Abstract: The present invention refers to a four-cycle, internal combustion engine se pistons have variable strokes, the adjustment of the piston displacement and of the fuel consumption being automatically and continuously realized as a function of the drive shaft load torque.The engine uses an axially annular equidistant location of the cylinders in a cylinder block, comprising an odd number of pistons whose connecting rods are connected, by means of ball joints, with a central oscillating ball, diametrically penetrated by a drive shaft, the ball being sustained by two journal bearings mounted in a gliding bracket. The drive shaft is provided at one of its ends with two oppositely mounted sides that can move along two grooves formed in the inner surfaces of a fork provided at the end of an output shaft, another drive shaft end being coupled directly to a planetary reduction gear box for the control of the intake and exhaust valves.