The Mopar stories site

Kaiser-Jeep Tornado Six inline engines


Military and civilian Jeeps were exclusively four-cylinders for quite a while; indeed, Willys’ main contribution to the engineering of the military Jeep had been its sturdy, reliable “Go-Devil” four-cylinder engines. Those engines were clearly not enough for the new Wagoneer wagon or Gladiator pickup.

Engine designer A.C. Sampietro, who had developed the Nash-Healey’s engine using inclined valves, pushed through a rather unconventional engine, as befitted an unconventional wagon (the first to have 4x4 with an automatic, not to mention 4x4 with an independent front suspension—which was an option; buyers could also get a conventional front suspension).

Kaiser-Jeep Tornado Six (OHC) engine

The Tornado Six was the first mass-produced overhead cam engine in America (though not the first overhead cam engine); it had six lobes driving its 12 valves via rocker arms, a design to come back in the Ferrari V12; redline came at 5,200 rpm. The rocker arms cleverly used steel stampings on ball pivots, presumably a cost saving measure (like the six-lobe cam). The chain drive had wide links for noise reduction, and spring-loaded pads to reduce movement and wear. Intake valves were 1.895 inches, while exhaust valves were 1.618 inches; lift was 0.375 inches. The carburetor was a Holley single-barrel.

The block was a cast iron design, based on Continental’s work for Kaiser-Frazer, Graham, and Checker; it differed partly in having a larger bore (3.344 vs 3.3125 inches), but kept the old 4.375-inch stroke. The crankshaft was redesigned for the Tornado.

The heavy cast iron head had an integrated intake manifold, saving some weight; the cast iron exhaust manifold was bolted on. Aluminum saved weight in the camshaft, rocker cover, and other parts, so that the engine weighed 575 pounds, including the flywheel, making it heavier than many competitors. Domed pistons and hemispherical heads provided a great deal of efficiency, as they did in contemporary Chrysler “double rocker”  V8s—later to be called Hemis. The Kaiser design, though, avoided some of the heavy weight and massive size of the Chrysler valvegear through the overhead cam setup; while moving the valves a little off-center made spark plug replacement, then an annual-or-more affair, easier. The advantages of the clever setup was higher torque and greater efficiency.

The 3.8 liter engine (230.5 cubic inches) was “the biggest six of ’62,”  according to the marketing, and produced 140 horsepower (gross) at 4,000 rpm; more to the point, it provided 210 pound-feet of torque at 1,750 rpm. These figures were similar to the 225 cubic inch Chrysler slant six, but some believe that engine was optimistically rated, while Road & Track measured the Kaiser six at 144 horsepower—more than advertised.

Closed crankcase ventilation, still a new technology, let Jeep set oil changes at a generous 6,000 miles, a major maintenance improvement over just about all competitors, while major lubes were set at 30,000 miles. Oil ranged from SAE 5 to SAE 30 depending on temperature, with an oil pump rated at 50 psi.

Chrysler had made the alternator standard on its 1960 Valiants, a major move forward; the 1962 Wagoneer had a 35-amp alternator and electronic voltage regulator, too, just like the Valiants.

On paper, this was a phenomenal engine. In reality, the valvegear was, like that on the Hemis, far too large; cam issues appeared due to poor lubrication; and the engine tended to leak oil. The military Gladiators kept using the Tornado engine, whose production shifted to Argentina after a while in the United States, but civilian Wagoneers and Gladiators moved on to much newer engines made by, ironically, American Motors—the company which eventually purchased Jeep. The AMC engines had about the same output, from about the same displacement, but the engine was tougher, more reliable, and quite possibly cheaper, even when purchased rather than made in-house. There was a reason Chrysler had abandoned, at least for mass production, hemispherical heads. But these engines are another story.

Current and future

Support us with Patreon

Books by MoTales writer David Zatz

Copyright © 2021-2024 Zatz LLC • Chrysler / Mopar car stories and history.

See our YouTube channel!About Motales/Editorial Guidelines

See the modern Tornado Six — officially, the GME T6.