An engine piston with opposed piston pin bosses depending from the head of the piston and laterally spaced apart. A piston pin is secured within openings in the bosses, such openings being aligned transversely whereby the piston pin also is disposed transversely of the piston. The pin is formed with a plurality of eccentrically disposed holes of selected lengths extending longitudinally of the piston pin. Such holes are spaced predetermined distances apart and are arranged one above another while preferably occupying in whole less area than the solid area of the pin adjoining said holes. These holes in certain instances may be circular in shape and in number ranging for examples from two to six. In other instances the holes may be either rectilinear, oval or approximately triangular in shape and vary in number such for example as three or four thereof.