The present invention relates to a combustion engine system having a balance arm, first and second sets of opposed combustion cylinders, and a set of opposed worked devices. The balance arm has a pivot point, and is configured so that an exploitable energy is taken from a kinetic energy of the balance arm. The first set of working combustion cylinders being interconnected by a common first piston rod that is connected to the balance arm. The second set of working combustion cylinders being interconnected by a common second piston rod that is connected to the balance arm so that the pivot point is between the first and second piston rods. The worked devices are interconnected by a common worked piston rod that is connected to the balance arm so that the worked devices are between the first and second sets of combustion cylinders.