Ford X-8: The Strange 14-Inch, 30-HP Engine That Almost Changed History

14 inches long, 17 inches wide and tall, and just 30 horsepower. This isn't a motorcycle engine but Ford's X-8 eight-cylinder powerplant developed in the 1920s as part of a secret project to underpin a new car replacing the Model T. The engine with its unique X-shaped design never reached production, yet it remains one of the strangest engineering experiments in Ford history.

X-8 Design: Four Cylinders Per Arm

The core difference between the X-8 and conventional V8 engines lies in cylinder arrangement. Instead of two opposing banks in a V shape, the eight cylinders were placed around a central crankshaft in an X configuration. The engine had two groups of four cylinders, but describing it as two connected V4s isn't entirely accurate. Each group was arranged in an X, making it closer to two X-4 engines joined to a single crankshaft. This layout explains its extremely compact size: roughly 17 inches in height and width, with a length of just 14 inches. A displacement of 108 cubic inches—about 1.77 liters.

Air Cooling and Eight Spark Plugs

The original design relied on air cooling. That explains the large fans on both sides of the engine. Cylinders were finned to increase surface area and dissipate heat. The engine used eight spark plugs with a relatively complex intake and exhaust system. Each side had a manifold serving four cylinders with both intake and exhaust passages. Ford's patent revealed that one version of the design could produce up to 30 horsepower, though The Henry Ford museum doesn't specify an official power figure for the engine currently on display.

Why Ford Abandoned the Project

Despite years of development, engineering problems prevented production. Oil leaking into the cylinders was a major flaw. The low-mounted spark plugs were exposed to dirt and mud from the road. Engineers tried converting the design from air cooling to water cooling, but the project continued to suffer from multiple issues. As development stretched to 1926, Ford began searching for a more practical solution.

The Road to the Flathead V8

Before Ford introduced its famous Flathead V8, Henry Ford embarked on an unconventional engineering experiment with the X-8. Developed in the 1920s, it was meant to power a new car replacing the Model T. But the engineering failure did not stop Ford. That later shifted efforts to developing a conventional V8 that became one of the company's most iconic engines. The secret project ended, but left behind a unique engineering tale of a 14-inch, 30-horsepower engine.