The diesel that dominated Indy

The number 28 was a rarity. The 1952 Indy 500 race rules allowed cars equipped with four-stroke diesel engines twice the size of their gasoline counterparts to compete. “OK so what?” you say. Clessie Cummins was a self-taught engineer and promotional genius, just like Henry Ford (who came before him) had been. During his career, he used the Indy 500 to show how durable his diesel engines were. By 1952, Clessie had retired, but the Columbus, Indiana-based company still fostered his belief that his engines could compete in the world’s most famous race. This is the story of the famous race car that dominated the Indy 500 just to prove a point!

Cummins built a 401 cu in (6.6 L), 380 horsepower, turbocharged, inline-six, diesel racing engine that featured an aluminum block, magnesium cylinder head and crankcase. This was nothing short of revolutionary for its time! Cummins built the engine and then, to get the most out of this monster engine, turned to renowned chassis builder Frank Kurtis to build the car that surrounded it. Frank mounted the engine sideways on a radically low chassis built by his shop, Kurtis Kraft.

Kurtis recommended that Fred Agabashian be hired to pilot the beast. Come spring, the #28 was tested in a wind tunnel and then at Indianapolis Speedway. The car proved to be as powerful as expected and more of an engineering success than wildly dreamed of! The 3,100-pound car took pole position in qualifying with a speed of 138.010 mph! It also beats Ferrari’s 12-cylinder race car by nearly 4mph, no small feat! The only real problem was that the car ate its tires during qualifying. He was huge and heavy and ran like a scalded cheetah. With that modus operandi, something would become a weak link. That link appeared in tire technology, or the lack thereof.

Although qualifying broke the tires of the no. For #28, the race day strategy would take this week’s link into account and take steps to compensate for it. The car would pit once during the race for tactical tire changes. She had been built with a 50 gallon tank and could average 10 to 12 mpg; So the #28 could do 500 miles without a fuel stop if they wanted to. However, due to the tire change, Cummins made the most of the pit by planning to start the race with enough fuel for 80 laps and then tires and fuel at the same pit stop. This way they would take advantage of a lighter starting setup and not encumber the car with its design limits.

The diesel was reluctant at first and never led, but it ran strong. Once he got into his stride, he sat in fifth place for quite a few stretches. But by lap 70, it was all over for the diesel that could. At that moment the car began to vomit black smoke. The experimental car pitted at the 175-mile mark. The crew discovered that the engine was overheating. From there, it was taken to the garage and withdrawn from the race, officially due to turbo failure. It turned out that the poorly positioned design of the turbocharger allowed it to absorb rubber particles at the intake, which clogged it. Once that happened, #28 was done.

The day after the race, J. Irwin Miller (Cummins Chairman of the Board) ended the car race. “There are no plans to race the car next year,” he said. “Right now, we want to learn the value of what’s been done there and see what we’ve learned before talking about anything else.” Miller went on to say “that the experimentally equipped car has a very slim chance of winning. But we learned what we wanted whether or not the car won.”

Years later, Don Cummins summed up the #28’s contribution to Indy history by saying, “The only reason I was there was to draw attention to the fact that we were making these engines…If anyone thought that it was a Mickey Mouse engine, we wanted to be able to say, ‘Hey, your truck engine, this thing you can buy, it sat on the pole at Indianapolis.