A flow of power as if from a turbine, a high maximum torque curve and a fascinating sound: the basic features of a perfect sports-car engine. This 5.0-litre V10 engine with its twin turbochargers is just as fascinating in the potential it offers as in its suitability for day-to-day use. Its ‘bite’ in every operating range and its unrivalled willingness to rev up to high speeds are truly impressive.
An included angle of 90 degrees between the engine’s cylinder banks helps to keep the entire car’s centre of gravity low. It makes sensible use of the available space and does not obstruct the driver’s view to the rear. A crankshaft with offset crankpins is used to ensure supreme refinement and a sporty sound.
This ten-cylinder engine has 40 valves, operated by four overhead camshafts. Both the inlet and exhaust valves have continuously variable opening periods to ensure optimum gas flow in all engine-speed ranges.
Two turbochargers driven from the exhaust and located behind the engine boost the pressure of the combustion air to a maximum of 2.0 bar before it is forced into the engine. The charge-air intercoolers are mounted above the engine. They are fed with air through an inlet on the body side and have an additional low-temperature cooling water circuit. The two oil coolers are at the side of the engine, well positioned in the airflow behind the side inlets.
As a result of these careful design measures, the engine can develop an impressive 449 kW (610 bhp). A big contribution to this formidable output is made by the direct petrol injection (FSI) system, which set new standards in the cars that won such historic victories in the 2001 and 2002 Le Mans races and in the American Le Mans Series. FSI combines outstandingly efficient power output with highly efficient combustion of the fuel.
In the Audi Le Mans quattro the ten-cylinder biturbo FSI engine is particularly pleasant on account of its willingness to rev freely and its lusty pulling power at all engine speeds. The maximum torque of 750 Newton-metres is available within an exceptionally broad engine-speed range from 1,750 to 5,800 rpm, so that unnecessarily frequent gear changes are avoided. With these basic output and torque data, the five-litre engine can catapult this two-seater car from a standstill to 100 km/h in only 3.7 seconds and continues to accelerate it until the speedometer needle reaches 200 km/h, which it does after a mere 10.8 seconds. The theoretical top speed is 345 km/h, but this is electronically governed to 250 km/h.
Despite this abundant flow of power, it is quite probable that the driver of the Audi Le Mans quattro will choose to change gear quite often at the manual selector paddles behind the steering wheel, since gear changes take only a fraction of a second and there is no clutch pedal to be operated. A short gear lever is mounted on the centre tunnel, next to the electronic parking brake control, but is used only to preselect the automatic, normal and sport modes and also to engage reverse gear.
Thanks to an electro-hydraulic system, the car can be driven away from a standstill without a clutch pedal having to be operated. In this way, the sequential-shift 6-speed gearbox offers the highest level of driver convenience as well as the dynamic gear changes expected of a sports car. The gear ratios are widely spaced, so that the driver always has the ideal gear available to make controlled use of the engine’s monumental torque.
Such a powerful Audi car naturally features the quattro permanent four-wheel drive system. The Le Mans quattro, as a leading-edge technology carrier, has a version of this legendary driveline that has been adapted to suit the car’s mid-engined layout and the associated axle-load distribution.
For optimal traction and dynamic road behaviour, the power from this mid-engined sports car’s ten-cylinder engine is normally distributed in a ratio of 40:60 between the front and rear axles. This achieves maximum agility together with optimal traction - essentials for supreme road dynamics in all conditions and on corners of varying radii.
This version of the quattro driveline, with Torsen C inter-axle differential, is of course capable of diverting engine torque to the axle at which there is more tyre grip available, in order to suppress wheelspin. Depending on the amount of grip detected, torque distribution between the front and rear axles can be varied continuously from 20 : 80 to 70 : 30 percent.