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The No. 28 Cummins Diesel Special was the technology wonder of its day. More than six decades later, high technology is helping get the record-setting race car back on the track that made it famous.

Cummins engineers, using 3D printing and computerized tomography scanning, created a new water pump for the car, which will return to the Indianapolis Motor Speedway later this month after setting a one-lap track record of 139 miles per hour in qualifying for the pole position in the 1952 race.

“Without 3D printing, we would not have gotten this project done in the time frame that we had to do it,” said John Rupp, Advanced Manufacturing Technical Advisor at the Cummins Technical Center in Columbus, Indiana (U.S.).


To commemorate Cummins’ 100th anniversary, the 2019 Indianapolis 500 will include a parade lap featuring the five company-engineered cars that participated in previous races, the first in 1931 and the last, the No. 28 car, in 1952.

Cummins’ founder Clessie Cummins occasionally used the 500 to demonstrate and promote the virtues of his company’s engines. By 1952, he had left the company, but the goal was essentially the same.

Taking advantage of rules allowing for larger diesel engines, a crew of Cummins’ engineers and technicians used a modified truck engine in the No. 28 car, with the first turbocharger ever used at the track. Some parts were milled from aluminum or magnesium to reduce weight. The team used a wind-tunnel to design a more aerodynamic car body.

An air of secrecy surrounded the effort in the days before the 1952 race and many interpreted that silence to mean the car was a flop. Imagine the surprise when the Cummins Diesel Special captured the pole with a four-lap average of 138 miles per hour, and set the single lap record. It would complete 70 laps (175 miles) in the race that year before retiring with a clogged turbocharger caused by rubber debris on the track.


Over the years, some parts on the No. 28 car didn’t age particularly well, according to Greg Haines, an Off-Highway Design & Development Leader at the company and a member of the Cummins History & Restoration Team. The team worked to get the Cummins cars running again for the anniversary.

The water pump, one of the custom parts made of magnesium to reduce weight, was especially concerning. Haines said it was pitted all the way through in one place and very thin in others. To make matters more challenging, no plans for the pump could be found to make a replacement.

It was around this time that the Cummins Diesel Special was invited to participate in the 2017 Goodwood Festival of Speed, which describes itself as “motorsport's ultimate summer garden party.” The hill-climb in West Sussex, England, features modern and historic racing vehicles, and draws big crowds of devoted fans. The Cummins Diesel Special participated in the event in the late 1990s but sat for many years after. It would never make it without a new pump. Suddenly the clock was ticking again for No. 28.

There wasn’t time to make a new part using traditional sand casting methods, so the Cummins team turned to 3D printing. The company had been studying the technology for use in manufacturing for several years, Rupp said, but it had not yet purchased any printers capable of creating metal objects one ultra-thin layer at a time.

Building a new pump was a great chance to tackle a problem facing the company when it comes to aftermarket parts for older engine models.

“A real problem we face in the aftermarket space is finding a supplier willing to manufacture a 40-year-old design that was once a high-volume part to fill an order for two or three parts economically,” said Brett Boas, Director of Advanced Manufacturing at the Cummins Technical Center in Columbus. “The tooling to make the casting just no longer exists. Additive technology solves this problem.”

Cummins worked with 3rd Dimension Industrial 3D, an additive manufacturing company in Indianapolis. The old pump was scanned to “reverse engineer” its unique features and create a digital file for the 3D printer to use.

In less than a week, the new part was printed and ready to go and No. 28 was off to Goodwood.


The History & Restoration Team is using the same techniques to restore a rare Model F diesel engine found in the basement of the Cummins’ Corporate Office Building, partially disassembled and missing parts. Considerably older than the Cummins Diesel Special, the Model F engine was produced from 1924 to 1931 to power lighthouses, industrial shovels and other uses.

Cummins engineers are reverse engineering any missing parts and using 3D printing. They hope to have the engine running by the company’s anniversary celebration in June.

“The 3D scanning, reverse engineering, and advanced manufacturing technology that are available today are helping to make these projects possible,” Haines said. “This is an excellent example of using modern technology to restore our historic artifacts.”

Watch: The No. 28 Cummins Diesel Special run a test lap at the Indianapolis Motor Speedway (April 2019).