The Best Jeep Engines Ever Produced
Did Your Favorite Jeep Engine Make The Cut?
Updated March 26, 2018
Jeep engines have been powering off-road dreams for more than 60 years. Who hasn’t thought about crashing through the underbrush and throwing mud in a Jeep? Many Jeep engines have come and gone over the years; some good, others trash. Today, we want to take a look at the history of Jeep and several of the For the 2007 through 2011 model years, the Jeep JK Wrangler was powered by the 3.8L EGH V6. These Jeep engines are a bored out version of the 3.3L V6. The bore is 3.78 inches (96 mm) and stroke is 3.43 inches (87 mm), creating a 3,778 cc (231 cu.in.) powerplant. Output varied over the production life of the engine, but the last engines built are capable of 215 hp and 245 lb-ft of torque. This engine is tougher than buyers expected when it was first introduced. Its great torque curve makes it perfect for off-roading. The only reason that Jeep went away from this engine was to meet government regulations for efficiency. The 3.6L V6 that replaced it just isn’t as good, though. Well, there you have it, our list of the best Jeep engines ever produced. We are sure that you have a few more in mind. Feel free to add your favorite in the comments section. Maybe you will find it has a fan following.”Jeep engines that have become legendary. Read on to find the best Jeep engines ever produced.
History of the Jeep
As with many innovations, Jeeps came into existence because of a war. The United States War Department knew by the late 1930s that it may eventually become embroiled in a war in Europe. Knowing that made the Army feel an urgent need for an updated fleet of light battlefield vehicles. To that end, the War Department developed a set of specs and submitted them to 135 U.S. automotive manufacturers on July 11, 1940. Manufacturers were given 11 days to submit bids, 49 days to build their first prototype, and 75 days to have 70 test vehicles built. On top of such a short turnaround, the specs were pretty daunting. They included: 4WD, seating for at least three, a wheelbase of 75 inches (later upped to 80 inches), have a fold-down windshield, a payload capacity of 660 lbs, the engine had to be capable 85 lb-ft of torque, and the vehicle had to have a dry weight of less than 1,300 lbs. The Army found that the weight limit was unattainable, so raised it to 2,160 lbs.
Only three manufacturers were able to develop a bid for the vehicle in time for the deadline. American Bantam Car Company and Willys-Overland Motors made the 11 day deadline for bids. Ford Motor Company was allowed to submit late, rounding out the threesome. American Bantam won the bid because it was able to commit to building a prototype within 49 days, but could not build Jeeps on the scale the Army needed. That opened the door for Willys and Ford to be allowed to submit their prototypes late. After much testing and having bought 1,500 copies from each manufacturer, the Army awarded the end contract to Willys-Overland, mainly because of its strong engine. Basically, the entire history of the Jeep was determined by how strong the first Jeep engines were. That brings us to the first entry on our list of the best Jeep engines, the L134 Go Devil.
The first Willys Jeeps (the MB) were not available to the public. However, by 1945 Willys was able to switch production from military applications to civilian vehicles again. The first civilian model was the Civilian Jeep (CJ). Semantics being semantics, the first units made available to the general public were the CJ-2A. It was powered by the L134 Go Devil engine.
The Go Devil had a displacement just over 134 cu in and had an L-head (valves parallel to cylinders) design – hence the L134 designation. The version in the CJ-2A had a bore of 3.125 inches (79.4 mm) and a stroke of 4.375 inches (111.1 mm). Willys used an undersquare engine so that peak torque would be available at lower rpm. By today’s standards, output was low at 60 hp and 105 lb-ft of torque, but that was pretty impressive in 1945. The best feature of the CJ-2A was its durability. If the Army could torture it on the battlefield, imagine how tough this engine was.
In 1965, Kaiser Jeep, the successor of Willys-Overland, sourced a 327 V8 from American Motors Corporation. To be clear, AMC built this 327 five years before Chevrolet built its more famous 327. Nicknamed the ”Vigilante” by Kaiser-Jeep, this engine was essentially a bored out version of the 287 engine that had been powering the AMC Rambler since 1961. The bore was increased to 4.0 inches (102 mm) and the engine was equipped with hydraulic valve lifters. These Jeep engines were used in the Jeep Wagoneer and Gladiator pick-up truck between 1965 and 1967.
The Dauntless 350 was built by Buick and was used in the Jeep Gladiator and Jeep Wagoneer from 1968 through 1971. Buick 350’s were built differently than other GM 350’s of the era. Buick versions used a deep-skirt cast iron block, an external oil pump, a forward-mounted distributor, and were undersquare. The oil pump mechanisms of these Jeep engines were housed in an integrated aluminum timing cover, so the oil filter was exposed for added cooling. These engines were highly prized for their durability and power and were often modified for hotrods of the era.
We are still stuck in the 70’s with this next engine. The AMC 401 is probably one of the better-known Jeep engines and can still be found conquering many roads and mud trails today. The AMC 401 can be found in some 1971-1979 Jeep Wagoneers, Cherokees, J-10’s, and J-20’s. It has a displacement of 401.11 cu in and in 1971, a stock engine was capable of 330 hp. That number, however, was dialed back to meet emissions and fuel efficiency regulations from 1972 on. The AMC 401 uses a forged steel crankshaft and connecting rods for added durability. These engines are fairly rare because emission controls, insurance rates, and high gasoline prices at the time caused AMC to limit the models that were equipped with the 401. The rarity of the engine combined with its toughness and excellent power output means that these Jeep engines are highly sought after.
Fast forward to the 1987 model year and we come to the inline 6 cylinder AMC 4.0L. These Jeep engines can be found in late model YJ’s and TJ Wranglers, Comanches, Cherokees, and early Grand Cherokees. The first AMC 4.0L has a bore of 3.875 in (98.4 mm) and a stroke of 3.414 in (86.7 mm), so it has a displacement of 241.6 cu in. It has an output of 190 hp and 220 lb-ft of torque. The torque is available at lower rpms, making this a great engine for off-road antics. The AMC 4.0L was held over after Chrysler bought the Jeep line from AMC.
The 4.0L engine is likely the best known of all the Jeep engines ever produced. By the time it was discontinued in 2006 more than 7 million units had been sold worldwide and many owners have reported driving more than 300,000 miles without having to rebuild their 4.0L Jeep engines.
In the late 80s and through the 90s, Jeep went through a phase where the company wanted to attract more daily drivers to the Wrangler line. The automaker attempted to do this by adding fuel efficiency and comfort. Fuel efficiency was tackled by offering a 2.5L inline four-cylinder engine in the YJ and early base TJ Wranglers. This engine can also be found in some Cherokees and Comanches as well. At the end of production, this engine was capable of 130 hp and 150 lb-ft of torque. Like many Jeep engines, the 2.5L surprised people with its long-term durability and low-end power. There are a few people who have trashed it because it is a four-cylinder engine, but it seems they have forgotten that the first Jeeps were all powered by four-cylinder engines.
For the 2007 through 2011 model years, the Jeep JK Wrangler was powered by the 3.8L EGH V6. These Jeep engines are a bored out version of the 3.3L V6. The bore is 3.78 inches (96 mm) and stroke is 3.43 inches (87 mm), creating a 3,778 cc (231 cu in) powerplant. Output varied over the production life of the engine, but the last engines built were capable of 215 hp and 245 lb-ft of torque. This engine is tougher than buyers expected when it was first introduced. Its great torque curve makes it perfect for off-roading. The only reason that Jeep went away from this engine was to meet government regulations for efficiency. The 3.6L V6 that replaced it just isn’t as good, though.
Well, there you have it, our list of the best Jeep engines ever produced. We are sure that you have a few more in mind. Feel free to add your favorite in the comments section. Maybe you will find it has a fan following.
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