What is sleeve valve engines?

Sleeve valve engines are a type of internal combustion engine where the valves are situated within the engine block rather than in the cylinder head. The valves are cylindrical sleeves that slide over ports in the engine block to open and close the intake and exhaust ports. This design eliminates the need for external moving valve mechanisms, resulting in a simpler and more reliable engine.

Sleeve valve engines were popular in the early 20th century, particularly in aircraft and luxury cars, but have become less common in modern engines. However, they still have some benefits such as reduced turbulence during combustion, which can lead to better fuel efficiency and smoother operation.

There are several types of sleeve valve engines, including three- and four-stroke designs, as well as radial and inline configurations. Some notable examples of sleeve valve engines include the Bristol Hercules engine used in World War II-era airplanes and the Daimler-Benz DB 601 used in the Messerschmitt Bf 109 fighter plane.