In fact, that history goes back to the very first Indy race, in 1911. As a young man in central Indiana, Clessie Cummins, who later would found Cummins Engine, was well-known for his mechanical abilities. He worked for a short time in four early automotive-related industries before settling at Nordyke and Marmon, which produced the Marmon car. On May 30, 1911, Clessie served as a member of the pit crew for the Marmon Wasp. Driver Ray Harroun was the first winner of the Indianapolis 500 mile race.
Cummins engines appeared at the race in 1931, 1934 and 1950.
In 1952, with diesels now a mainstay of the trucking industry, Cummins returned to the Indy 500 with another innovation new to the speedway: turbocharging. The car had a unique side-lying engine design, which enabled an offset drivetrain and lower center of gravity for better handling on the banked turns. The #28 Cummins Diesel Special was also the first Indy car ever tested in a wind tunnel for aerodynamics.
Freddie Agabashian took #28 out on the brickyard and tore the tread off of his front right tire while capturing the pole with the fastest one-lap time (139.104 mph) and four-lap time (138.010 mph) in Indianapolis Motor Speedway history. The Cummins Diesel Special was retired midway through the race as the turbocharger inlet became clogged with rubber debris from the track - but it had established turbocharging as a viable technology on the track, as well as helped engineers refine improvements to the breakthrough Cummins PT fuel system.
Cummins has put together a video with historical footage of those time trials:
You can read more on the Cummins website, as well as in an extensive 2008 article in Diesel Power