This four-stroke single-cylinder diesel engine model features a transparent compact design with dual operation modes—manual hand-cranking or external power supply—to clearly demonstrate the complete Otto cycle of intake, compression, power, and exhaust strokes, making it an ideal teaching apparatus for middle school physics thermodynamics experiments. This diesels engine model is and tested for durability and function in real worlds use and conditions. Compact design, making it convenient for demonstration. Simple and reliable in general applications. The Experimental Model sets can be used to explain the basic structure and working principle of a four a stroke single cylinder diesels engine. Our combustion engine model is suitable for middle school physics course experiment teaching. Two ways of using, manual or connecting power supply.