abyssin3 wrote:But on the other hand, on this type of engine, the compression ratio is stable, since there is no rise of the cylinder.
"there is no ascent of the cylinder." : I'm a ball in motors but that seems really weird to me: on a standard 4-stroke (or even a 2-stroke), the cylinder not moving. It's the piston that goes up and down. This is also the case in this engine by the way.
So, either you confused the terms "cylinder" and "piston", or I did not understand anything.