With six weeks left before the 24 Hours of Le Mans, Audi is offering details regarding the diesel engine powering the R18 TDI.
The engine is a compact 3.7-litre V6 which uses a single turbocharger and weights around 25 percent less than the previous V10 TDI fitted on the R15 TDI. It produces around 540 horsepower (397 kW) and the exhaust manifold and VTG (variable turbine geometry) sit between the cylinder banks.
The new Audi R18 TDI engine is in accordance with the latest regulations imposed by the Automobile Club de L’Ouest (ACO), and due to its smaller size it allows a lower center of gravity and also enables the improvement of airflow through the car. The single turbocharger is also in contrast with the previous Audi Le Mans racers which all had twin turbos, but in this case Audi explains the turbocharger sits above the engine so it draws air directly through the roof mounted air scoop, converting dynamic pressure at high speeds with minimal power loss.
Audi has worked on this engine concept for the Audi R18 since 2009, testing numerous routes since then. One other interesting feature on this new engine is the unique method it uses in cooling the cylinder heads, something that Audi considers implementing on production cars.
Also instead of a ‘traditional growl’ the Audi R18 TDI makes a ‘whispering murmur’, which might sound unusual, but Dr. Wolfgang Ullrich explains it is because ‘noise is unused energy’, so this won’t be the case with ‘probably the quietest race car Audi Sport has ever built’.
