Lightweight power cell unit

A method, comprising:

• moving a piston assembly of a power cell unit in a reciprocating manner, the piston assembly having a piston crown and a piston skirt, the piston crown including a ring belt portion extending circumferentially about a combustion bowl and at least one boss portion extending downward from the combustion bowl;
• transferring a gas load generated by the reciprocating movement of the piston assembly directly from the piston crown to a connecting rod of the power cell unit through a contact between a bottom surface of the at least one boss portion and a surface of a funnel of the connecting rod;
• and
• transferring an inertial load from at least one of the piston crown and the piston skirt to at least one piston pin that rotatably secures the piston assembly to the connecting rod.

A power cell unit, comprising:

• a piston assembly;
• a connecting rod;
• and
• at least one piston pin configured to connect the connecting rod with the piston assembly;
• wherein the piston assembly engages with the connecting rod during reciprocal movement of the piston assembly such that a gas load generated from downward movement of the piston assembly substantially transfers directly from the piston assembly to the connecting rod, and approximately no more than an inertial load generated from upward movement of the piston assembly is transferred to the at least one piston pin;
• and
• wherein a compression height ratio of a compression height of the power cell unit to a diameter of the piston assembly ranges from 20% to 37%.