An engine swap is the most frustrating modification you can make to a Jeep: You position the motor too high and you can’t close the hood, too low and the axle makes a window in the oil pan when you hit your first bump, too far back and you’ll end up beating the firewall with everything in your toolbox, too far forward and you can’t fit a proper fan and radiator, too far to the right and the exhaust hits the steering shaft, too far to the left and the starter hits the driveshaft. Most Jeep engine compartments offer very little room for error when swapping in a V-8. And I haven’t even mentioned driveshafts, fueling, cooling, or exhaust routing issues yet.
Some of the more common questions I get involve engine swaps, and rightly so, because most Jeeps didn’t come from the factory with an overabundance of power under the hood. Many Jeeps are downright pathetic once you add bigger tires and more weight in the form of aftermarket bumpers, winches, body armor, and so on. But not every engine swap is a good idea. Just because you have a good engine and tranny doesn’t mean it’s a good candidate for a swap in your Jeep. In engine swapping, boring and common is easier and less expensive—oddball and exotic engine swaps typically require more fabrication, experience, and money.
Don’t ever swap an engine simply to get better fuel economy. The improved fuel mileage of the new drivetrain will never pay for the cost of an engine swap, unless maybe you’re installing an electric motor.
Some readers want to know the exact part numbers they’ll need to make an engine swap. Anyone who’s ever swapped an engine before will tell you it doesn’t work that way. I can’t really answer a question like that because nearly every engine swap is different. Sometimes other previously added aftermarket parts will interfere with the swap, sometimes you have to modify or fabricate components to make the swap complete, and quite often you run into other totally unexpected problems. It’s not like bolting on a bumper. There are several systems that need attention and reworking when doing an engine swap.
Other readers have asked how much an engine swap will cost. Again, this is an impossible question to answer unless you are dealing with a shop that specializes in the exact swap you want to make. The cost will depend on how much you pay for the engine and tranny, who does the labor, and a multitude of other things. Getting your hands on the engine and tranny is actually the easy and often inexpensive part. The things that people generally discount are the additional modifications required when making a swap. The costs for wiring, a proper radiator, exhaust, driveshafts, and so on can add up quickly, sometimes to the tune of two, three, or even four times the cost of the engine itself. So don’t fool yourself into thinking your engine swap will be inexpensive just because you have an engine in your backyard. If you’re working with an older Jeep, the swap will probably cost more than the Jeep is worth. So if the motor you want to swap in was actually an option for your model Jeep (2.5L four-cylinder to 4.0L for example), you’re really better off selling the Jeep and buying one with the engine you want, unless of course you’ve already made a bunch of modifications that can’t be transferred over.
By the time you’re done with your engine swap, you’ll probably have pulled out all your hair because of all the complications. But once it’s actually finished and running, an engine swap is probably the most rewarding modification you can make. Especially when you hammer the throttle for the first time and your V-8 Jeep takes off like a bat outta hell. You’ll be smiling from ear to ear.