Come on, admit it. There wasn’t a diesel car owner in the country who didn’t have a tear in his eye when Audi won the 2006 24 Hours of Le Mans in their diesel R10 sports car. After years of being condemned to use the leaky old diesel pump around the back of the service station, drivers of oil burners have finally earned the right to be accepted at all levels!
Of course, acceptance might have taken even longer to come by if Rudolf Diesel had succeeded in his first attempts at building a compression-ignition engine that ran on something other than petrol. After meddling with ammonia for a while, he attracted backers to fund an engine that would run on the mountains of coal dust piled up in the Ruhr valley. In 1893, his first prototype, using highly pressurised air to blast the sooty fuel into the combustion chamber, blew its silly head off, but he managed to produce a working version before shifting focus to his successful oil-burning design.
In 1900, at the World Exhibition in Paris, he demonstrated his new engine that ran on peanut oil. Commercial diesel fuel as used today is extracted from petroleum crude oil, but biodiesel, based on animal or vegetable fats and oils, gets the job done just as well.
Cars with diesel engines have been successfully raced before Le Mans this year. In the 1930s, Clessie Cummins ran a diesel car at 162kph at Daytona, and in 1952 a Cummins diesel racer took pole at the Indianapolis 500 race. It led for most of the way, but broke down after the engine ingested debris from the track through its air intake. In 1998, BMW won the Nurburgring 24 Hour race with a 320d sedan, beating a couple of hundred petrol-engined cars on the way, and Audi’s R10 preceded its Le Mans victory with a win at the Sebring 12 Hour earlier this year.
Diesel engines have been successfully used in ships, cars, motorcycles, aircraft and farming and earthmoving equipment. The most impressive oil burner of all time, though, is the Wartsila-Sulzer RTA96-C turbocharged two-stroke diesel engine, the largest reciprocating engine in the world, and one of the most efficient.
The bores of this monster’s 14 cylinders each measure almost a metre across, and the piston stroke is a whopping 2,5m, giving a capacity of 820 litres per cylinder, or 25Â 480 litres in total. The engine, also available with fewer cylinders, was designed for container ships, and maximum power is about 80Â 000kW, or 106Â 000 horsepower. At 23m long, and weighing more than 2Â 000 tons, the Wartsila-Sulzer is the size of a four-storey house. The 300-ton crankshaft spins at just 102rpm, and the engine devours about 7Â 500 litres of fuel per hour in its most economical mode.