Truckers vs Turbines: The 1960s Diesel Challenge

In the 1960s, diesel engines were the backbone of American transport. They moved heavy goods across long distances, but some engineers thought they were too bulky and complex for future needs. They imagined a lighter, cleaner power source that could replace diesel. The gas turbine seemed like the answer. It had proven itself in World War II aircraft, and military planners believed it could power trucks and tanks. The idea spread quickly among truck makers: Ford, GM, Mack, Kenworth, Freightliner, and Chrysler all invested in turbine research. International Harvester (IH), a major truck and farm equipment brand, joined the movement but chose a different path. Instead of building turbines from scratch, IH bought Solar Aircraft Co. , a San Diego company that had built gas turbines for ships and stationary use. By 1963, Solar became an IH subsidiary. The first test was fitting a Solar turbine on a farm tractor called the HT‑341. It made headlines but turned out to be noisy, complex, and fuel hungry. IH abandoned the tractor project in 1967 but kept looking for turbine solutions.

That same year, IH started developing a semi‑truck powered by a turbine. The result was the Turbostar, unveiled on January 11, 1968. It used a CO‑4000 cabover base and included minor styling changes like a smaller grille, higher ride height, and four headlights. Inside the cab was Solar’s B‑series turbine: about 1, 585 pounds—half the weight of a diesel engine of similar power—and delivering 300 horsepower. The turbine spun at 34, 000 RPM and was down‑rated to 4, 000 RPM at the output shaft. A custom recuperator recycled exhaust heat to improve fuel efficiency, and IH removed the traditional radiator because the turbine ran cool enough. The truck also switched from a 10‑speed to a 5‑speed transmission. IH marketed the Turbostar as the “Truck of the Future, ” claiming turbines would be ready for commercial use by the early 1970s. However, diesel engines continued to improve: they became lighter, cheaper, and more powerful. Truck drivers preferred the reliability of diesel over an untested turbine system. As a result, the Turbostar never gained traction, and IH eventually stopped production. Solar Aircraft Co. survived beyond IH’s turbine experiments. The company found a niche in oil‑field equipment, where turbines proved useful and profitable.

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