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Audi diesel marks 'biggest ever challenge' |
The V12 TDI diesel engine, which will propel the Audi R10 in the 2006 Le Mans 24 Hours, marks many motor racing 'firsts' - and breaks new engineering ground.
The totally new powerplant has a cubic capacity of 5.5 litres - the maximum permitted at Le Mans - sending Audi into previously unexplored diesel-engine terrain with power exceeding 650 hp and a massive torque of more than 1100 Newton metres.
"This engine is the specifically (for its size) most powerful diesel there is in the world and, up until now, the biggest challenge that Audi Sport has ever faced in its long history," explained Ulrich Baretzky, head of engine technology at Audi Sport. "There has never been anything remotely comparable. We started development with a clean sheet of paper."
The V12 TDI used in the R10 is the first Audi diesel engine with an aluminium crank case. The cylinder-bank angle is 90 degrees, while the engine has four valves per cylinder and twin overhead camshafts.
The fuel induction is made by a modern "Common Rail System". The injection pressure easily exceeds the 1600 bar achieved in production cars, while the ignition pressures also reach values never previously seen in any Audi engine.
The turbo pressure produced by the two Garrett turbochargers is limited by the regulations to 2.94 bars (absolute), while the diameter of both engine air intake restrictors is also restricted, to 2 x 39.9 millimetres.
The engine's power and the high torque are available to the driver practically from idling speed - a characteristic of diesel technology - with the usable power band between 3000 and 5000 revs per minute, much lower than racing petrol engines.
Something else unfamiliar to the drivers will be the low noise level and, unique for a racing engine, the smooth running of the engine. At high speeds the 650 hp engine can not be heard from the Audi R10 prototype's "open" cockpit while there is hardly any vibration.
On the outside, the twelve-cylinder produces a faint, but deep sound that some would struggle to identify as a diesel. Indeed, the new R10 can only be recognised acoustically as a diesel-powered sportscar during the warming-up process or in the pit lane.
