Editor’s Note: This series counts down the Top 10 engines of all time—see how the voting was done by reading our initial post.

In a hot rodding world dominated by V8s, many of you decided to think outside the V…er, box.

At #6 on your Top 10 engines list, you’ll find the first gasoline-based inline engine of the group: the Chrysler 225 Slant Six. While it doesn’t possess the cylinders or overall displacement of the other engines, the Chrysler 225 Slant Six makes up for it by delivering gobs of torque and a cockroach-like lifespan.

You just can’t kill ’em!


First produced in 1960, the Chrysler 225 Slant Six replaced Mopar’s old Flathead-style engine.

The inline engine was given the Slant Six name because of its unique, 30-degree tilt toward the passenger side of the vehicle. This design was implemented for several reasons, according to Chrysler’s original 1960 press release:

  • The center of gravity is much lower than in upright engines
  • Increased clearance for use with the Plymouth Valiant’s low-profile hood
  • Engine accessories are more accessible

The “slanted” design also allowed for the use of equal-length intake runners and header primaries. The result was improved distribution of the intake air charge and reduced airflow restriction. Combined with a unique internal cylinder design, which featured a much smaller bore than stroke, the improved airflow helped the 225 Slant Six deliver tons of torque. And when the engine’s original one-barrel carb was dumped in favor of a two-barrel carburetor (a common practice among hot rodders), the engine offered even more performance potential.

From 1960-62, Chrysler also offered a Hyper-Pak package, which included a four-barrel carburetor and numerous performance upgrades. This parts combination helped push the Chrysler 225 Slant Six’s power output to almost 200 horsepower—almost V8 range!

Still, the Chrysler 225 Slant Six became most-known for its durability during its 23-year run from 1960-83—as your fellow gearheads pointed out…

mopar 225 slant six engine on engine stand
(Image/Summit Racing – PowerNation)

Reader Quotes

“Slant Six 225! Bulletproof! –Chris L.

“Not a Mopar guy, but I have never seen anything tougher than a Slant 6 Chrysler!”–Leonard A.

“The Chrysler 225 ci Slant 6—reasonable on fuel, never stops running or wears out, and has loads of torque. My mum had one with over 300,000 miles and it never even had the tappet cover off once!” –Jeff N.

Fun Fact

The Chrysler 225 Slant Six was not only used in cars and trucks, it also provided power for farm tractors, forklifts, and boats.


The original Chrysler 225 Slant Six produced around 145 horsepower at 4,000 rpm and 215 ft.-lbs. of torque at 2,800 rpm.

Aftermarket Upgrades: Six for the Six

Because of the durability of the 225 Slant Six, aftermarket manufacturers continue to offer upgrades and replacement/maintenance parts. According to Summit Racing, six of the more popular parts include:

Editor’s Note: This series counts down the Top 10 engines of all time—see how the voting was done by reading our initial post.

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Author: David Fuller

David Fuller is OnAllCylinders' managing editor. During his 20-year career in the auto industry, he has covered a variety of races, shows, and industry events and has authored articles for multiple magazines. He has also partnered with mainstream and trade publications on a wide range of editorial projects. In 2012, he helped establish OnAllCylinders, where he enjoys covering all facets of hot rodding and racing.