Audi drives diesel onto the race track

Audi

is aiming to take diesel out of the bus lane and into the fast lane by attempting to win the Le Mans 24 hour race on Saturday with its R10 diesel sports car.

Showcased at the Michelin 2006 Challenge Bibendum sustainable mobility event in Paris, the Audi R10 is powered by a 5.5 litre, 12-cylinder, bi-turbo TDI (direct-injection diesel) engine. An engine size of 5.5 litre is the maximum permitted in Le Mans.

The V12 power plant is manufactured entirely from aluminium and generates a torque of over 1100 Newton metres, which Audi says makes it the most powerful diesel car in the world. Special gearboxes had to be fitted to withstand the unusual forces.

The usable power band lies between 3000 and 5000 revs per minute, which is an unusually low range for a racing engine. This means the driver will need to change gears less due to the favourable torque curve.

A “common rail” fed injection system operating at 1600 times atmospheric pressure injects precisely the right quantity of fuel into the combustion chamber at the right time to gain maximum efficiency and power.

Audi is collaborating with Shell to use their V-Power Diesel synthetic gas-to-liquid (GTL) synthetic fuel made from natural gas. It has virtually no sulphur content and is colourless and virtually odourless. It has a high cetane value, a measure of how efficiently fuel burns. The race fuel version has been specially tweaked to make it ideal for Le Mans, balancing power, endurance, fuel economy and clean emissions.

Diesel engines are more efficient than petrol, meaning fewer pit stops and lighter fuel loads, key to a race such as Le Mans. Overall CO_² emissions are also lower.

Although pipped to the pole position by Pescarolo in the qualifiers, Audi remains confident that the R10 could rewrite automotive history at Le Mans by being the first diesel car to beat a field of petrol vehicles.