Monday, August 8, 2016

How to Win at Le Mans, Porsche 919 Style

Curious what it takes to beat the world elite at the grueling 24 Hours of Le Mans? Sixty years of motorsports experience and 17 victories at the Circuit de La Sarthe, combined with the latest hybrid powertrain and aerodynamic technologies, were keys to Porsche’s success in 2016. Of course, the German team's smart strategies were only looking good enough for a second-overall finish until Toyota suffered ill fortune in the last few minutes of the race.Thanks to Porsche’s willingness to provide a peek under the 919 hybrid’s skin, we’re able to share these details about the car’s engineering.The primary power producer is an aggressively turbocharged and intercooled 2.0-liter, four-cam V-4 gasoline engine, which is restricted to 500 horsepower by current FIA (Fédération Internationale de l'Automobile) rules. The 250-horsepower-per-liter specific output is, of course, impressive, but Porsche claims this is also the most efficient internal-combustion engine it has ever produced.Engine output is routed to the rear wheels through a seven-speed transaxle fitted with a locking differential.Two generators charge a pack of lithium-ion storage batteries to provide energy for the 919’s 800-volt electrical system. Inside the pack, which is mounted low in the middle of the carbon-fiber-composite tub, there are hundreds of liquid-cooled cells, each 2.7 inches long and 0.71 inch in diameter.Sixty percent of the Porsche 919 hybrid's electrical energy comes from a motor/generator attached to the front axle. The remaining 40 percent comes from a turbine-powered generator spun by a portion of the engine’s exhaust gas. The driver may tap the 400 horsepower that’s available to drive the front wheels by pressing a steering-wheel button. This regeneration strategy is employed during every application of the brakes.Additional rules restrict exactly how much urge the driver may exploit for acceleration. No more than 1.8 liters of fuel and 2.2 kWh of electrical energy may be consumed per lap at Le Mans. It’s the driver’s task (with help from engineers monitoring the data from the car via telemetry) to achieve maximum speed without exceeding these limits. With 900 or more horsepower propelling less than 2000 pounds of race car (plus 16.5 gallons of fuel and the driver), performance is, of course, exceptional: zero to 60 mph in 2.2 seconds, zero to 120 mph in 4.8 seconds, and a top track speed of 211 mph.The Porsche 919 hybrid program was announced in 2012, with the race car revealed the following year, and it has been phenomenally successful. In 2014, at its competition debut in the 6 Hours of Silverstone (England), a Porsche finished third behind two Toyota hybrids. (A second Porsche DNF'd.) At Le Mans that year, Porsche scored an 11th-place overall finish. Last year, the 919 won six races, including Le Mans from the 24 Hours' pole position. Two other Porsches finished, in second and fifth. This year, 919s scored first-place—averaging more than 134 mph for 24 hours—and 13th-place finishes at Le Mans. Pity Team Toyota, which has now logged five second-place finishes in France without a victory.What’s it all for? Beyond the addition to Porsche’s groaning trophy case, lessons learned at Le Mans—specifically the 800-volt electrical architecture—will transfer to a pure-electric Porsche production car due before the end of this decade.
from Car and Driver Blog http://www.caranddriver.com/flipbook/how-to-win-at-le-mans-porsche-919-style


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