Abstract: An exemplary piston pin for a power cell unit having a piston assembly and a connecting rod may include an elongated body. The elongated body generally may be configured to rotatably secure the piston assembly and the connecting rod in a manner such that no more than approximately an inertial loading generated from an upward movement of the piston assembly is transferred to the elongated body.

Abstract: A power cell unit may include a piston assembly having a piston crown and a piston skirt. The piston crown may include a ring belt portion extending circumferentially about a combustion bowl and at least one boss portion extending downward from the combustion bowl. The power cell unit may also include a connecting rod having an elongated portion and a funnel portion, and at least one piston pin configured to connect the connecting rod with the piston assembly. A bottom surface of the at least one boss portion may engage with a corresponding surface of the funnel portion such that a gas load is substantially transferred directly from the piston crown to the connecting rod during downward motion of the piston assembly, and such that only inertial loading from the piston crown and/or piston skirt is transferred to the piston pin during upward motion of the piston assembly.