The Willys engine praised for helping win the Army jeep contract was the Go Devil. Officially designated the L-134, it was a four-cylinder, flathead engine developed under Willys chief engineer Delmar “Barney” Roos.
Willys entered the 1940 Army trials with its Quad prototype. Although the vehicle was heavier than the Army’s target, the Go Devil produced more power than the competing engines and was paired with a robust transmission. That combination gave Willys strong cross-country performance and helped make its design attractive for military production.
The L-134 displaced about 134.2 cubic inches and used an L-head layout, with its valves positioned beside the cylinders. It powered the Willys MB and, under license, the Ford GPW during World War II. The engine also continued into early civilian Jeep models, including the CJ-2A.
A common mix-up is confusing the Go Devil with the Hurricane, its later F-head successor. The Tornado and Dauntless were also later Jeep engines, but neither was the engine associated with winning the original wartime contract.