ERIKC DLLA 148P 924 fuel denso injector nozzle DLLA 148P924 common rail injection nozzle DLLA148P924

FAQ: What is an injector’s static flow rate?

ERIKC Answer:Manufacturers rate fuel injectors by the maximum amount of fuel that they can flow in a given amount of time. This measurement is taken with the injector on 100% of the time (100% duty cycle, or wide open) and with the fuel at a given pressure (usually 43.5 psi). For example, a 19 pound per hour (Lb/Hr.) injector flow 19 pounds of fuel in one hour at 100% duty cycle and 43.5 psi of fuel pressure. Injectors in imported vehicles are often rated in cubic centimeters per minute (cc/min) instead of pounds per hour. This is also done at 100% duty cycle.

If injectors should not exceed 80% duty cycle under operating conditions, why do manufacturers rate them at 100% duty cycle?

A test at 100% duty cycle is used to determine the maximum amount of fuel that will flow through an injector in a given time. This test is useful for determining whether an injector’s internal fuel passages were machined properly, but it does not check an injector’s ability to cycle on or off. It is usually not recommended to run an injector at more than 80% duty cycle under actual driving conditions. This 80% duty cycle operating limit is taken into account to make sure the injector will be large enough to feed the engine under actual operating conditions and will not starve the engine for fuel.