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When most people think “pickup trucks,” they think “V8 engines.” But some of the best truck engines of all time have been inline six-cylinders. In fact, though I’ve owned multiple trucks I’ve never owned a V8 (cue gasps). With the inline six-cylinder making a comeback in modern pickups, as an efficient turbocharged powerplant, its high time we review our absolute favorite I6 engines of all time.

  • Dodge Slants Six
  • Ford 300
  • Cummins Turbodiesel
  • GM’s Duramax I6

The Dodge Ram Slant-Six

Back when almost every vehicle was a front engine, RWD with plenty of room for a V8, the inline six-cylinder was the standard entry-level engine. And this made sense: An inline six-cylinder has fewer moving parts than a V6 and is easier to access. This makes it more reliable and easier to work on when something goes wrong. Finally, a piston stroke as long as the engine bay is tall means these inline six-cylinder engines make more torque.

I am not shy about my love for the Chrysler Corporation slant-six, and I’m not the only one. While every automaker had an inline six-cylinder, the slant six stood head and shoulders above the rest in its reliability and durability. It debuted in 1960 with 170 and 225-cubic-inch variations. Dodge put it in Ram trucks until 1987. It was used in industrial equipment and boats until 2000.

The final Ford F-150 straight six

1989 Ford F-150 | Ford motor company

Ford built a series of straight-six engines that were strong competitors of the Dodge Slant-Six. Then in 1965, Ford increased the stroke of its 240 cubic-inch to build a powerful 300 cubic-inch variation. This legendary engine did duty in tractors, trucks, and even a winning Baja 1000 racer.

One major strength of the Ford 300 is its long production run. The automaker fit the 4.9-liter with fuel injection in 1987. With its final compression ratio of 8.8:1, it produced 150 horsepower. It was phased out by 1997 but is still sought after to build up for race cars. The Ford 300 was easily one of the most advanced naturally-aspirated I6 engines ever mass-produced.

The Cummins turbodiesel inline six-cylinder

A red 1997 Dodge Ram 3500 truck with the Cummins I6 turbodiesel engine, parked under a bridge.
1997 Dodge Ram 3500 | Stellantis

By the time Dodge phased out its slant-six truck engine, both GM and Ford were pulling ahead with efficient and powerful diesel engines. Dodge approached Cummins about buying one of its industrial-grade 5.9-liter turbodiesel I6 for Ram trucks. The rest is history.

The Cummins I6 that debuted in the 1989 Ram 250 and 350 only made 160 horsepower. But its 400 lb-ft of torque was nearly unheard of at the time. Ram soon upgraded to an inter-cooled version, the first in pickup truck history. Every generation of Cummins I6 in the Ram truck has been more advanced, with the latest 6.7-liter version making more than 1,000 lb-ft of torque.

Chevy/GMC’s Duramax diesel I6

2020 Chevrolet Silverado 1500 Duramax | General Motors

While Dodge is the automaker that pioneered the heavy turbodiesel I6 in its heavy-duty trucks, it is General Motors who pioneered a lighter, inter-cooled turbodiesel I6 in its light-duty trucks. General Motors collaborated with Opel on a next-generation Duramax I6. The result is a 3.0-liter aluminum turbodiesel that makes up to 375 horsepower and 495 lb-ft of torque.

Though Opel helped with the engineering, the Chevrolet/GMC Duramax I6 is made in Flint, Michigan. At the time of writing, the I6 turbodiesel is available in the GMC Sierra 1500 and Chevrolet Silverado 1500. That makes them the only half-ton diesel pickups on the market.

Love I6 engines as much as I do? You’ll be happy to hear that the inline six-cylinder engine is making a comeback. At the front of the pack is Ram’s new Hurricane I6.

Next, learn how inline six-cylinder engines make more torque or watch the new Hurricane I6 in the Jeep Wagoneer put to the test in the video below:


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