car might have a BSFC of 200 g/kWh, while a less efficient car might have a BSFC of 300 g/kWh.

By measuring BSFC, engineers can design more efficient engines, develop better fuels, and optimize the performance of vehicles to reduce the amount of fuel they consume and therefore reduce their environmental footprint.