It's not so much news as anticipation. Porsche is talking up its complicated petrol-electric hybrid 919 Le Mans racer ahead of the Big French Race next month, and some of what it has to say is fascinating. For those frustrated by the fact that F1 has become effectively a spec formula, the variety at Le Mans is staggering. All three top teams have gone for an entirely different setup. Audi has a four-wheel-drive diesel flywheel hybrid, Toyota a rear-drive petrol battery hybrid while Porsche's solution is also using petrol engines and batteries; though it additionally gets extra energy from heat recuperation.
How does that work? Rather like a turbocharger actually. There's a little impeller turbine in the exhaust of the car, which spins up as the exhaust gases race past it. That turbine turns a generator that puts electrical charge back into the batteries. Porsche claims that, alongside its brake energy recuperation system, the 919 is the only Le Mans racer this year that can harvest energy for its batteries under braking and acceleration. Clever stuff.
Alexander Hitzinger, Porsches LMP1 programme manager (LMP1 is the class at Le Mans in which the 919 is racing - it's the big boy class, basically...), has been telling us all about the 919 and he told us why Porsche abandoned the flywheel hybrid system it had been racing in recent years in a 911 GT3 car in favour of batteries for the 919. "The recuperation of kinetic braking energy at the front axle has great potential with the axle load being dynamically shifted to the front when you brake, so a system that exploits this was a logical step," he explained. "In favour of this solution we gave up a KERS on the rear axle. If you start with a naturally aspirated engine, KERS is the only option you have. But using turbo charging gave us another option, which is why we opted for using the energy from exhaust gases from the turbo charger."
"Developed in cooperation with Porsche Engineering," stresses Hitzinger, "so this knowhow benefits future hybrid vehicles." Hitzinger also looked into flywheel storage and supercapacitors, so called ultracaps, but found lithium ion batteries to be the best compromise. "But only if," he adds, "the right cell technology is available to provide a very high power density with relatively high storage capacity."
The amount of electrical energy each driver can use per lap at Le Mans delivered as a boost is limited. The rules specify four classes of energy levels ranging from two to eight mega joules (MJ). Porsche has registered the 919 Hybrid for the 6MJ category, which means that the LMP1 prototype can use exactly 1.67 kilowatt hours (kWh) of energy per 13.629 km long lap on the "Circuit des 24 heures", since 3.6 mega joules is equivalent to 1 kilowatt hour (kWh). But what does this mean in real terms?
In 2013 the Le Mans winner covered 348 laps. Calculated over the same distance the new 919 Hybrid generates and uses 581.2 kilowatt hours (kWh) - an electric output that would run a 60-Watt light bulb for a staggering 9,687 hours. Or in other words: with the energy the LMP1 Porsche prototype recuperates during the Le Mans race you could cover 4,576 km in the most efficient electric car that is currently available in the compact class, the new Volkswagen e-Golf - which would take you across the USA from coast to coast, from New York to Los Angeles.
The 919 is something of a technical marvel, with its unique V4 engine (kept small to save weight, V-layout to make it an integral part of the chassis) and clever hybrid setup. Porsche has already scored podium finishes in World Endurance Championship (WEC) events at Silverstone and Spa, but Le Mans will be the toughest challenge of all and with the company's record there, the world will be expecting something spectacular. It really is a Porsche racing car too - the project is being managed entirely in-house, whereas rivals Audi and Toyota contract out the running of their teams to Joest and Oreca respectively.
Anything else?
There are only three weeks to wait until we find out who's come up with the best technical solution - The Le Mans 24hrs kicks off on Saturday the 14th of June.