Modern Engine Swaps into an Early Bronco

If you want to swap in a complete engine and transmission EFI fuel injection setup and don’t want to break the bank, then a 1989-1993 Ford 5.0L HO motor is a great option. The 1989-1993 Ford 5.0L HO motors are full roller motors (roller cam and lifters plus roller tipped rockers) and have mass air sensors (determines the mass flow rate of air entering the engine). From the factory the Ford 5.0 HO had 220 horse power. With a cam swap, valve springs and better air intake you can easily gain about 40 horsepower on top of that. Some modifications such as new heads or stroker kits, larger injectors, etc. will require the computer to be reprogrammed to the new parameters. One advantage of the Ford 5.0L HO motors is that they have the same motor mount location and bell housing bolt pattern as the factory 289 & 302 V8 engines found on early Broncos. However, they are 50 oz externally balanced unlike the pre-80’s 302 that was 28 oz externally balanced. This means you will need the correct 50oz harmonic balancer and 50 oz flywheel for manual applications or 50 oz flex plate for automatic applications. These motors can be found in Ford Mustangs and often come with an AOD transmission as well. When sourcing this power plant you want to get the entire engine along with the ECU/ECM (computer). The serpentine setup that comes factory on these motors will not work with a mechanical fan and in most situations it is easiest to swap out the serpentine setup for a factory v-belt drive unit using the following part numbers:

• #6482 Harmonic Balancer
• #6525 timing chain cover
• #6486 water pump
• #6488 dual groove crankshaft pulley
• #6484 dual groove water pump pulley

By swapping to this setup you are able to retain your standard radiator as opposed to converting to a reverse outlet radiator which is required with the factory 5.0 water pump. O2 sensors will once again be required for this setup. You will also need a high pressure fuel pump and a fuel tank with a provision for return line. Our #6199 EFI 23 gallon Fuel Tank works great. For the wiring, TOMS OFFROAD offers a complete plug and play 5.0 EFI wiring harness #6138. This 5.0 EFI Fuel Injection Wiring Harness is high quality and easily installed in your early Bronco. Designed to work with 89-93 Ford Mustang 5.0L EFI motors with mass air-flow, simply lay this kit over the engine and connect the wires. This harness will also work with 86-89 speed density Mustang engines. To run this EFI wiring harness on a 1986-89 speed density Ford 5.0L engine, you will need to ensure the MAP sensor is hooked up to vacuum and ignore the MAF sensor (it can be used for a future upgrade). This engine wiring harness is designed for engines that have the throttle body coming out on the passenger side of the upper plenum. A single connection into a power wire from the main wiring harness and it is done. If you are a skilled individual, you can strip the factory harness that comes with the Ford 5.0L motor and remove all unnecessary wires and re-loom the harness to save some money. 86-89 Ford 5.0L engines can be used, but they are slightly less desirable than the 89-93 version because they may not be roller motors and the speed density unit is not as efficient as mass air. For Bronco hood clearance, a car style 5.0L is necessary. Truck engine models have a much taller intake and will not fit without hood scoops and/or a 3″ body lift.

Another common swap is the late 90’s to early 2000’s Ford Explorer 5.0L engine. This is a desirable swap because you are able to use the factory serpentine set up. The Explorer motor is a very similar swap to the early 90’s Ford 5.0L with a few exceptions. Depending on the year, the Explorer motor can have GT40 or GT40P heads. The GT40P heads can lead to issues when purchasing headers due to the spark plug orientation. GT40 heads are great factory heads with good flow and increase the horsepower rating as compared to earlier Ford 5.0L engines. The Explorer motors vary year to year on wiring. Some are coil pack while others are standard coil. Also the mid-year 1999 and newer motors have a returnless fuel system. When purchasing a stand alone harness for this swap Ron Francis Wiring will build a harness for your specific application if you give them the specs on the motor you are planning on using. Later model Ford Explorer motors have an ECM/ECU that can be locked when pulled from vehicle and will need to be flashed, as of the date of this article Ron Francis does this as well. You would need a reverse outlet radiator to match the reverse rotation water pump. This engine also has the same motor mount location and bell housing configuration as factory making installation easier. However this is a 50 oz externally balanced engine like the early 90’s 5.0L so you will need the correct 50 oz flywheel for manual applications or 50 oz flex plate for automatic applications. These Ford Explorers usually have a 4R70W transmission that can be controlled by the factory ECU/ECM if the Explorer had an automatic transmission from the factory. This saves some money since a stand alone transmission control is not needed. The main benefit for choosing an Explorer motor over earlier 5.0L engines is the serpentine setup, otherwise the earlier 5.0L is an easier swap.

The final option we will discuss in this article is the new Ford 5.0L Coyote motor. This swap is becoming more popular by the day and is a great high end conversion that offers 420+ horsepower and increases the value of the Bronco exponentially. The early Bronco Coyote engine swap is considerably more expensive than the previous options but gives you a complete new powertrain. When doing a Coyote swap in your 66-77 Ford Bronco, expect to pay between $10k to $15k on parts alone at a minimum. This swap is also considerably more labor intensive. You can source a 2011-present Coyote 5.0L motor used or buy a new crate Coyote 5.0L engine from Ford Racing. You will also need a lot of parts from TOMS OFFROAD including custom motor mounts, headers, front drive bracket, miscellaneous bolt kits, powers steering spacer plate, O2 sensors, high pressure fuel system and more. Ford Racing sells a control pack for specific year breaks of the Coyote motor that is a stand alone harness for the engine. The Coyote 5.0 has a modular bell housing bolt pattern so a 4R70W or 6R80 automatic transmission are the most commonly used transmissions in these swaps. Either transmission requires a stand alone transmission controller. This swap seems to be the wave of the future but anyone looking to approach this conversion should take into consideration the costs and time involved before attempting it.

Any of these swaps are a great upgrade for your tired old early Ford Bronco power plant. Which is best for you really depends on what you are trying to achieve in your build. We recommend determining your end goal with this swap, how much labor you are okay with doing and what you believe you are capable of tackling. Once you have decided on an engine swap for your early Bronco, make a parts list with prices to determine if the final cost is within your budget. With any swap there are typically miscellaneous expenses that can arise, so be sure to include some miscellaneous extra in your budget calculation ($500 is generally a good number depending on your math and planning skills). With most applications we recommend also upgrading the cooling system at the same time to ensure your new motor is running at optimal temperatures. Also keep in mind that most EFI Motors are slightly taller and may require a body lift under certain circumstances. If you have any further questions please call and talk to one of our knowledgeable technicians.