Mark Houlahan
Brand Manager, Mustang Monthly
June 4, 2012

When vintage Mustang enthusiasts think fuel injection conversions, their minds often visualize the popular late-model 5.0L engine swap with its long runner, two-piece manifold, port fuel injection setup with fuel rails, and a myriad of sensors and wiring. The look just doesn't seem right to many and the installation headaches can be migraine in nature with trying to trim down the OE wiring, getting the stock computer to work in a car some 40 years older than it was designed for, and so forth. Even the underhood packaging can become an issue, as the stock 5.0L induction path often interferes with shock towers, shock braces, and even the location of the battery and other underhood bolt-in components.

The solution we've found to having all the benefits of electronic fuel injection without the installation hassles or having the engine bay look like an electrical sub panel for the space shuttle is to use a throttle body–based system that bolts on in place of your carburetor. These systems can range in ability from near stock to upwards of 1,000 horsepower. So there's certainly a system that will feed your engine, be it a lightly warmed-over 289 or a 427-cube stroked Windsor. If your Mustang is running a 4150/4160 Holley-style bolt pattern intake (pretty much any aftermarket intake ever designed for small- and big-block Ford engines), one of these kits will bolt right on in an afternoon.

Best of all, with the 4150 flange mounting configuration, these EFI systems feature a standard 5-1/4-inch air cleaner mounting base as well. You can easily reuse your stock air cleaner or any aftermarket air cleaner assembly and keep those retro "carb'd" looks.

There are several companies offering throttle body–based fuel injection, and each system has its own set of features and tuning abilities. Not to mention, some kits are more inclusive with their sub system parts. Finally, some of the available throttle body–based systems require a traditional fuel return line to the fuel tank, while others feature a more modern "returnless' fuel system that requires but one high pressure line to the throttle body (akin to the '99 and up Mustang fuel system), which helps further the illusion of a carburetor and its dual feed fuel inlet.

We've gathered up the currently available systems and gone through their feature sets, options, pricing, and more to offer our readers an easy-to-understand buyer's guide that will help you choose the right EFI system for your vintage Mustang. Better cold starts, increased fuel economy, more horsepower, and a smoother idle awaits you.

Edelbrock E-Street EFI

The folks at Edelbrock know a thing or two about EFI and have offered port-injection setups and even EFI crate engine packages for many years. Just as we were wrapping up our story, we heard about Edelbrock's latest foray into fuel injection, the E-Street EFI system, a 4150 square-bore flange-style EFI that bolts on in place of your existing carburetor. Edelbrock's system is designed for V-8 engines and will be available in both a traditional return-style fuel system as well as the newer returnless EFI setups we're seeing from the OEs. Some of the features Edelbrock designed into its new system include progressive throttle linkage, wideband oxygen sensor for accurate fuel control, and an industry first 7-inch tablet that allows easy tuning and control of the system via wireless Bluetooth connectivity. The tablet will also allow full manual tuning for those versed in EFI tuning and it also features a dashboard function to display your engine's EFI parameters. Eventually Edelbrock plans to offer systems tuned for four- and six-cylinder engines as well as the popular "dual four" look with two throttle bodies on one intake manifold.

System Specs:

  • 4150-style cast 1,000-cfm throttle body with 60 lb/hr fuel injectors and fuel rails
  • 600 horsepower capability level
  • All sensors integral to throttle body (except wideband O2)
  • Separately mounted ECU
  • Wideband O2 sensor and weld-in bung
  • Dynamic fuel control that self- adjusts the fuel curve
  • Wireless 7-inch tablet with touch screen for tuning
  • Optional electronic ignition control (requires external coil driver or CD ignition box)
  • Optional fuel system components to finish installation will be available
  • Price TBD (available Q3 of 2012 according to Edelbrock)

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FAST EZ-EFI

Fuel Air Spark Technology, more commonly known as FAST, developed its EZ-EFI system to take all of the hassle and trepidation out of adding EFI to a carbureted vehicle. Bolting on in place of a standard four-barrel carburetor, the FAST EZ-EFI system features patented self-learning control strategies and requires the user to answer a few basic questions via the hard-wired LCD hand-held display module. With a four-wire hook up (optional wires for A/C idle speed, cooling fan, and fuel pump), it couldn't be easier. The EZ-EFI throttle body ships fully assembled and bolts on in minutes. Just plumb your return-style fuel system, mount the ECU, and install the included wideband O2 sensor and you're ready to roll. Options include internal and external fuel pump kits, dual-quad upgrade kit, fuel hose kit, in-vehicle mount for hand-held controller, and electronic transmission controller for modern overdrive electronically controlled transmissions.

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System Specs:

  • 4150 carb flange throttle body with 88-lb/hr injectors and external bil- let fuel rails (-6 AN fittings)
  • Separately mounted ECU
  • Hand-held calibration module
  • Wideband O2 sensor
  • Fuel system included with Master Kit system (includes fuel pump, filter, lines, and fittings)
  • Horsepower level up to 600 hp, dual-quad option supports over 1,000 hp
  • Price $1,784.95 for Base Kit, $2,180.15 for Master Kit Holley Avenger EFI

Holley Avenger EFI

The folks at Holley have been designing fuel distribution systems for engines of all types for over 100 years. Holley's carburetors have been OE at one point or another on many factory performance Mustangs and even sat under the air cleaners of early Fox Mustang GTs (with five-speeds). Holley's foray into EFI has been a long-travelled road and not something they just decided to jump into as a "me too" business. Holley's latest EFI products feature a more traditional "TBI" style throttle body with injectors directly over the throttle plates, just like the OEs used to do it. The Holley Avenger EFI systems are direct replacement EFI units for carbureted intakes, of course, and as such bolt right on to a standard 4150 flange. Holley offers three different throttle body kits depending upon your engine's horsepower level and the kits are surprisingly complete. No laptop is needed either, as the hand-held full color tuner allows for quick and easy setup, and the self-learning ECU combined with the included wideband O2 sensor means no tuning knowledge is required to be up and running in no time.

System Specs:

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  • 700- and 900-cfm cast throttle body assemblies; 700-cfm comes with 65 lb/hr injectors and the 900- cfm can be had with 75 or 85 lb/ hr injectors
  • All kits include injectors, wiring harness, separately mounted ECU, hand-held tuner, wideband O2 sensor, and fuel pump and filter kit
  • Self learning fuel strategy and cus- tom tuning available via hand-held tuner
  • Avenger ECU can be used to con- trol ignition timing with appropri- ate wiring connectors
  • Fuel line (steel and rubber) for return line must be provided by installer
  • Avenger ECU can be upgraded to HP ECU with programmable out- puts for use with power adders like a supercharger or turbo
  • 700-cfm kit good to 400 hp, 900- cfm kits handle up to 525 and 600 hp respectively
  • Price $2,054

MSD Atomic EFI

MSD, known the world over as the "go to" ignition component company for street and racing products, has added another tab to their business portfolio with the much celebrated Atomic EFI system. Who better to put together an EFI system than an ignition products company, right? For combustion you need spark, fuel, and air; and while MSD doesn't provide the air (last time we checked that's still one of the free things in life), now you can configure your ignition and fuel needs from the same company with the knowledge that the parts will work hand in hand with each other. MSD's Atomic EFI mounts to the standard 4150 carb flange like the other bolt-on units in this roundup, but that's pretty much where the similarities end. The MSD engineers designed their EFI as a pulse width modulated system. PWM means the fuel pump's voltage is controlled by the ECU, which in turn controls the pump's pressure/volume characteristics. This is the basis of many OE "returnless" fuel systems. However, if you already have a full fuel system with pressure and return lines rated for EFI, the Atomic unit can easily run at a fixed fuel pressure as well via the hand-held controller and the addition of a fuel pressure regulator. Furthermore, the actual design of the Atomic throttle body is very "carb like" for a retro look and includes the ECU built into the side of the throttle body. You'll even notice what looks like annular boosters; however, these are actually very carefully designed injector nozzles that help spread out the fuel, helping to make more consistent high rpm horsepower.

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System Specs:

  • 1,000-cfm cast throttle body with four 80-lb/hr fuel injectors and integral ECU
  • Wideband O2 sensor with weld-in threaded fitting
  • PWM returnless fuel system stan- dard in Master Kit, including fuel pump, fuel line, and filter handles up to 525 horsepower (at the crank)
  • External power module connects via CAN-Bus technology and fea- tures two electric fan outputs, A/C idle "kick up", and more
  • High Horsepower Fuel Kit increases horsepower capability to 620
  • Retail Price $1,990 -$2,290

Professional Products Powerjection III

Of all the 4150-flange bolt-on EFI units we've discussed here, probably the most carburetor-like unit (visually speaking) is the Powerjection III unit. The four fuel injectors are covered by simulated fuel bowls and the unit uses a dual-feed inlet line assembly, plus all electronics are built into the unit so there are no external modules, ECUs, etc. needed that stand out and yell "EFI" to those checking out your engine bay. Like other systems here, the Powerjection III utilizes a wideband O2 sensor to allow on-the-fly fuel system adjustments while driving. The Powerjection III doesn't technically require a laptop, as it is a self-tuning design, but the unit does supply a software CD and a single wire USB adapter for laptop tuning use. The software allows for fuel mapping, idle control, and other functions at the stroke of a keyboard if you so desire to deviate from the self-tuning feature. While the original Powerjection III required a return line (it was stealthily routed from the bottom of the pressure regulator and owners usually ran the line down the rear of the engine), Professional Products now offers their FuelOnDemand fuel pump controller, which works with carbureted (using an electric pump, of course), return-style, and returnless-style fuel systems. Professional Products offers the FuelOnDemand as a separate product for just about any fuel system or in a Powerjection III offering as a complete returnless EFI solution.

System Specs:

  • 750-cfm cast throttle body with 62- lb/hr fuel injectors and integral ECU
  • Wideband O2 sensor with clamp- on "no weld" bung
  • Does not control ignition but will work with everything from points to CD ignition boxes
  • Complete Kit includes fuel pump, fuel filter, dual-feed fuel inlet, fuel pressure regulator, fuel pressure gauge and fittings; however you must supply your own -6 AN hose
  • Basic Kit is for cars that already have pressure and return lines, fuel pressure regulator, and fuel pump installed
  • Optional hose and fitting kit available to connect Complete Kit components
  • Supports up to 550 horsepower
  • FuelOnDemand fuel pump controler available separately or as part of Powerjection III returnless kits
  • Price $1,682.95-$2,104.95

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