Mustang Fuel Injector Overview
Mustang Fuel Injector Overview
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Having the right fuel and air mixture relies on key components of your Mustang's fuel delivery system all working in tandem with each other. If one of these components is under performing, replacing it can save you from damaging the motor and the performance of your Mustang.
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If your Mustang is running rough or idling poorly, it may be time to get a new set of injectors or grab an upgraded set for a high horsepower ride.
Mustang Fuel Injectors
Fuel Injectors, as the name suggests, are responsible for injecting the fuel into your Mustang’s engine. A fuel injector atomizes the fuel by forcibly pumping it through a small nozzle under high pressure into the combustion chamber where it is ignited. This atomization allows the fuel to burn more completely, releasing all its potential energy, which translates into better fuel economy and more power.
Injector Nozzle Close Up
Mustang Injector Flow Rates
As stated above, fuel injectors are under pressure, which is known as flow rate. A fuel injector’s flow rates are measured in “pounds per hour” and are available in different sizes depending on application. AmericanMuscle carries fuel injectors ranging from 19 lb/hr up to 120 lb/hr, but you never want to upgrade your Mustang’s fuel injectors to a larger size unless it is absolutely necessary. Too large a fuel injector will cause your engine to run rich, which will actually cause you to lose power. Bigger is not always better.
The basic formula for calculating the correct size fuel injector for your Mustang is: Injector Flow Rate (lb/hr) = (Engine HP) x (BSFC) / (Number of Injectors) x (Injector Duty Cycle)
Engine Horsepower (a.k.a. brake horsepower) is measured at the flywheel, NOT at the rear wheels. BSFC (Brake Specific Fuel Consumption) represents how much fuel (in lb) that’s required per hour per each brake horsepower the engine produces. BSFC is usually a number between 0.4 and 0.7 for gasoline engines. BSFC can be estimated but for best results, the actual number measured on a Dyno should be used.
- For naturally aspirated engines, estimate the BSFC to be 0.4 to 0.5
- For nitrous engines, estimate the BSFC to be 0.5 to 0.6
- For forced induction, estimate the BSFC to be 0.6 to 0.7
Injector Duty Cycle refers to how long the injector needs to be open (flowing fuel) in order to supply the required amount of fuel. If the injector has a 100% duty cycle, it means it is open all the time injecting fuel whether the valves are open or closed. This will cause unburned fuel to be blown past the exhaust valve or to be poorly atomized, which results in poor combustion, loss of fuel economy and power. Because of this, it’s generally recommended to select an injector with a high flow rate that does not exceed an 85% (0.85) duty cycle.
Example: A 300HP naturally aspirated V8 Mustang requires what size fuel injector? Injector Flow Rate = 300 (HP) x 0.5 (BSFC) / 8 (Number of injectors) x 0.85 (duty cycle). The Injector Flow Rate would equal 22.05 lb/hr or 24 lb/hr, rounding up to the next popular injector size available.
Fuel Injector Body Style
Fuel injectors are available in (3) distinct body styles: EV1, EV6 and EV14. The EV1 and EV6 injectors are commonly referred to as “long”, where the EV14 is known as “medium”. Newer mustang years (2011 and newer) all utilize an EV14 injector style. While the sizes can vary (lb/hr), the style is consistent across the board from the 4 cyldiners to the 5.0!
Connector Style: There are (2) types of electrical harness connectors used on fuel injectors: USCAR and Jetronic/Minitimer (a.k.a. Bosch/Amp). The USCAR is a rounded, square shape and the Jetronic/Minitimer is a rounded, rectangular shape.
What Fits What?
As any Mustang owner knows, Ford loves to make changes to their vehicles on every model year from interior styling to what nuts and bolts are needed to hold it altogether; unfortunately, fuel injectors are not immune from these changes. This can be very confusing when working on your own Mustang so here is a list of what type of fuel injectors Ford used throughout the generations:
EV1 (Jetronic/Minitimer) is used in:
- 1987-2004 LX 5.0, GT, Bullitt
- 1994-1998 V6
EV6 (USCAR) is used in:
- 1999-2004 V6
- 2005-2010 GT
- 1999-2001 Cobra
- 2003-2004 Cobra
- 2003-2004 Mach 1
EV14 (USCAR) is used in:
- 2005-2010 V6
- 2011-2017 GT
- 2007-2014 GT500
What Flow Rates Came From the Factory?
As the progression of engines has continued, the higher power levels have demanded a larger fuel delivery system. In order to fuel the new power, larger, newer style fuel injectors started becoming a vital part of an engine setup. The first year of modern fuel injection in a production mustang was 1986. They came with 19lb/hr injectors. This size was continued on GT models (and some other special editions) until 2005. In 2005, with the release of the 4.6 3v (3 valves per cylinder), injector size was bumped up to 24 lb/hr in order to accomodate the additional power. In 2011, with the release of the Coyote 5.0, injector size has once again increased in size. As it currently sits, injectors are 32 lb/hr.
Cobras had different injectors for different years. From 2003/2004, when they utilized a supercharger, the injector size was 39 lb/hr. Years prior to 2003 utilized 24 lb/hjr injectors.
Injector Conversion Kits For Mustangs
In the event you’re using a custom or aftermarket harness, there are conversion kits available that allow you to convert your connectors from Jetronic/Minitimer to USCAR and reversely from USCAR to Jetronic/Minitimer. These are great for engine swaps and hot rod builds.
Injector Adapter Kit
To Upgrade or Not to Upgrade?
Hopefully this article has taken some of the mystery out of fuel injectors and will help you make a more informed decision when it comes time to replace or upgrade your Mustang’s injectors. If your Mustang is bone stock or has minor bolt-ons like a Cold Air Intake, Under-drive Pulleys or a Catback Exhaust, the original factory size fuel injectors are perfect for these applications. If you’re running a forced induction setup or your engine is heavily modified, you’ll need to use the formula listed above to find the correct size fuel injectors needed for your application.
Note: While changing spark plugs is never a bad idea, it is not mandatory to change them when changing fuel injectors. However, it would not hurt to pull them and check that they are in good condition.
Fitment includes: 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, GT, V6, Cobra, ShelbyGT500, Mach1, Bullitt, Boss, LX, SVO, EcoBoost