Best Jeep JL Engine Swaps

Best Jeep JL Engine Swaps

Last Updated October 7, 2019 | Meghan Drummond
Contents

Even before the JL Wrangler was out in the wild, people wondered why there still wasn’t a V8 option for Jeep. Though the Wrangler’s predecessor, the Jeep CJ, sported a V8, there hasn’t been a single Wrangler with a V8.

The thing you can count on with the Jeep community is that they’re not afraid to make their own solutions, and JL engine swaps started almost as soon as the first of the new Wranglers rolled off of the line. Though it’s tempting to run out and find the biggest and most powerful engine available and figure a way to coerce it into the Wrangler’s engine bay, there are practical concerns related to space, transmission capabilities, and engine compatibility to consider.

Diagram showing all of the underhood components for the JL Wrangler

Stock JL Wrangler

The JL Wrangler has several stock engine options, which serve as a good basis of comparison for engine swaps.

The JL Wrangler’s default engine option is a 3.6L V6 Pentastar that produces 285 hp and 260 lb-ft torque. It gets an EPA estimated combined 18 mpg (17 mpg city and 21 highway), which is nothing to write home about but is perfectly respectable for an off-roader. Though the displacement and cylinder count is the same as the Pentastar that came in the JK Wrangler, the Pentastar in the JL Wrangler has some differences.

By using torque activated cam phasers, Chrysler was able to make this V6 particularly petite without compromising on power. Despite using a dual overhead cam (DOHC) setup, this Pentastar is as lean as many single overhead cam (SOHC) engines.

The other engine option that’s new for the JL Wrangler is a 2.0L turbocharged engine, nicknamed Hurricane, that’s capable of 270 hp and 295 lb-ft of torque.

A small engine that’s labeled Jeep
The 3.6L Pentastar

Transmissions

Either engine option can come with an eight-speed automatic transmission. The eight-speed automatic is a Chrysler made variant of the 8HP50. This is the third generation of these transmissions, which are primarily used in BMWs, Alfa Romeos, and Rolls Royces. It has a max torque rating of 500 lb-ft.

The manual transmission is an Aisin D478, and it is only paired with the Pentastar engine. The Aisin is a great transmission that’s getting rave reviews for its shorter throws and notchy feel. This is a new transmission, but it would appear that the closest transmission on the manufacturer’s website is given with a torque rating of 345 lb-ft. This is an important factor to keep in mind as you look at engine swap possibilities since increasing the engine’s torque significantly may require a transmission upgrade as well.

Your driveline’s capacity should match the power output of your engine, and increasing power significantly may necessitate additional equipment upgrades.

Good Engine Swaps

Though we’re reviewing some of the top candidates for engine swaps, it would be impossible to cover every engine that exists. If you’re debating an engine swap that isn’t on our list, these are some of the criteria we used to think about what engines would be great swap candidates.

When looking at potential engine swap candidates, one of the first things to consider is the physical dimensions of the engine. The Pentastar is roughly 19.8 inches long. Finding a similarly sized engine allows for an easier swap.

Like-brands also tend to have an easier time with engine swaps. It’s easier to Coyote-swap Mustangs for example because it involves putting a Ford motor into a Ford vehicle. All the brand quirks are going to line up to create a better experience with greater compatibility. It’s also easier to get the engine to "talk" to the rest of the vehicle.

The HEMI swap is actually so good, that we’re doing our own here at CJs. Check out this video from CJ’s Off-Road to see how to get a HEMI swap started, and why we think it’s one of the best engine swaps available.

It’s not news to any car enthusiast that cars are essentially built like computers these days, and it’s essential to get the engine to “speak” to the other vehicle components in order to optimize aspects like fuel injection.

There are plenty of Jeep enthusiasts who say they’ve had success swapping vintage small-block Ford and Chevy V8s into their JLs.

Listed below are some of the most popular engine swaps and how practical they are for the JL Wrangler.

JL Engine Swap Specs Comparison
EngineHorsepowerTorqueConfigurationValvesCompression RatioBore x StrokeBrand Compatibility Ease
3.6L V6 Pentastar 285 hp 260 lb-ft DOHC 24 Valves 10.2:1 96 mm x 83 mm Stock
2.0L Turbo I4 "Hurricane" 270 hp 295 lb-ft DOHC 16 Valves 10:1 84 mm x 90 mm Stock
3.9L Cummins 4BT 105 hp 265 lb-ft OHV 8 Valves 17.5:1 102 mm x 120mm No
6.2L Hellcat 717 hp 656 lb-ft OHV 16 Valves 9.5:1 104 mm x 91 mm Yes
5.0L Coyote 360 hp 380 lb-ft DOHC 32 Valves 10.5:1 92.2 mm x 92.7 mm No
1992 HO 5.0L Windsor 220 hp 300 lb-ft OHV 16 Valves 9.5:1 101.6 mm x 76.2 mm No
6.2L LS3 430 hp 425 lb-ft OHV 16 Valves 10.7:1 103.25 mm x 92 mm No
5.7L Hemi 395 hp 410 lb-ft 16 Valves OHV 10.5:1 99.49 mm x 90.88 mm Yes

Jeep Wrangler Diesel Swap

Diesel swaps are hotly debated and advocated for and against on just about every forum. One of the diesel options that’s recommended frequently is the 3.9L Cummins. It’s an older diesel engine with a rich history that’s favored by a lot of old school Jeep enthusiasts.

The Cummins is pretty solidly an off-road engine choice. It shakes and rattles like only a diesel can, and puffs up some emissions-heavy fumes. The deep rumbly sound is right at home off-road, but in the middle of the suburbs seems out of place.

You just have to ask “why” though.

It’s not easy to do any engine swap, and most people only are interested if there are substantive performance gains, but in the case of the Cummins, you actually lose power.

The 3.9L Cummins is 30-inches long, barely small enough to fit into the engine compartment, and after all of that work, you get an engine that’s capable of 105 hp and 265 lb-ft of torque. Less than the stock engine. It’s a relatively time-consuming downgrade, but it’s definitely possible.

If you really love the smell of diesel, you can just wait until later this year when Jeep is unveiling a stock 3.0L V6 turbodiesel option.

JL Hellcat Swap

Hellcat JL and JT swaps are getting a lot of publicity recently, and it certainly seems to make sense. It’s another Dodge product, and one of the best V8s currently on the market, capable of getting 717 hp and 656 lb-ft. But it’s also a sizeable engine.

The Dodge family of engines
Dodge Engines

Kuniskis, the boss of Jeep North America, said, “It fits like a glove, but the problem is that it fits like a glove there is no air space around the engine.”

The lack of air space has several effects, none of them good. The most obvious is that in the event of a crash, there’s no crush space, making the Wrangler a substantially more dangerous ride. The other disadvantage is that without any air space around the engine, airflow is compromised and there’s no space to add features like a cold air intake to offset the loss. The engine bay is quickly going to be filled with hot air, meaning that Hellcat isn’t going to function anywhere near as well as it would in a Challenger.

It’s a lot of money, time, and energy spent on a vehicle that’s not going to be as powerful as it could be and will still fail every safety, emissions, and fuel economy test.

Coyote Swapping a JL Wrangler

Some Coyote engines will not fit, but a few, like the ones from the F-150, will. But much like the Hellcat, it doesn’t leave room for a whole lot else. Assuming you go with the F-150 Coyote, you’ll see about 360 hp and 380 lb-ft of torque.

That means that doing a Coyote swap into a Wrangler will bring you all of the headache of a Hellcat swap without even offering the comfort of a Mopar to Mopar compatibility. We understand why people like the idea of this one, the Coyote is a great engine, and it puts out a ton of power, but ultimately this is a bad-idea-swap.

Four Ford engines displayed
Ford Engines

Ford Windsor Swaps

The Windsor engine was around for decades because of its reliability. These engines, and other small block Ford V8s, are easy to find, and easy to work on, making them popular for engine swaps. Because they are an overhead-valve style, they tend to be relatively small compared to modern engines.

Unfortunately, because these small blocks haven’t been made for many years now, the ones that are around tend to have a fair amount of wear and tear on them. Engine technology also wasn’t as advanced as it is now, which means that there isn’t a lot of support for modern developments in the Windsor. It’s also a Ford engine that you’re trying to get to communicate with a Jeep.

Depending on which Windsor you’re considering, the horsepower could range from 150-235 hp, and you may be able to get a 300 lb-ft torque model. It’s not a lot of gain, and it’s in the form of an older engine that will most likely have issues sooner rather than later.

Close view of a DOHC and OHV engine
The Coyote is a DOHC while the Windsor is a pushrod

LS3 Jeep Wrangler Swaps

LS engines are some of the last remaining pushrod, or overhead valve, engines. These engines are smaller-sized relative to overhead cam engines of similar displacement size. This means that you can fit more displacement into a smaller space, like say, inside of your JL Wrangler.

The advantages to using an LS3 are obvious. You gain a lot of power in the form of an easily obtained crate engine with substantial aftermarket support. The 6.2L LS3 engine has 430 hp and 425 lb-ft of torque, which is a lot more than the stock engine.

The disadvantages, of course, are numerous. You’re using a Chevy engine inside of a Jeep product, which is a little bit like trying to mix oil and water. There are some conversion shops that have figured out a way to do it, and they do a great job of it, but it’s not the easiest Jeep engine swap.

Hemi-Swapped Wrangler

This is a JL engine swap so good we’re surprised more people aren’t excited about it. Every aspect of it makes sense. It’s about as large a V8 as you’re going to be able to comfortably fit into a JL, with a massive displacement.

The 5.7L Hemis are actually relatively affordable, making it a good budget engine swap. And it’s another Mopar product. Swapping within a brand family always makes the swap a little bit easier, and that’s especially true here.

In short, it’s an affordable, powerful engine with a great hemi sound that should pair well with the other elements of the JL Wrangler.

Three engines side by side on stands, showing very different sizes
Engine swaps come in a variety of sizes

If you’re looking for a little extra power but aren’t ready to commit to a full engine swap, getting a supercharger for your Wrangler offers a lot of horsepower gains for relatively little work.

Source: The Drive, Engine Labs, Car and Driver, Jeep, Allpar, Cummins Hub, F-150 Hub | Image Credit: Dodge, Ford, RX7 Club, Engine Labs

Best Jeep JL Engine Swaps

If you’re thinking about getting a new engine for your JL Wrangler, there are a lot of options. Here are some of the top engine swap candidates and the pros and cons of each, as well as engine spec comparisons.

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