Porsche tests the feasibility of a hydrogen V8 engine at the Nürburgring

Hydrogen is one of the potential power sources for future engines being investigated. However, in most cases, its development is aimed at commercial vehicles with relatively low power, approximately 68 CV per liter of displacement, which is insufficient for, say, automobiles with specific characteristics.

High-performance hydrogen engine

Porsche is looking for an alternative, as Vincenzo Bevilacqua, Senior Engine Simulation Expert at Porsche, points out: "This is insufficient for the passenger car sector." As a result, we created a prototype combustion engine with the goal of matching the power and torque of today's high-performance gasoline engines. Simultaneously, we set the target of attaining low fuel usage while keeping pollutants at the same level as ambient air.

After everything is said and done, Porsche begins with an existing 4.4-liter eight-cylinder engine, however, the test was not quite accurate: According to this specialist, the starting point for our investigation was an existing 4.4-liter eight-cylinder petrol engine, or rather, its digital data set, because we completed the entire study digitally utilizing engine performance simulators.

A greater compression ratio, hydrogen-adapted combustion, and, most critically, a new turbocharging system were among the changes undertaken.

According to Bevilacqua, turbochargers must produce about double the air mass as in gasoline engines for clean hydrogen combustion; nevertheless, the lower temperature of the exhaust gases reduces their energy.

This issue cannot be remedied with traditional turbochargers, which is why Porsche Engineering investigated four different turbocharger supercharging solutions, some of which were inspired from competition. All were aided by electricity.

According to Bevilacqua, each turbocharging method had distinct advantages and drawbacks in the experiments. The best option is determined by the needs of the hydrogen engine in question.

Finally, following many testing, a turbocharging system with parallel compressors was selected, allowing for a coaxial configuration of two compressor stages, which are powered by the turbine or the supporting electric motor through a shared shaft. According to the engineer, air goes through the first compressor, is cooled in the intercooler, and then re-compressed in the second stage. This engine produces roughly 598 horsepower (440 kW), which is comparable to the original gasoline engine. It was tested, although virtually, in a premium vehicle weighing 2,650 kilos on the Nordschleife Nürburgring track.

The test was carried out using a digital twin, which is a computer replica of the actual vehicle. They claim that the automobile had great promise with a lap time of 8 minutes and 20 seconds. It had a top speed of 261 km/h. It should be noted that the burning of hydrogen produces no hydrocarbons, carbon monoxide, or particles. As a result of extensive testing, the engine approach was modified to ensure the cleanest combustion possible. The goal was to keep gross emissions low by using extremely lean and hence colder combustion, which allows for the elimination of an exhaust gas after-treatment system.

According to Matthias Böger, engineer Engine Simulation Specialist at Porsche Engineering, nitrogen oxide emissions were substantially below the limitations stipulated by the Euro 7 standard (in effect from 2025), near to nil across the engine map.

Aside from having nearly no emissions, the hydrogen engine has a great fuel economy, both in the WLTP homologation cycle and in other cycles, thanks to its lean combustion.

The practicality of an engine with these features, according to those in charge of the project, may be equivalent to that of a gasoline engine. Although the supercharging system and a series of mechanical components linked with hydrogen are more complex and hence more expensive, the after-treatment of exhaust gases is not required, as it is in a gasoline propellant that claims to comply with the Euro 7 standard.