The development process of 2-stroke engines is characterized by limited CFD investigations in combination with long-term development phases on the test bench with high prototype costs. To reduce the costs and to realize shorter development time together with a higher prediction quality of the engine potential, a higher implementation level of 1D and 3D simulation tools into the development process is necessary.This publication outlines the 1D simulation methods in the layout phase of GDI combustion processes of 2-stroke engine categories. By means of conceptual investigations, the demands, the potential and the limits of 1D CFD simulation methodology are defined. Using a comparison between 1D and 3D or 1D/3D coupled simulation methods the limits of solely 1D simulation are shown. For advanced simulation tasks with a higher demand for prediction quality, the entire engine is simulated in 1D, whereas special parts of the engine design are simulated in a 3D model.The limits of the pure 1D simulation can be shifted by the use of additional information from experimental and 3D simulation methods leading to parameter sets for the 1D simulation. With the rebuild of a state of the art 2-stroke engine the prediction quality is exemplarily shown and therewith the application of this method is demonstrated. By the use of test bench results of this engine type, the quality of the 1D simulation strategy is verified.