Cummins rolls out historic diesel racer for Goodwood
No.28 Cummins Diesel Special to run with motorsport’s game-changers at the Festival of Speed
One of the most famous diesel-powered race cars of all time, the No.28 Cummins Diesel Special, will bring its distinctive diesel growl to the Goodwood Festival of Speed taking place June 29 to July 2 as it runs up the iconic hill climb track in a rare public appearance following restoration of the original JT-600 engine.
In 1952 the car created a diesel sensation with a record-breaking qualifying speed of 138mph (222km/h) to take pole position at the Indianapolis Motor Speedway 500 race, then a points scoring round of the F1 championship.
To the astonishment of the industry, the experimental Diesel Special with the 430hp (321kW) Cummins engine had outperformed some of the fastest petrol-powered race cars in the world to become the first – and only – diesel to take pole position.
The Diesel Special was invited to run at Goodwood by the Earl of March as part of a fabulous line-up of historic race cars to reflect the ‘Peaks of Performance – Motorsport’s Game Changer’ theme for the 2017 Festival. In today’s language, No.28 would be described as a ‘technology disruptor’, as not only did it unleash the potential of the diesel engine, but also introduced some remarkable innovations to Indy race-car design.
Not only was No.28 the first Indy 500 race car to be turbocharged, it was the first to be fully aerodynamically designed and wind tunnel tested. With a radiant red-and yellow colour scheme, the Diesel Special handled superbly on the track due to a radically different Kurtis-Kraft roadster chassis, designed lower and longer to accommodate the diesel engine.
“Everywhere you look on No.28 you find technology innovations and that’s why back in 1952 it became known as the Cummins laboratory-on-wheels,” said Bruce Watson, retired Cummins engineer and hands-on restorer who brought the race car and its diesel engine back to original racing condition and will pilot the car on the Goodwood track.
“Today the car remains a uniquely mechanical experience to drive, it feels pure and solid without an electron flowing anywhere. After years of restoration work, we finally got the engine to growl back into life a year ago. Although very few of the components have changed since it first raced at Indy, modern technology did come to the rescue with 3D printing to replace a corroded magnesium water pump just before heading to Goodwood,” added Watson.
The race engineered JT-600 diesel engine was uprated by more than twice the standard horsepower to 430hp (321kW). Although the engine made extensive use of lightweight aluminum, it remained essentially the same as the in-line six-cylinder engine that had recently entered service with trucks in North America.
The 6.6-litre, 24-valve engine featured Cummins revolutionary Pressure-Time (PT) fuel system, with the pump suppling the fuel at low pressure to a common rail and then injected at high pressure by unit injectors to each cylinder. The PT system, combined with the first use of a turbocharger at Indy, enabled a faster engine speed of up to 4,500 rpm.
The PT system was newly developed by Clessie Cummins and the engineering team at the Company headquarters in Columbus, Indiana, where the Diesel Special proudly resides today, located just 50 miles from the Indianapolis Motor Speedway.
To accommodate the heavier weight of the diesel engine, the 1088kg race car featured dual-calliper disc brakes and two shock absorbers on each wheel. The use of independent front suspension was unusual for Indy race cars at that time, replacing the more typical rigid front axle. The result was a highly aerodynamic car powered by a very strong, turbocharged diesel engine.
Pole Position At Indy 500
With fearless driver Freddie Agabashian at the wheel, the No.28 Cummins Diesel Special attracted national attention positioned at the front of the start line. With the race underway, the heavier diesel car fell back from pole position as the turbocharger took its time to get the engine up to full power. Steadily, No.28 climbed back up the field to be in fourth position as the diesel engine strength and aerodynamic design took effect.
Then, at the 175-mile mark, with an average speed of 131.5mph (212km/h) the Diesel Special was forced to retire from the race due to a clogged turbocharger resulting from the intake of debris from the track – ending hopes of victory for the many thousands of Columbus residents who attended to cheer on No.28.
After the race ended, the entry rules were changed, effectively making No.28 the last diesel powered race car able to compete in the Indianapolis 500. However, the car had by then achieved its purpose of showcasing the diesel engine and highlighting the ability of the new PT fuel system and turbocharging to transform performance.
The huge publicity achieved by No.28 immediately boosted sales of Cummins truck diesels in North America, with the recognition that it was the engine that had sat on pole position at the Indy 500 race.
Visitors to the Goodwood Festival of Speed will be able to see the legendary diesel racer up close in the paddock area and when it takes to the track as part of the ‘Americana’ car batch on the hill climb. The Cummins pit crew will be on hand to provide an insight into the technology that made the No.28 Cummins Diesel Special so famous.
June 30, 2017
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