Swapping Modern Power Plants in Early Bronco

One of the most common questions we receive at Tom’s Bronco Parts is, “What are some of my options for modern power plants, and what parts do I need when doing these swaps.” To give the customer the best answer suited for their situation, we always start by seeing what they are working with at the time and what they are hoping to achieve when the project is finished. Below we have given you multiple scenarios and some recommendations as well.

Lets start with the guy who has rebuilt his motor or has a strong running engine, but would really prefer to have EFI (electronic fuel injection) and is looking for the easiest way to achieve this. In this instance, we would recommend an aftermarket throttle body injection kit such as the Fitech units we offer. The FiTech GoEFI 4 fuel injection system is the ideal throttle body style fuel injection conversion for your Early Bronco. This EFI kit will bolt in place of your carburetor for a simple fuel injection conversion. You will need to install new fuel lines, as the Fitech requires a return line for the unused fuel, and a high pressure fuel pump as well. The best way to achieve this is by adding a TBP high capacity 23 gallon tank for EFI conversions #6199 which includes an in-tank fuel pump assembly. The GoEFI 4 600HP EFI supports 289, 302 or 351W engines from 250 HP to 600 HP. The Fitech units come in bright anodized or black and has a color hand-held tuner module. It is self learning and supports timing control (with 2 wire alternator setups). Wide band O2 sensors need to be added to the exhaust system so the Fitech can read how much O2 remains in the exhaust as it exits the engine. This can be done by welding O2 bungs into your exhaust manifolds, headers or exhaust pipes. It is best to install the O2 sensors as close to the collector point as practical in order to get the most accurate readings. Monitoring O2 levels in the exhaust is a way of gauging the fuel/air mixture. It tells the computer if the fuel mixture is burning rich (less oxygen) or lean (more oxygen).

If you are wanting to swap in a complete power plant with OEM EFI and don’t want to break the bank, then a 1989-1993 5.0 HO motor is a great option. The 1989-1993 5.0 HO motors are full roller motors (roller cam and lifters plus roller tipped rockers) and have mass air (determines the mass flow rate of air entering the engine). From the factory the 5.0 HO had 220 horse power but with cam swap, valve springs and better air intake you easily gain about 40 horsepower. More mods such as heads or stroker kits, larger injectors, etc will require the computer to be reprogrammed to the new parameters. These motors have the same motor mount location and bell housing bolt pattern as the factory 289 & 302 V8 engines found on early Broncos, but 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 #4067 or 50 oz flex plate for automatic applications #4050B. These motors can be found in Mustangs and often come with an AOD transmission as well (please look for future article on transmission swaps). 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 and #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, Tom’s Bronco Parts 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 5.0 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 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 5.0 and remove all unnecessary wires and re-loom the harness to save some money. 86-89 Ford 5.0’s 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 5.0 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 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 5.0 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 location. GT40 heads are great factory heads with good flow and increase the horsepower rating as compared to earlier 5.0 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 return-less 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 planing on using. Later 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 #6372 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 #4067 or 50 oz flex plate for automatic applications #4050B. These Explorers usually have a 4R70W transmission (please look for future article on transmission swaps) that can be controlled by the factory ECU/ECM if the Explorer had 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 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. This swap is considerably more expensive than the previous options but gives you a complete new power train. When doing this swap expect to pay between $10k to $15k on parts alone. This swap is also considerably more labor intensive. You can source a 2011-present motor used or buy one brand new from Ford Racing. You will also need a lot of parts we offer at TBP including custom motor mounts, headers, front drive bracket, misc bolt kits, powers steering spacer plate, O2 sensors, high pressure fuel system. 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 has a modular bell housing bolt pattern so a 4R70W or 6R80 automatic transmission are the most commonly used transmissions in these swaps. Either requires a stand alone transmission controller (please look for future article on transmission swaps). 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 power plant and it really depends on what you are trying to achieve in your build which is best for you. We recommend determining what you want to achieve with this swap, figure out how much labor you plan on doing and what you believe you are capable of tackling. Then 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 for this just in case). 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 most EFI Motors are slighly taller and it is not requiered but recomended to install at least 1″ body lift.  If you have any further questions please call and talk to one of our knowledgeable technicians.