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In the competition for the powertrain of the future the internal combustion engine faces tough challenges. Reduced environmental impact, higher mileage, lower cost and new technologies are required in order to maintain its global position both in public and private mobility. For a long time, researchers have been investigating the so called Homogeneous Charge Compression Ignition (HCCI) that promises a higher efficiency due to a rapid combustion - i.e. closer to the ideal thermodynamic Otto cycle - and therefore more work and lower exhaust gas temperatures. Consequently, a rich mixture to cool down the turbocharger under high load may no longer be needed. As the combustion does not have a distinguished flame front it is able to burn very lean mixtures, with the potential of reducing HC and CO emissions. However, until recently, HCCI was considered to be reasonably applicable only at part load operating conditions.

Over the past years, the question as to what may be the powertrain of the future has become ever more apparent. Aiming to improve upon a given technology, the internal combustion engine still offers a number of development paths in order to maintain its position in public and private mobility. In this study, an innovative combustion process is investigated with the goal to further approximate the ideal Otto cycle. Thus far, similar approaches such as Homogeneous Charge Compression Ignition (HCCI) shared the same objective yet were unable to be operated under high load conditions. Highly increased control efforts and excessive mechanical stress on the components are but a few examples of the drawbacks associated with HCCI. The approach employed in this work is the so-called Spark Assisted Compression Ignition (SACI) in combination with a pre-chamber spark plug, enabling short combustion durations even at high dilution levels.