Diesel Engines

Although diesel engines debuted in commercial trucks as early as the 1930s, widespread adoption waited on postwar advances:

• Kenworth’s Standardization (1933): Kenworth became the first U.S. truck maker to make diesel engines standard and even offered sleeper cabs as an option, signaling the dawn of diesel in heavy-duty service.

• GM’s Detroit Diesel Research (1938–1950s): After acquiring Winton Engine Co. in 1930, GM’s Research Division developed the Series 71 two-cycle engine—lightweight, powerful, and modular—initially for marine and military use. By the mid-1950s, these engines had proven themselves in tanks, landing craft, and generators, paving the way for their acceptance in commercial trucks seeking both reliability and fuel savings.

Government-driven wartime research into fuels and materials further refined diesel combustion and engine metallurgy, reducing maintenance intervals and lowering operating costs compared to gasoline counterparts. By 1958, over 70% of Class 8 trucks rolling off assembly lines were diesel-powered, cementing diesel’s status as the king of heavy-haul propulsion.