The design of a high-speed combustion engine begins with determining the rotational vibration position of the machine. To calculate the critical speeds, a precise understanding of the engine's design is required. Typically, multiple assumptions about the engine are made during the design of a machine, and the validity of these assumptions is verified through subsequent vibration calculations. The aim of this work was to minimize this time-consuming activity to the essential minimum. To achieve this, the engine dimensions and weights of a large number of gasoline and diesel engines were compiled in charts, taking into account the design type and number of cylinders. This allows the designing engineer to quickly gain an overview of the dimensions of already constructed machines and to make the initial assumptions.