CP-Carrillo connecting rods are fully machined from a proprietary 4330m alloy forging for strength and durability. Rods are available with 2 types of bolts: The standard WMC-H7 (H11) bolt with a UTS of 220ksi and our upgraded CARR-S7 (MP35N) bolt with a UTS of 285ksi. The CARR upgraded bolt is a good choice if planning on revving the engine higher than 8500rpm. All our bolts are manufactured with asymmetrical threads, each thread has a slightly different design than the previous giving the bolts an evenly distributed thread engagement. This helps increasing the clamp load and fatigue life of the fastener.