A glimpse to the hybrid powertrain of Porsche’s 919 racing car

July 21, 2016 // By Christoph Hammerschmidt
During the forthcoming weekend, Porsche’s Le Mans prototype 919 Hybrid will have its first and only appearance in Germany. A good opportunity for a look under the bonnet of the reigning world champion in the WEC Class.

With the 919 Hybrid, Porsche has opened new technologies for race vehicles. The two-litre four cylinder turbo engine (Porsche claims that this is the most efficient internal combustion engine the company ever built), utilizes two different energy recuperation systems. During braking, it converts kinetic into electric energy in the front axle. In addition there is a split exhaust system that accommodates the turbo charger – and a second turbine that converts surplus energy into electric energy. This turbine features high energy efficiency at low weight. The converted kinetic energy from the front axle accounts for 60% of the total electric energy gained through recuperation, the energy extracted from the exhaust system to 40%.

 

The electric energy from these two processes is stored in a lithium-ion battery and used to drive an electric motor if desired. The driver can activate this energy and turn it into additional thrust at any time through the push of a button. The electric motor offers not much less power than the combustion engine: 294 kW electric power add to 368 kW of conventional power. The electric motor drives the front axle while the combustion engine drives the rear axle.

 

The use and interplay of these two different energy sources requires a rather sophisticated strategy. In each braking phase, the battery collects electric energy. During the Grand Prix circuit on the Nürburgring race track which has a length of 5.148 km (3.2 miles) this is the case ahead of every curve, a total of 17 times. The tighter the curve the more intensive is the braking. Once he passed the apex of the curve, the driver typically wants to activate the stored energy immediately. He does so by pushing the “boost” button.

 

On long straights, when the vehicle drives along at the highest speed possible, it again recuperates energy, because during such high-speed phases the turbine in the exhaust pipe is generating a