Connecting rod materials tested include 2024, 7075, 7079, & 7068 aluminums; 6AL4V titanium; AISI O-1; AISI A-2; CPM-3V tool steel; M-2 tool steel; & AISI-S7 shock resisting tool steel. Connecting rods made of S-7 (oil hardened & tempered) survived many test runs beyond 32,000+ rpm, but completely failed when pushed to 38,000 rpm. The one titanium rod standing on its side used the Perry designed oil pump hole through the middle of a bushed rod to help improve sleeve bearing lubrication. A slot, cut into side of the rod allowed crankcase lubrication to enter on each engine revolution. This was also done to aluminum rods. There was only a slight improvement in performance. In the upper left hand corner is the first steel roller rod (not hardened with pressed in hardened race) which survived 6 runs at 32,000 rpm before failing . The pressed in race turned, closing off the oil lubricating holes. It used a hardened berillium copper retainer. In the middle row, the six rods on the right are made of 6AL4V Titanium. This super alloy does not transfer heat, & requires a seperate material for the bearing surface. These two things make it unsuitable for connecting rods in large motors.
