Ford Mustang Stock Fuel Injector Size Chart

Posted 4/11/2017 by Tyler Rodriquez

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Mustang Stock Fuel Injector Size Chart


Mustang fuel injectors are a vital part of your motor as they supply your engine with the correct amount of fuel for your application. Knowing your stock Mustang fuel injector size can help you in judging if you have the correct size injectors for your application.


Mustang Stock Fuel Injector Size Chart - Mustang Stock Fuel Injector Size Chart

Calculating Fuel Injector Size

The formula for calculating the correct size fuel injector for your Mustang is calculated by:
Injector Flow Rate (lb/hr) = (Engine HP) x (BSFC) / (Number of Injectors) x (Injector Duty Cycle)

If you are trying to compare injector flow rates and you have flow data at one delta pressure, you can easily calculate the flow rate at a different delta pressure as follows:
Flow rate at new delta pressure = (flow rate at old pressure) x v(new pressure/old pressure)

Engines require a certain fuel flow rate that is generally measured in lb/hr (pounds per hour) and can be calculated via knowledge of its Brake Specific Fuel Consumption (BSFC). BSFC represents how much fuel (in lb) is required per hour per each brake horsepower the engine produces. More clearly stated, this means that if you have a gasoline engine that makes 300 brake horsepower, its total maximum fuel requirement in lb/hr can be calculated as follows:
Fuel flow requirement = (brake horsepower) x (BSFC)

This calculation can also be reversed to give the maximum safe hp a set of injectors can support, which gives:
Max safe hp = [ (injector size) x (total # of injectors) x (max duty cycle) ]/BSFC

Example: The following guide is a general rule of thumb for sizing fuel injectors on an 8-cylinder engine using a BSFC of 0.50. Forced-induction engines typically range from a BSFC of 0.55 to 0.65, with the latter value arising from the fuel enrichment necessary to keep exhaust temperatures below 1650 deg F and catalyst temperatures below 1750 deg F.

Naturally Aspirated: (19 lb x 8 x .85)/.50 = 258.4 or approx 258 hp @ 85% duty cycle Forced-Induction @ 0.55: (19 lb x 8 x .85)/.55 = 234.9 or approx 235 hp @ 85% duty cycle Forced-Induction @ 0.65: (19 lb x 8 x .85)/.65 = 198.8 or approx 199 hp @ 85% duty cycle

Inj Flow Rate (@ 40 psid) Naturally Aspirated hp (@ 0.50) Forced-Induction hp (@ 0.65)
19 lb/hr 258 hp @ 85% Duty Cycle 199 hp @ 85% Duty Cycle
24 lb/hr 326 hp @ 85% Duty Cycle 251 hp @ 85% Duty Cycle
30 lb/hr 408 hp @ 85% Duty Cycle 314 hp @ 85% Duty Cycle
32 lb/hr 435 hp @ 85% Duty Cycle 335 hp @ 85% Duty Cycle
34 lb/hr 462 hp @ 85% Duty Cycle 356 hp @ 85% Duty Cycle
36 lb/hr 490 hp @ 85% Duty Cycle 377 hp @ 85% Duty Cycle
38 lb/hr 516 hp @ 85% Duty Cycle 398 hp @ 85% Duty Cycle
39 lb/hr 530 hp @ 85% Duty Cycle 408 hp @ 85% Duty Cycle
42 lb/hr 571 hp @ 85% Duty Cycle 439 hp @ 85% Duty Cycle
44 lb/hr 598 hp @ 85% Duty Cycle 460 hp @ 85% Duty Cycle
47 lb/hr 639 hp @ 85% Duty Cycle 492 hp @ 85% Duty Cycle
60 lb/hr 816 hp @ 85% Duty Cycle 628 hp @ 85% Duty Cycle
72 lb/hr 979 hp @ 85% Duty Cycle 753 hp @ 85% Duty Cycle
80 lb/hr 1088 hp @ 85% Duty Cycle 837 hp @ 85% Duty Cycle
98 lb/hr 1333 hp @ 85% Duty Cycle 1025 hp @ 85% Duty Cycle

Remember, the above calculations assume a fuel pressure of 39.15 psid. If you can raise fuel pressure and still be sure that your fuel pump can supply the desired flow rate, then these maximum horsepower numbers will increase.