Piston Thrust Side vs Non-Thrust Side — True Engine Dynamics Explained ➤ Piston Thrust Side and Non-Thrust Side Inside an internal combustion engine such as a typical internal combustion engine, the piston does not simply move perfectly straight up and down. Because the connecting rod is mounted at an angle during most of the crankshaft rotation, a side force is generated. This side force causes the piston to press harder against one side of the cylinder wall. That is where the concept of thrust