The efficiency and reliability of hydrogen internal combustion engines (H2-ICE) are highly impacted by pre-ignition and hydrogen slipping into the crankcase. Thus, piston and piston rings are key components of the PCU and play an important role in the development of hydrogen combustion engines. Pre-ignition can be caused by oil entering the combustion chamber. To stabilize the hydrogen combustion, oil induced pre-ignition must be avoided. However, to support H2-ICE efficiency, the blow-by needs to stay at the lowest possible level to reduce the amount of unburned hydrogen entering the crankcase. The sealing capability of the PCU is highly challenged by the substantial difference between the physical and chemical properties of hydrogen when compared to diesel or natural gas fuels. The translation of the physical impact is mandatory to deduce the correlations of the dynamic gas flow and gas pressure conditions to the sealing behavior of piston and piston rings. The paper will show how the ring dynamic simulation by PRiME3D® dedicated to hydrogen combustion enables the development of the PCU sealing system for H2-ICE. The outcome of a holistic development approach including advanced simulation, product development and testing that target reduced oil-induced pre-ignition and lowest H2-slip will be demonstrated.