ARP Ultra-Torque allows builders to torque fasteners within 5% of their required preload on the first pull, virtually eliminating preload scatter, and ensures exacting fastener-to-fastener preload consistency.
Due to frictional inconsistencies with oil, moly, and other lubricants it takes multiple cycles of torquing the bolt, loosening it, and tightening it again to obtain the required preload or stretch. Typically, when a fastener is first tightened, friction is at its highest point and the preload value or stretch is low. As the fastener is cycled numerous times the friction decreases and the preload increases. This phenomenon is called preload scatter. Extensive testing has shown preload scatter to be as much as 20-40% on a new fastener, depending on the lubricant used. With ARP Ultra-Torque, a fastener need only be torqued once to get within 5% of ideal preload and remain consistent through all subsequent cycles (from race-prep machining through final assembly and subsequent rebuilds).
Moreover, given the inconsistencies of ordinary lubes, it is quite possible for adjacent head bolts or studs to have vastly different preloads. This scatter can cause bore distortion, hamper piston ring sealing, and lead to poor head gasket sealing. Preload differences in connecting rods and main caps can cause uneven bearing loading. Its easy to see how ARP Ultra-Torque can actually help you build a more powerful, reliable engine!