Compression ignition engines and methods of the type wherein the engines operate with one cylinder used as a compression cylinder and a second cylinder used as a combustion cylinder. The engines have all cylinders configured so as to be able to operate as a compression cylinder or a combustion cylinder. In the method of operation, a cylinder may switch its operation between being a compression cylinder and then operate a combustion cylinder. Switching the operation between compression and combustion operation results in an even temperature distribution within the engine, and eliminates the need for special cooling requirements, facilitating retrofit of existing engines. Also use of an air storage tank allows all cylinders to operate as combustion cylinders for short bursts of power. Various other features are disclosed.