If a diesel racing car sounds silly, you’l be surprised as its rivals were to learn that one claimed pole for the Indy 500. Matthew Franey reports
Pub quiz question 4,643: name the only diesel-engined car to take pole position in a Formula One World Championship event. It’s a bit of a trick question really, for the car that clinched that pole never raced on the Grand Prix tracks of Europe nor saw the hand of an Ascari or Fangio. Nevertheless, there is no denying that the Cummins Diesel Special won pole position at the 1952 Indianapolis 500, then a points scoring round of the F1 championship. And that it happened at all is testimony to one man’s vision and the efficiency of a big oil-burning motor among the methanol and gasoline-powered four-cylinder engines that had come before.
That man was Don Cummins, vice-president of engineering at the large American manufacturer and a died-in-the-wool race fan. As far back as the 1930s, company founder Clessie Cummins had been intrigued by the visits of Kaye Don and his Land Speed Record crew to Daytona Beach in Florida: Mindful of the publicity such attempts generated, Cummins issued the order to build a car that would set a series of diesel-engined speed records and also compete at the 1931 Indianapolis 500.
For this Cummins pulled strings, for while diesels now had more than mere novelty value, no thought had been given to entering one in America’s greatest race. Consequently, the Speedway’s rulebook gave no indication as to the eligibility of the car and Cummins turned to his friend Eddie Rickenbacker, owner of the circuit, for some ‘guidance’. The overcapacity car was soon entered to run and with driver Dave Evans did just that. The ’31 Cummins ran to the end of the race without one pitstop for fuel – a first in Indy history – claiming 13th place on the way.
The company returned fleetingly to Indianapolis in 1934, before the war put a halt to all racing in the States, and it wasn’t until the 1950s, and increasing demands from the public for reliable, economical engines that thoughts, Cummins’ in particular, returned once more to the 2.5-mile oval in Indiana.
Superchargers, though used for many years in the 500, were still new technology for diesel-powered vehicles, and Cummins saw Indianapolis as the ideal proving ground for their latest efforts.
At the end of ’49, Cummins summoned his chief engineer Neville Reiners to his office. The possibility of running on a par with gasoline-powered cars intrigued him, and Reiners was sent away to study the feasibility of such a project. The result was the first of the post-war Diesel Specials the Given Hornet.
The modified supercharged 6.6-litre six-cylinder engine was shoe-homed into its chassis by renowned 1 race car constructor Frank Kurtis. His Offenhauser-powered Kunis Kraft cars had dominated Indycar racing after World War II and Cummins looked to him to build a car simple enough to go the distance but still prove competitive in the tough race.
The diesel produced over 300bhp at around 4,000rpm, but it was only enough for driver Jimmy Johnson to snatch 33rd and last place on the grid at a pip over 129mph. The pole-sitter was some five miles an hour faster. Johnson never made it to the end of the 1950 race, a broken damper forcing him out at quarter distance, but he had made his way up to 16th in that Short time and for Cummins the racing bug had returned.
The Hornet was later whisked off to the Bonneville Salt Flats, where it set six diesel world speed records, while Cummins and Reiners turned their attention to a car that would not just make the grid of the Indy 500, but win it. Accomplished Speedway racer ‘Flying’ Freddy Agabashian was approached to drive for Cummins in the 1952 race. The concept for the new car was revolutionary and they wasted no time in demonstrating to Agabashian just how futuristic the Diesel Special would be.
“I remember we went out onto the backstretch of the track,” he recalled some years later. “They laid out the plans of the car on the ground and put a four-inch Coke can on top. That was how far I would be sitting off track.”
The secret to the exceptionally low centre of gravity of the new car came after Cummins and Kurds realised the latest six-cylinder diesel could be laid on its side in front of the driver. Kurtis then ran the driveshaft back past Agabashian’s Hi hip rather than under the seat, allowing the designer to drop the entire body of the car below wheel level. The sleek ‘roadster’ was nearly live feet wide, but its 18 inch wire wheels came level with the driver’s head.
For the first time in an Indy racer, aerodynamics had played a major part in design and packaging. Use of a wind tunnel meant that the windshield and body panels were constantly tweaked and vital power was gained when Reiners discovered that by manually closing radiator shutters on the straights, the diesel would produce 18 extra horsepower. Cockpit adjustable shock absorbers also maintained the car’s ride height as fuel loads decreased.
Development had also seen its way into the new engine, which produced 430bhp at 4,500rprn thanks in part to the first use of a turbocharger in the race. The stock Cummins truck engine weighed in at 1600lbs – three times that of an Offenhauser – but extensive use of magnesium and aluminium allowed the engineers to pare off nearly a thousand of these, making the Diesel Special merely heavy rather than obese.
The stunning red and yellow machine made its debut at Indianapolis in March 1952, completing countless laps in testing under the watchful eye of Cummins and Reiners, Agahashian sought to perfect the balance and rid t lie car of crippling tyre wear. ‘Flying’ Freddy pounded the oval throughout the Spring, studied intently by Cummins’ rivals. But the team was intent on not giving them a clue as to the potential speed of the mysterious car.
Not once did he complete a flying lap, choosing to charge round one half of the track, before backing off fin the second portion, giving the impression that the car was not yet on the pace. Then he would reverse the procedure, building up speed gently, before roaring through the last mile flat out. It was classic sandbagging. Only Agabashian and his team knew the Cummins Diesel Special’s potential. The others would have to wait for the first day of qualifying to find out.
Conditions on that opening day were perfect, with rival Andy Linden one of several drivers to break the lap record raising the mark to an average of I37002mph over four laps. The Cummins was next, Agabashian at last able to run his car wide open for the 10-mile measured run. After a couple of laps, he took the green flag. His very first lap was a new record 139.104mph. Over the next three, despite rubber being tipped from the right rear tyre he held his nerve to post an average of 138.010mph. The Cummins Diesel special was on pole.
After qualifying the Spedway’s president Wilbur Shaw, himself a three-time winner and not a man to miss a soundbite, declared the accomplishment “a feat in the automotive experimental field before equalled in the history of the Indianapolis 500.”
Sadly for Cummins and his crew, the race did not match the expectations set in practice. Agabashian was unable to make pole position count, suffering chronic turbo lag as they took the start. After dropping to 12th place, he worked his way steadily up to fourth before a preventable failure ended his race.
“The turbo intake was underneath the radiator grill,” recalled Agabashian, “and rubber dust from the tyres ofthe cars ahead entered the inlet like sawdust, packed in the turbo and cut off the air. We pitted on lap 72 and pulled the car from the race.”
That the car had literally vacuumed up the rubber marbles was unfortunate, but it was avoidable. Frank Kurtis maintained that Cummins failed to heed his warning about the intake and relocate the turbo, while Reiners retorted that a turbocharger that would have allowed the rubber to pass through had been ordered but never delivered.
Regardless of the final outcome, Cummins had proved the worth of its engine and, unwittingly, changed the future of Indycar racing forever. For while the diesel engine was not to make a lasting impact on the series, the low-slung roadster Frank Kurtis had created for it did.
The superb aerodynamics and uneven weight distribution (the car was balanced mid-comer) of the Cummins was replicated by Kurtis in his next creation: the Offenhauser-powered KK500A. That wasn’t a bad car either… It won the next three Indy 500s. But that’s pub quiz question 4,643.
Additional research by David Moore