A new and unique four-stroke i.c. engine without the conventional crankshaft is described. A lobe plate, which moves the piston according to predictable laws of motion, transforms reciprocating movements into rotative ones.The idea derives from the observation of the structure and functioning of pumps with axial plunger whose units plungerod, moving, holds closely to a plate whose angle of inclination determins the motion characteristics and the value of the stroke itself. The new solution introduces a more efficient method of transferring power from a piston to a driveshaft. A peculiar configuration of engine block has been designed, in which pistons, purposely designed, transmit power to a purposely shaped disk. Each piston follows the shape of this disk during the revolutions. The cam provides a broad range of engine displacements using only one block, varying only the piston laws of motion according to the different disks used. A prototype has been planned, its characteristics are shown, and the theoretical analysis has been performed.