Audi’s Powertrain Racing Prowess

Gary S. Vasilash

It was Vorsprung durch Technik in spades this past weekend at the 12-hour Sebring race, as two LMP1 Audis—R18 e-tron quattros—battled back and forth, had 20 lead changes from one to the other, until they finished one-two, with a 7.69-second separation.

12h Sebring 2013

Audi R18 e-tron at Sebring

What’s notable is that this is the first time that a hybrid has won at Sebring. What is also notable from an engineering point of view (although more than a little acknowledgement has to be given to the various drivers who have piloted Audi vehicles*) is that in 2006, an Audi R10 TDI took the checked flag, the first time a diesel won the race.

A hybrid and a diesel.

Seems like Audi has a handle on relevant powertrain technology, both on the track and on the road.

As for the setup on the R18 e-tron quattro: the rear axle is powered in a conventional manner with a 3.7-liter, 490-hp V6. The front axle is electrically powered. It uses two driveshafts and a motor generator unit (MGU); energy is retrieved from an electric flywheel accumulator.  A lithium-ion battery is used.

The accumulator is located alongside the driver in the cockpit. Energy is obtained during braking. The flywheel is made with carbon fiber; it spins in a high vacuum. The energy is used to drive the front wheels when a drive comes out of a turn and starts acceleration, but, in keeping with the regulations, can be used only when the vehicle going above 120 km/h. The MGU for the 2013 R18 e-tron produces >2 x 80 kW. The 2012 R18 e-tron MGU produces 2 x 75 kW.

Interestingly, the car that was victorious at Sebring was a 2012 model, with the 2013 taking second place.

(And incidentally, as the American Le Mans Series and the GRAND-AM Series are merging to form the “United SportsCar Racing” series, and as there will be no more LMP1 cars permitted to run in it, this may have been the last time Audi appears at Sebring.)

*The winners of the 2013 Sebring race are Marcel Fässler, Benoît Tréluyer and Oliver Jarvis.