Reader Response Draft 3: Porsche 919 Hybrid Power Unit

The 2017 Porsche 919 Hybrid LMP1 is powered by an advanced power unit with an internal combustion engine, a turbocharged 2.0-litre V4, and an electric system (Goodwin, 2017). The 2 engines combined produce a total output of over 900 HP. Fuel is directly injected into the ICE, which produces 500 HP. The rest comes from 2 energy recovery systems (ERS) that are stored in lithium-ion batteries (Brownell, 2017). The ERS-K (Kinetic) recovers almost 60% of the energy generated during the deceleration at the front wheel, which provides all-wheel drive functionality whenever necessary. The ERS-H (Heat) creates energy by utilising the heat from exhaust gases (Porsche AG, 2017). According to Goodwin in 2017, with the regulations set by the governing body of the Le Mans 24, the race car was allowed to consume up to 8 MJ of the energy recovered by the ERSs to cover as many laps as possible in the 24 hours of racing. This made the 919 Hybrid the most energy-efficient car on the track.

With the combined ICE and electric motor (ERSs) in the power unit, the Porsche 919 Hybrid is one of the most technologically advanced cars to dominate the WEC and Le Mans 24-hour. 

The ICE of the 919 Hybrid 2017 is Porsche’s most efficient 2.0-litre V4 engine (Porsche AG, 2017). It represents the time and effort spent building and refining it over the years Porsche participated in the Le Mans and WEC. The term ‘V4’ is derived from the 4 cylinders of the engine, that are placed 2-per-row in a V-shaped configuration. It delivers an output of approximately 500 HP (Perkins, 2019).  Mike Fernie explains in his video that this configuration is exceptional due to its compact size, compared to others such as the V6 and the V8. Using the V4 was an excellent choice as it provided a rigid structure to the vehicle, due to its compact size and placement near the rear axle. The 90-degree configuration of the cylinders also played a part in providing rigidity and structure. This minimised vibrations or forces acting on the engine/car, but not fully. Another special feature the ICE possesses is the ability of DFI, also known as Direct Fuel Injection. Instead of fuel delivered into the combustion chambers via intake, it is directly injected into the chambers via the cylinders (Pratte, 2016). This provided better consistency and control of the fuel injected into the engine, allowing the 919 to operate smoothly compared to other cars in the Le Mans and WEC.  

Working with the ICE are 2 Energy Recovery Systems in an electric motor. These are the Kinetic ERS and the Heat ERS. Both systems are stored in the lithium-ion battery, which powers the electric engine (Goodwin, 2017). The ERS-K comes into action when the car brakes. During braking, a generator is used to recover and store the energy the battery uses. Goodwin states that on average, 80% of the energy recovered via the ERS-K is converted into energy, which increases the acceleration when activated. The ERS-H is activated when the 919 Hybrid is under extreme stress from engine overuse (Newsroom, 2016). As such, this causes the exhaust energy to be used up fast. A small turbine in the vehicle's exhaust is implemented to recover it. The turbine stores the recovered energy in the same generator that houses the recovered kinetic energy. These 2 systems increased the car’s total output to 900 HP and up to 8MJ of energy use per lap under the Le Mans regulations (Porsche AG, 2017). This proves that without the ERSs, Porsche would have to depend on a whole new ICE to maintain similar performance levels as it did with its hybrid system. Thus, highlighting the contribution of the ERSs to the 919 Hybrid’s dominant performance in the Le Mans and WEC.

Despite the dominance of the 919 Hybrid in the Le Mans and WEC, hybrid power units in endurance racing are not always perfect. A concern was the reliability of the ICE and electric motor under extreme conditions during the race. In its earlier renditions during the Le Mans, Porsche’s team driver Timo Bernhard had been driving for 20 out of the 24 hours, after which he handed over the car to his teammate, Mark Webber. The car continued in the lead for another 20 minutes before retiring from the race completely (Porsche Engineering, 2014). The cause was damage to the ICE due to its overuse in the 20 hours, relying solely on the electric motor to return to the pit stop before retiring (Porsche Engineering, 2014). 

In conclusion, the combination of the 2 energy recovery systems and the unique features of the V4 turbocharged ICE contributed to the success and dominance of the Porsche 919 Hybrid in the WEC and Le Mans. Refining the power unit over the years, this combination made the car one of the most technologically advanced and energy-efficient cars to grace the racing industry. 

 

References

Goodwin, G. (2017, March 31). Porsche’s 2017 919 hybrid in detail. dailysportscar.com. Porsche’s 2017 919 Hybrid In Detail

Porsche, A. (2017, March 31). The new Porsche 919 Hybrid. Porsche Newsroom. The new Porsche 919 Hybrid

Loewenberg, G. (2017, March 31). Porsche officially unveils the 919 Hybrid for 2017. The Drive. Porsche Officially Unveil The 919 Hybrid For 2017

Stuttgart. (2015, June 30). Porsche AG: Porsche Technologies of the future in a test of endurance - porsche USA. Porsche HOME: Porsche technologies of the future in a test of endurance - Porsche USA. Porsche technologies of the future in a test of endurance

Perkins, C. (2019, February 14). Why V-4 engines are brilliant, and why you never see them in Cars. Why V-4 Engines are Brilliant, And Why You Never See Them In Cars. Why V-4 Engines are Brilliant, And Why You Never See Them In Cars

Fernie, Mi. (2019, February 13). Why V4 engines are so rare and which cars use them - Mike’s Mechanics. YouTube. Why V4 engines are so rare and which cars use them - Mike's Mechanics

Pratte, D. (2016, November 11). Direct injection:how it works and why it’s a game changer (for better and for worse). Speed Academy. Direct Injection:How It Works And Why It’s A Game Changer (For Better And For Worse) | Speed Academy

Porsche Engineering. (2014). Download - Porsche Engineering. https://www.porscheengineering.com/filestore/download/peg/en/magazine-2014-02/default/e9e20c16-b6b3-11e4-a19d-001a64c55f5c/Download.pdf  (Page 35)