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Mystery Machine - Pilot Injection

The Legend Of Clessie’s Two-Stroke

Jan 7, 2014
Photographers: Sean P. Holman
In 1934, Cummins campaigned two identical Duesenberg race cars at the Indianapolis 500, each fitted with a version of the company’s legendary H-4 four-cylinder engine. For the Cummins Engine Company, the Indianapolis 500 was an important testbed for proving the durability of the company’s diesel engines. As the story goes, Cummins founder Clessie Cummins wanted to resolve a debate within the diesel engine industry of which design was better: the two-stroke, or the four-stroke. Car Number 5 was fitted with a two-stroke version of the H-4 and shared 95 percent of its parts with the four-stroke H-4 fitted to Car Number 6.
Stubby Stubblefield piloted the Number 5 two-stroke car to an average qualifying speed of 105.92 mph, nearly 4 mph faster than the four-stroke Number 6 car, driven by Dave Evans. During the race, the Number 6 car suffered a transmission failure, which took it out of the race, while the Number 5 car and Stubblefield fought through various issues to finish in 12th Place, which to this day remains the highest finish for a diesel-powered vehicle in the Indianapolis 500 race.
Despite Stubblefield’s efforts to prove the viability of the two-stroke design, Car Number 5’s engine ended the race in such poor condition that it was subsequently removed by Cummins and riding mechanic Thane Houser. For years, rumors persisted about the whereabouts of Car Number 5’s engine, with stories saying it never made it back to the Cummins Columbus, Indiana, headquarters, instead ending up in the East Fork of the White River.
In the October 2003 issue of Car and Driver magazine, legendary automotive scribe Brock Yates perpetuated the rumor by writing the following paragraph in his “When Cummins Diesels Assaulted Indy” article:
“When the Stubblefield engine was finally shut down in the garage area following the race, it contracted as it cooled and seized into a solid hunk of fried aluminum. Clessie Cummins angrily closed the doors, and he and Houser set to yanking the wrecked engine out of the car. They loaded it into a truck and drove to a bridge over the White River. In the dark of night they pitched the broken engine over the side, thus ending Cummins’ brief flirtation with two-cycle engines, a policy that continues to this day.”
Various accounts of this story have been retold by diesel fans over the years and continue to be a topic of conversation amongst Cummins faithful and enthusiasts alike. Wanting to know if the story had legs, I spoke with Bruce Watson, Cummins historical curator, who was able to put the legend to rest once and for all, allowing us to help set the record straight on this popular myth.
Watson explained to us that due to the sheer size and weight of the engine, the general consensus of those in the know was that the story was more folklore than reality, but without knowing the location of the fabled engine, it was a difficult rumor to disprove. In fact, the tale was so convincing that a professional research diver approached Cummins in 2012, offering to assemble a team to locate the engine in the waters of the White River.
While the gesture was appreciated, it came a little too late, as a dusty, covered engine was discovered in the back of a storage area at the Indianapolis Motor Speedway earlier that year. While it was suspected to be the missing engine, the pedigree wasn’t confirmed until some extremely high-quality photos in the IMS archives showed the serial number on the engine to be a match for the engine photographed in Car Number 5—finally solving the mysterious whereabouts of Cummins’ two-stroke H-4.
Today, the reconditioned two-stroke H-4 engine sits proudly in the lobby of Cummins headquarters, on display next to the Number 6 car, which still has the original four-stroke H-4 under the hood. Car Number 5’s chassis, which was later stretched and fitted with a six-cylinder engine for a subsequent race at Daytona, is currently in the proper hands and awaiting restoration.



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