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10 Uncommonly Common Off-Road Engines

Building a 4x4 then power it with one of these.

One of the most unique things about the off-road world of custom-built 4x4s is this: When you come across a really cool build and pop the hood, more often than not you'll find the engine that's powering it isn't the same one that vehicle left the factory with. We've seen diesels in Ford Broncos, Chevy engines in Range Rovers, Range Rover engines in Jeeps, Oldsmobile engines in Chevys, Cadillac engines in GMCs, and any host of other non-original powerplants. You can look for some sort of rhyme or reason: Perhaps one engine is better than the other off-road, and perhaps one has inherently more low-end torque than the other, more durability, or more power. But all that aside, after decades of close study we chalk it up to nothing more than the simple fact that people who enjoy off-roading at an elite level are independently minded. In the same way they don't want to be shackled by the constraints of a paved road dictating where they can and cannot venture, so too do they not want to be shackled by the limitations of what engine originally powered their choice of vehicle. So to that end, here are some of the more commonly swapped non-original-application engines we come across in cool rigs on the trail.

Small-Block Ford V-8

Small-block Ford engines from early 289s to more modern injected 5.0L HO units from Mustang, Explorer, Thunderbird, and 351Ws in pickups, Broncos, and other Ford vehicles up to the late 1990s are relatively compact, not too heavy, and develop excellent power. Thanks to huge aftermarket support it's really easy to find independent wiring harnesses and engine management systems for Mustang 5.0Ls, and because they were available with factory manual transmissions, the aftermarket makes it super easy to swap behind many auto or manuals in all sorts of vehicles.

Cummins R2.8 Turbo Diesel Crate Engine

With 161 horsepower and 310 lb-ft on the factory tune and plenty of room for aftermarket tweaking, the Cummins R2.8L Turbo Diesel Crate Engine can deliver between 19-30 mpg in your 4x4 while offering a ton of tractive down-low off-idle power and a super easy installation. These crate engines come complete with everything you need to get it running including front accessory drive setup, fuel pump, wiring harness, ECU, and even throttle pedal. Grab a bellhousing or adapter to mate it to your transmission of choice, build your motor mounts, and hook the intake up to an aftermarket intercooler; you're in business.

Cummins 3.9L 4BT

Although not as smooth and refined as the R2.8L, the venerable 3.9L Cummins 4BT has been in service in the U.S. for decades, and as such, is fairly easy to find on the used market. Powering everything from bread and potato chip trucks to farm and construction equipment, these four-cylinder turbodiesel engines are mechanically operated and when intercooled and mildly modified, can be great torque producers that deliver impressive mileage numbers.

Cummins 5.9L 6BT

While much bigger and far heavier than most gas engines, there's no denying the brute twist and storied longevity offered by the all-mechanical versions of the '84-'98 12-valve 5.9L 6BT. Offered in various forms from non-turbo/non-intercooled up to turbocharged intercooled versions, the 5.9L built before the engine went to electronically-controlled 24-valve in 1998.5. And while there's really nothing wrong with the newer 24-valve 5.9L ISB and 6.7L ISB Cummins engines, the newer versions don't hold the same cult following as the mechanically operated 6BT.

GM Gen III/IV/LS V-8

Second only to the venerable '55-'99 small-block Chevy, GM's Gen III/IV/LS engine platform, informally referred to under the general term, "LS" has rivaled almost all others in terms of swapability. With an aftermarket solution for virtually any situation at fingertip's reach, the LS engine makes very generous horsepower, is relatively lightweight, is easy to fit under the hood of most vehicles, and can be cheap and affordable.

GM TPI/TBI Chevy V-8

Once the powerplant of feathered mulletwagons everywhere, the GM TPI engine was a marvel when it was introduced. Kicking the antiquated and dubious "crossfire" injection to the curb, the tuned-for-low/mid-range long-runner TPI engine with separate throttle body and injectors was available in 5.0L and 5.7L performance cars of the mid/late 1980s until the LT1 supplanted it. During the same time period, a more pedestrian but simpler throttle body injection system could be found in sedans, vans, pickups, and SUVs of the era, and it delivered easy start, good power, and long life. Any TBI or TPI Chevy V-8, while not super sexy, will deliver reliable power at all angles for your 4x4.

Buick Odd/Even-Fire V-6

Once offered as a factory engine in Jeeps from 1967-1971, the Buick V-6 is a compact, easy-to-fit, plucky little powerhouse that's eager to work hard. Although the even-fire 3.8L factory-injected versions from the 1980s are rare, it's a slam-dunk to update any even-fire with an aftermarket TBI injection conversion. And we've heard of several successful odd-fire injection conversions using Megasquirt systems, though we've never done one ourselves. The front-mounted distributor doesn't impede firewall clearance and several factory exhaust manifolds and aftermarket header systems are available. Add to that the fact that many factory and conversion bellhousing options are out there, as well as three- and four-speed automatic options and you can see how these little Buick V-6 engines can make a good option for any off-road repower project.

Chrysler/Dodge 5.7L Hemi V-8

With a minimum of 330 horsepower, and up to 395 horsepower in factory form, the 5.7L Hemi from the early 2000s-present can make a great high-rpm powerhouse for your off-road vehicle that with 385-405 lb-ft ratings, doesn't skimp on the torque. Although relatively wide and not as well supported in the aftermarket as the LS engines, with companies like Holley and others stepping up their swap support game, the Hemi is more and more becoming a viable option as a repower consideration.

Dodge 5.2L/5.9L Magnum V-8

With relatively simple MPI injection systems, a bellhousing that can mate to several auto or manual transmissions, and respectable horsepower and torque numbers, the 1992-up Magnum V-8s offered in Dodge pickup, SUV, and vans of the era can make a great repower option for your older 4x4 that won't break the bank. The engine management systems are relatively forgiving and easy to make work by paring down the harness and they respond relatively well to internal hop-ups if more power is required.

GM LX5 3.5L DOHC V-6

OK, these engines aren't nearly as common as any other on this list, and there's virtually little-to-no aftermarket support anymore. But we're including it for no other reason than these little GM engines, affectionately dubbed "Shortstar" in the aftermarket world, share the same 60-degree GM V-6 bellhousing bolt pattern as 2.5L Jeep Wrangler and 2.8L GM S10 vehicles. Able to make about 260hp/260 lb-ft when uncorked of its factory tune and well able to handle moderate boost, these little engines have durable bottom ends and the ability to rev to about 6,500 rpm in factory form. Weighing roughly 300 pounds dressed and wet, as long as you can fit the transverse log-style oil pan behind your front axle or between your IFS Crossmember, these durable little engines are a great way to gain good power without a big weight penalty.