The engine process is the thermodynamic process around the actual energy conversion in the internal combustion engine. This includes the high-pressure process, the gas exchange, but also the supercharging. The process is therefore the core of every engine, and even after 150 years of development, there is sufficient need for research.

The working process determines the power, fuel consumption and emissions of each internal combustion engine. However, the extensive and complex other parts of modern powertrains, such as the hybrid system and exhaust aftertreatment, have somewhat overshadowed the basic engine and its process in the past. This is mainly due to the fact that a further improvement of the process is sometimes quite expensive, which is mainly due to systems to further increase the variability. However, stringent CO₂ legislation requires taking this potential into account, as well as using more sophisticated systems than before. Examples of such systems are variable compression ratio, variable timing or extended expansion.

The investigation of engine processes requires more than most other topics a strong linkage between experiment and simulation. At the test bench, careful cylinder pressure indication, accurate fuel consumption measurement and emissions measurement are the basis. All test benches in the division Propulsion Systems have the necessary state-of-the-art measurement technology.

The potential contribution of the simulation is manifold, ranging from zero-dimensional process analysis and simulation to one-dimensional gas exchange simulation (1D-CFD) to the three-dimensional simulation of fluid dynamics (3D-CFD). The FVT has all the necessary tools at its disposal.

Numerous projects have been used in the past to build up a comprehensive experience with the investigation of engine processes. The sound assessment of engine processes requires a very basic approach with a strong involvement of the theory and an intensive link between measurement and simulation.

An example of a successful campaign is the extended expansion project.