For the new E38 MAN stationary gas engine series, the development goal from the very beginning was low-NOx capability combined with market-leading characteristics in terms of mechanical efficiency and power density. Another premise was that the cast part of the diesel cylinder head of the new engine series had to be carried over for the gas application. To achieve these goals, simulations and bench tests went hand in hand: Through extensive studies in 1D CFD simulation, the feasibility limits in terms of mean effective pressure with at the same time low end-of-compression cylinder temperatures were determined using appropriate valve timings and a high compression ratio of the single stage turbo charger. The interaction of the valve timings with the different piston bowl shapes was investigated in the 3D CFD simulation, so that the test campaign on the single-cylinder test bench could be significantly reduced. Atkinson timings (LIVC—late intake valve closing) combined with a squish piston contour proved to be particularly attractive overall, as they allowed a high level of turbulent kinetic energy to be maintained over the entire compression and duty cycle. Further fine-tuning of the turbo charger matching, final optimization of the passive pre-chamber spark plug design and the application for different operating points was carried out on the multi-cylinder-engine. The final engine design enables a compact combustion at low raw NOx emissions and a moderate heat dissipation from the combustion chamber. This results in best in class efficiencies and a superb mean effective pressure.