The connecting rods are usually made of steel alloys like 42CrMo4, 41CrS4, SAE1141, SAE4340 etc. These are under tremendous stress from the reciprocating load represented by the piston, actually stretching and relaxing with every rotation, and the load increases rapidly with increasing engine speed.

To get high performance, we took close attention on manufacturing and inspection. To eliminate stress risers we do such techniques like grinding the edges, shot penning to relieve internal stress, balancing and magna-fluxing to find out invisible cracks which would cause the rod fail under stress. In addition to that care should be taken on the torque on bolts and nuts to the exact value specified.