Prevent premature head gasket failure on bigger power engines! The Evolution Powersports XR Series CA-625 11mm direct replacement Polaris XPT head studs are for those wanting the ultimate strength for high horsepower engine builds. Manufactured by ARP using their proprietary Custom Age alloy, the XR series head stud is the strongest head stud available anywhere. Custom Age 625 alloy typically equals or exceeds the clamping force of ~2mm larger 8470 Chromoly fastener in a smaller package. For the XP Turbo/Pro XP engine where there is not much material in the block to enlarge the stud significantly, these 11mm Custom Age 625 studs are the ideal solution. These head studs will keep your engines head sealed for the boost pressure required to produce 300-400 horsepower.
Why the EVP XR Series CA-625 studs are superior to other studs on the market:
- The 11mm (stock) OD is the ideal size to maximize clamping force without sacrificing block integrity
- Made from ARP CA-625 alloy - This super-alloy has superior fatigue cycle life, tensile strength and toughness and is rated to 260,000 psi tensile strength. For comparison, a typical 8470 chromoly stud is roughly 170,000 psi.
- Machined ball end allows the stud to bottom out in the case without losing any thread engagement.
- Includes head studs, nuts, and washers for the ultimate direct replacement head stud kit