The best-known U.S. aircraft engine of World War II had its roots in auto racing and the Indianapolis 500.    -Photo courtesy National Air and Space Museum.

It’s a little ironic that in the USA, the Allison V-1710 is the best-known American aircraft engine of World War II. In its time, the Allison was a bit of an oddball. The U.S. military establishment, the Navy in particular, had a clear preference for air-cooled radial engines for combat aircraft, based in part on the theory that without a liquid cooling system, the radial was less vulnerable to enemy fire. As a result, the Allison V12 was an outlier in the USA’s military arsenal—the only native-born liquid-cooled engine to see regular combat duty in WWII.

The Indianapolis company that built the V-1710, car buffs will be pleased to know, was founded by James A. Allison as the Indianapolis Speedway Team Co. in 1915 to build and maintain race cars for the Indianapolis 500. (Among his many business interests, Allison was a co-founder of the Speedway.) Following a big victory in the 1919 500-Mile Sweepstakes, the shop’s focus shifted to general engineering work, and the firm next made its name producing refined versions of the Liberty V12 aircraft engine. After the death of James Allison, the company went through several name changes and a succession of owners, including Eddie Rickenbacker, the Fisher brothers, and ultimately General Motors in 1929. The first major product of the Allison Engine Co. under GM management was a large V-12 aviation powerplant called the V-1710.

The name V-1710 came from its military designation, where V indicates a V-type layout and 1710 is the displacement in cubic inches—achieved here via a 5.5-in bore and a 6.0-in stroke. With a 60-degree vee angle, four valves per cylinder, and a single camshaft for each bank, the engine was reasonably light and compact: 1400 lbs and 86 inches long. And it employed automotive-style construction and a remarkably modular and symmetrical layout, which made it adaptable to an astonishing variety of applications.

First intended for airships, the V-1710 saw use in a broad range of winged aircraft, from the midships-engine P-39 and P-63 fighters to the twin-engine P-38 Lightning, which used turbocharging to boost its high-altitude performance. With more than a decade of development, output rose from 1,000 hp to 1,500 hp, and up to 1,875 hp in experimental form. There was even a V-3420 variant, which was essentially two V-1710s in tandem driving a single shaft.

The Allison often suffers in the inevitable comparisons to the other famous liquid-cooled V12 of WWII, the Rolls-Royce Merlin. But in truth, the American-designed engine offered some advantages of its own. With its relatively simple, automotive-style construction and low component count, the V-1710 was tremendously rugged and reliable. And better yet, it could be turned out in great numbers in a short time at very low cost. By the end of the war more than 69,000 engines were produced, and they were an indispensable part of the Allied victory.

Naturally, with such vast numbers produced, when the war ended the V-1710 soon arrived in volume on the military surplus market, selling at a fraction of the original cost. Complete engines could be obtained for as little as $350, down to $200 at one point. On a horsepower-per-dollar basis, it was an unbeatable deal. Surplus Allisons found a home with air racers, the unlimited hydroplane crowd, and even with drag racers, and they were a familiar sight in the motorsports world for decades.

In the ’50s, the Arfons brothers from Akron, Ohio powered a whole series of Green Monster race cars with Allison powerplants. But arguably the most far-out of the Allison drag racers was Jim Lytle of Southern California, who constructed a succession of V-1710 machines, each one wilder than the previous one. The ultimate Lytle creation, Quad Al, used four of the big aircraft engines on a 4WD chassis (below). In truth, Quad Al was a mock-up without a working drivetrain, incapable of moving under its own power. But it certainly made a lasting impression.