Which statement is correct about fuel calculations and injector sizing? Technician A says calculating the amount of fuel an engine needs helps determine the injector size. Technician B says BSFC calculates how much fuel is required to achieve the desired horsepower in a one-hour period.

Which statement is correct about fuel calculations and injector sizing? Technician A says calculating the amount of fuel an engine needs helps determine the injector size. Technician B says BSFC calculates how much fuel is required to achieve the desired horsepower in a one-hour period.

• A. Technician A
• B. Both
• C. Technician B
• D. Neither

Answer: (B)

Fuel delivery is guided by how much fuel the engine actually needs at a target power, which then sets the injector size. If you know the engine needs a certain amount of fuel to produce the desired power, you can pick injectors that can deliver that flow across the operating range and duty cycle. Technician A is right because determining the engine’s fuel requirement for the target power level directly informs how much fuel the injectors must be capable of delivering. Technician B is also right because BSFC (fuel per unit of power per hour) tells you how much fuel is needed to produce a given horsepower for a period of time. In practical terms, if you know the horsepower you want and you know the BSFC, you can estimate the fuel amount for that hour by multiplying BSFC by horsepower (and by the time, which is one hour). This helps confirm the fuel quantity the injectors must supply. Keep in mind that BSFC varies with RPM and load, so you’ll often use a range or map of BSFC values to refine injector sizing and fuel planning.

Fuel delivery is guided by how much fuel the engine actually needs at a target power, which then sets the injector size. If you know the engine needs a certain amount of fuel to produce the desired power, you can pick injectors that can deliver that flow across the operating range and duty cycle.

Technician A is right because determining the engine’s fuel requirement for the target power level directly informs how much fuel the injectors must be capable of delivering.

Technician B is also right because BSFC (fuel per unit of power per hour) tells you how much fuel is needed to produce a given horsepower for a period of time. In practical terms, if you know the horsepower you want and you know the BSFC, you can estimate the fuel amount for that hour by multiplying BSFC by horsepower (and by the time, which is one hour). This helps confirm the fuel quantity the injectors must supply.

Keep in mind that BSFC varies with RPM and load, so you’ll often use a range or map of BSFC values to refine injector sizing and fuel planning.