Porsche brought their 911 GT3 R Hybrid to this side of the pond, to compete in last weekend’s Petit LeMans at Road Atlanta. The car started from the 43rd spot, but managed an 18th place finish despite two unscheduled pit stops during the event. The car, entered into the GTH class for experimental cars, was co-driven by Timo Bernhard, Mike Rockenfeller and Romain Dumas. Their goal wasn’t so much to win the event, but rather to develop as much information as possible on Porsche’s hybrid drive system under racing conditions. The data gathered will be applied to future racing efforts, and eventually to Porsche road cars as well.
The hybrid drive system in the Porsche 911 GT3 R Hybrid differs substantially from those used in production cars like the Toyota Prius. The Porsche system is a Kinetic Energy Recover System (KERS), similar to what was developed for Formula One racing in the 2009 season. The GT3 R Hybrid has two electric motors mounted at the front wheels; under braking, these motors act as generators. The energy created is transmitted to a KERS flywheel unit, which sits where the passenger seat would be in an ordinary car. The flywheel, which can spin at up to 40,000 RPM, stores the kinetic energy recovered from braking, but only for a limited amount of time (around eight seconds). Exiting a corner, a driver can use the energy stored in the flywheel to power the front wheel motors, creating a short burst of additional horsepower or reducing the amount of throttle needed (and hence, fuel consumed) to regain speed.