Where is the wrist pin usually offset on the piston?

The wrist pin in a piston is typically offset towards the major thrust face. This design is intentional and serves several important purposes. The major thrust face is the side of the piston that experiences the most force during combustion and the downward stroke. By offsetting the wrist pin toward this side, engineers can help manage the forces acting on the piston and improve the engine's overall efficiency and performance.

The offset helps minimize the side loads on the piston that can cause wear and enhance stability during movement within the cylinder. This design consideration also aids in the smooth operation of the piston as it moves up and down, reducing the risk of piston slap and extending the life of engine components.

In contrast, other positions for the wrist pin, like equally centering it, would not provide the same mechanical advantages and could result in adverse effects such as increased vibration or excessive wear on the components. Positioning it towards the minor thrust face or at the bottom of the piston would also lead to inefficiencies and a less effective handling of the forces experienced during engine operation.