It is no secret that Stirling engines are great for teaching physics. They are not the only type of engine you can use in the classroom though. Take the WOLFBSUH Toyan FS-S100AS Methanol Engine: it is a 4-stroke engine that fits in the palm of your hand. As it runs on Methanol, your students will be able to clearly see how various engine parts work.
This engine has a speed of up to 13,500rpm. It has an aluminum alloy and steel construction. The fuel tank has 90mL capacity, which lasts up to 40 minutes.