1952 Cummins diesel racer. Click image to enlarge
Article and photo by Bill Vance
Diesel engines were not traditionally known for high performance, although Audi recently shattered that idea with its R10 diesel powered racer. Their forte was long life and superior fuel economy. That’s changing with the application of turbocharging and very high pressure common rail fuel injection. Dome diesel-engined cars are as fast as gas-powered cars of just a few years ago.
But in the era when diesels were still known as smelly, smoky, noisy and slow, it may come as a surprise that diesel powered cars competed in the famous Indianapolis 500 mile race, not once, but four times, and did quite well.
The Indy diesel effort was mounted by Clessie L. Cummins, who in 1919 had decided to add diesel engines to his Columbus, Indiana machine shop business. He launched the Cummins Engine Company which began building single-cylinder engines and enjoyed enough early success to soon move into bigger industrial and marine power.
In 1935 Cummins convinced Auburn to offer a diesel-powered model. Unfortunately, Auburn went broke before this came to fruition, and it would be Mercedes-Benz that introduced the world’s first diesel-powered production car, the 1936 260D.
The entrepreneurial Cummins was also a racing enthusiast (he had crewed for Ray Harroun in 1911 when he won the first Indy 500). Thus, when Cummins wanted to publicize the durability of his Model U diesel engine he turned to Indy. He knew the diesel had speed potential because he had installed one in a Duesenberg chassis which exceeded 100 mph on Daytona Beach in February, 1931.
Indy officials agreed to allow a diesel-powered racer into the 1931 race as an experiment, provided the car could average at least 113 km/h (70 mph). The Cummins easily surpassed that, qualifying at more than 156 km/h (96.9 mph), albeit the slowest qualifying speed.
The diesel racer’s mission was to demonstrate the diesel’s durability and economy and it fulfilled the role admirably. It ran the entire 500 miles (805 km) non-stop, averaged 139 km/h (86.2 mph), finished 13th, and got 16 miles per (U.S.) gallon of diesel oil.
Cummins came back to Indy in 1934 with two cars. Because some of his engineers favoured two-stroke engines while others preferred four-strokes, Cummins decided to enter supercharged four-cylinder versions of each.