Internal combustion engine test benches allow to simulate the operation of an engine under various conditions and are essential in engine development in automotive industry. Models of such test benches are often used in the design and improvement of the quality of test bench controls and to simulate their behavior. Therefore, the paper summarizes a modeling procedure based on a simple model structure. In particular, the individual components of a test bench are described and their models are combined. A torque observer is used to compensate the lack of torque measurements. Finally, a model for a test bench equipped with a heavy duty engine is determined and validated with measurements.