Main Bearings

The King Racing MB4058XP is a set of main bearings engineered for the demanding conditions of high-load, long-duration racing, including circle track, off-road, and off-shore applications that require steel crankshafts. These bearings are part of the XP high-performance series, developed to meet the increasing load capacities demanded by successful race engine builders. Constructed with an enhanced tri-metal copper lead composition, these bearings feature a nickel barrier and SecureBond adhesion, providing superior stability between the top and intermediate layers. This construction offers a 15% to 30% greater load capacity compared to traditional bearings. Additionally, a 0.0005" metallurgically enhanced and hardened performance overlay is applied to withstand greater loads and resist surface fatigue. The main bearings are designed with a 1/2 groove for uncompromised lower shell load capacity. King Racing's XP series incorporates pMax Black, a unique tri-metal structure that is 24% harder than conventional tri-metal race bearings. Combined with the XP geometric features, these bearings are an ideal choice for performance racing applications utilizing forged steel aftermarket crankshafts that produce high loads for extended periods.