In any automotive internal combustion engine, a connecting rod typically has an I-beam cross-section with two ends—an upper and a lower head, each with an opening. The piston pin, which connects the connecting rod to the piston, operates in the hole of the solid upper head. In the split hole of the lower head, a pair of connecting rod bearings is installed, and then the lower head is connected to the crankpin of the crankshaft.

Each connecting rod must be made from high-quality structural steels to withstand the high loads generated during engine operation. Additionally, it must have the following characteristics:

• High strength;
• Necessary rigidity;
• Resistance to elastic deformations;
• Dimensional stability;
• Wear resistance of the surfaces;
• Bolts and nuts for securing the lower head cap must not loosen spontaneously.

Furthermore, connecting rods supplied as spare parts should not vary significantly in weight, as this could make it difficult to achieve smooth and stable engine performance.