Jeep has an unusual history when it comes to engines. The brand’s ownership has changed owners more than once than a Honus Wagner baseball card, and in the process it has been subjected to whims and best-laid plans from companies that did not always have the solidest financial footing or engineering resources.
What are the more compelling Jeep power plants that have emerged from this mix of mixed mechanical DNA? Here are our picks for the best Jeep engines of all time.
Willys Go Devil
The original Willys Jeep was built for the US Armed Forces to go anywhere that saw action during World War II. The civilian jeep, or “CJ”, helped popularize off-road driving as a pastime after the war, and a large part of that vehicle’s traction was its combat-tested engine, the four-cylinder Go Devil.
Developed over a five-year period from a low-powered, economy-focused engine to an extremely reliable, torque-happy military-specific engine, the Go Devil produced about 60 hp and 105 lb-ft of torque from its 134 cubic inches of displacement. Go Devil transitioned almost seamlessly to civilian life, where it got an improved cooling system and a softer crankshaft to help it fit better on country roads.
The engine remained in production until 1952, when the Willys Hurricane took over – no, not the two-turbo inline six that is under the hood of the new Jeep Grand Wagoneer, but the original four- and six-cylinder plates, which gave a real increase in power compared to the original Go Devil design thanks to their improved breathability and higher compression ratio.
The largest V8 ever equipped for any Jeep model was the AMC 401. The ultimate edition of American Motor’s eight-cylinder architecture, the 401 was offered in a number of different shapes (including the Javelin muscle car) alongside its use in the full-size Jeep ( Wagoneer, Cherokee and J-Series pickups).
The 401 cubic inch engine represented the third generation V8 built by AMC, developed from the 390 CID that had never made it into a Jeep, and with forged rods and a forged crankshaft. The power ranged from 330 horses to less than 200 ponies by the end of the 1970s after emission equipment had suffocated the engine from its heyday. The torque reached a peak of just over 400 lb-ft. Like most great engines of the era, the 401 ended up under the hood of Jeep’s largest SUV, as rising fuel costs had driven it completely out of the 1977 passenger car mix.
Of all the Jeep engines in the world, the 4.0L inline six-cylinder is by far the best known. One of the last engines developed by AMC, it debuted in 1986 as the most powerful option available from the XJ generation Cherokee, and it remained in the Jeep series through not one, not two, but three changes in business ownership. for the next 20 years of Jeep’s history.
What about Jeep 4.0 that has made it so popular with both owners and enthusiasts?
In a word: reliability. The 4.0 I6 has a reputation as an immortal engine, an engine that withstands huge amounts of abuse (and mileage) and keeps ticking. In the early 1990s, the engine was good for a respectable 190 hp (in High Output trim), and it had spread across the entire range to be available in the larger Grand Cherokee, Comanche pickup and the iconic Wrangler.
3.6L Pentastar V6
After the disappearance of the 4.0, Jeep’s six-cylinder fortunes went out for a few years when the parent company Chrysler tried to close the gap with the worker-like, but ultimately uninspiring V6 that was originally offered with the brand’s minivan. In 2012, however, a new bright spot appeared on the horizon in the form of the Chrysler 3.6L Pentastar V6.
Let’s be clear: Pentastar is not an “exciting” engine. With that said, with 285 hp and 260 lb-ft of torque on the crane, it provided a huge upgrade over the engine it replaced, with a fuel mileage bonus to match. One of the last pieces of the modernization puzzle that the JK generation Wrangler had tried to put together, Pentastar was also offered as an entry-level engine for the Grand Cherokee (with a smaller displacement edition found in the compact Cherokee).
3.0L Turbodiesel V6
Jeep was one of the first domestic SUV builders to use diesel, starting with a common rail engine in the late 2000s. By the middle of the following decade, it had significantly improved its turbodiesel range thanks to Fiat-Chrysler’s ties to Italian engine builder VM Motori.
The result was the 3.0L ‘EcoDiesel’, an engine that could be used with the Grand Cherokee (and much later the Wrangler and Gladiator). With 240 hp and 420 lb-ft of torque, the turbodiesel unit could drive 30 miles per gallon, which represented a big step up in efficiency for Jeep’s larger options without any real significant reduction in performance. No other American sports vehicle of similar size has been able to match that level of thrift and muscle.