Matt Rawlins
May 1, 2000
Contributers: Matt Rawlins, Keith Keplinger Photos By: Keith Keplinger

Step By Step

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Here are some of the necessary parts for this conversion, minus the exhaust system--which you will also need to attain. Pictured here is the electrical EEC harness, EEC computer, mass air tube, throttle cable, and heavy-duty clutch from RAM.
Once all of the necessary cables and wires have been disconnected, the 3.8L engine can be lifted out and laid aside. Although Tim is an experienced technician, he still needs to gather his thoughts and go over the next few steps in his mind, so as not to forget anything.
Tim then begins by removing the V-6 A/C lines, which are different from the V-8's.
Next, Tim unveils the EEC computer, which is located in the passenger-side kick panel. This V-6 computer will need to be taken out, along with the V-6 electrical harness.
Once the wires have been disconnected from the computer, the EEC harness--located in the right fenderwell--can be pulled through and put aside. The new V-8 EEC harness and computer can now be installed and routed the same way as the V-6 harness.
Once the new harness has been routed through the right fenderwell, Tim installed the necessary smog devices, which are a must for V-8s. Since this isn't standard on the 3.8L car, the smog equipment must be attained from a donor 5.0 Mustang. As you can see from this photo, Tim nestled the smog system in the same side fender as the electrical harness.
Now with the V-8 harness in place, the TFI module--which isn't found on the V-6--can be plugged in on the right side of the engine bay.
With the V-6 engine out of the car and the electrical harness routed through, Tim can now go underneath the Mustang and disconnect the exhaust system and the driveshaft. For a swap such as this, you'll also need to obtain a new dual exhaust system from a donor car, or just purchase a new system from any aftermarket company. Also, with the new exhaust, you'll need to get the hangers from a V-8 car or from Ford. Without the hangers, your exhaust pipes won't sit straight, nor will they be secure.
With the driveshaft and exhaust out of the way, Tim lowered the V-6's transmission in order to install the new clutch. The V-6 and V-8 T5 transmissions are almost identical, including the fact that they both have the same gear ratios. The only difference, according to Tim, is the V-8's gearsets are stronger than the V-6's.
According to Tim, the clutch upgrade is a must for performance when it comes to converting your existing 3.8L into a pavement-pounding 5.0L. For this installation, Tim chose to have a RAM heavy-duty clutch, known for its exceptional grip and longevity.
Now that the clutch is in and the tranny reinstalled, the Mustang is lowered and the new 5.0L engine is ready to be dropped in. Note how most of the engine's parts are already installed, including the headers, intake, throttle body, and even the spark plug wires. The more complete the engine is, the easier the entire process will be. Make sure if there is anything that you want changed with the engine, such as spark plugs, wires, headers, and so on, that you take care of it before you drop it in the car. You and your knuckles will be glad you did.
After Tim safely dropped in the 5.0L engine, he began making all the necessary connections from the main electrical harness to all the right sensors and relays. As for the fuel system, the V-6 engine also uses 19-lb/hr injectors, but there are only six of them (obviously) instead of the needed eight for the V-8. The best thing to do is to purchase eight new injectors from Ford (PN M-9593-C302) so you know you're getting a balanced set instead of just two new ones. You also can opt to go with a set of bigger injectors if you plan on modifying the engine later on. As for the rest of the fuel system, Tim assures that the V-6 stock 88-lph fuel pump is adequate for an engine producing up to 300 hp.
One of the differences in parts that you'll definitely need to acquire either from a dealership or a junkyard for this conversion is the throttle cable and linkage. The V-6's cable is considerably shorter than the V-8's, as you can see from this photo.
Next, Tim swaps the new V-8 throttle cable to the V-8 throttle linkage, which is also different from the V-6’s linkage. Once that’s done, Tim removes the cruise control servo from the V-6 engine and places it in the engine bay with the V-8.
The only difference with this is that the cruise control cables are different, which is what he is swapping out in this photo.
With most of the work almost complete, Tim connected the A/C lines, which must be from a V-8 car. The V-6 A/C lines cannot be reused.
One of the last steps in this conversion is to swap out the radiator and cooling fan from the V-6 to the V-8. Although they are not identical, according to Tim, they're extremely similar with the exception of having a different fan speed. That's why you must replace the V-6's fan control module with a V-8's.
This module is located beside the coolant overflow bottle and looks like this. The new V-8 module is the one on the left.
Once all the hoses and connections are double-checked, Tim tightens all the bolts to the front of the car.
The next to the last step requires Tim to reuse the airbox from the V-6 engine, which is identical to the V-8's, except for the air meter and the air tube.
Here is the final product as it looks with everything in the right spot. The new 5.0L engine looks like it was never even out of the car.

There comes a time in every Mustang enthusiast's life when he realizes the power harnessed by the stock motor is nice, but just not enough. We're all guilty of wanting more and more horsepower as time passes. The car we fell in love with, although cool as ever, needs a little help to get us over the horsepower hump. A supercharger, some nitrous, and all of the other regular bolt-ons, seem to do it for most of us. We can go from a 225hp car to 350 screaming ponies in a matter of a few weeks.

Those who unwittingly purchased a V-6 Mustang instead of a V-8 are starting out in a considerable hole. You know who you are, and we're here to try and remedy your mistake. Whether you bought the car new or used, it doesn't matter--you own it now, and you've got to make the best of it. By admitting your mistake, you'll be taking the first step toward more power.

That first step is an engine swap. If you've been pondering the possibilities of swapping your anemic 3.8L V-6 for a potent 5.0L V-8, we're here to show you how. With the help of Ford Racing Performance Parts and the handy work of Tim Matherly of MV Performance out of Statham, Georgia, we'll have your Mustang terrorizing the neighborhood with its new set of lungs in no time. Apart from having the obvious benefit of increased displacement, swapping to a V-8 engine will enable you to take full advantage of the multitude of speed parts designed for injected 5.0s, such as the aforementioned supercharger, nitrous, heads, and other fine goodies.

We compiled all of the necessary parts (see the sidebar The Part Numbers Game) for this conversion, and the following pages will highlight our engine swap, as well as a list of all the parts needed to make this swap possible. Basically, we're giving you a good foundation as to what's involved rather than step-by-step instructions. Whenever you deal with a swap that involves EFI, it requires at least a basic knowledge of Ford electronics. In other words, don't try to do this by yourself over the weekend, and especially with your daily driver. According to Tim, "A project like this isn't the hardest in the world, but you do have to know what you're doing."

Horse Sense: A question that looms over an owner's head as to whether or not to notify his insurance company of the engine change that has taken place. After a call to an insurance company, they said that if you want your new 5.0L engine insured, it's best to 'fess up.