King Engine Bearings MB5270XP XP-Series pMaxBlack Tri-Metal Main Bearing Set

The King Engine Bearings MB5270XP is a race-grade XP-Series crankshaft main bearing set engineered for high-performance and competition applications. Built around King's proprietary pMaxBlack™ tri-metal construction, this set delivers exceptional load capacity and fatigue resistance far beyond what conventional performance bearings can offer.

pMaxBlack™ Tri-Metal Technology:

• High-copper overlay: The pMaxBlack™ overlay contains 5% copper — significantly more than the 2–3% found in standard performance bearings — resulting in a 29% increase in overlay hardness (18.1 HV) and an overall 24% increase in load capacity, reaching up to 10,200 psi
• Nano-scaled hardening process: A proprietary nano-scaled hardening process modifies the overlay's molecular structure, creating a black fatigue-resistant shield that protects under extreme loads and high RPM
• Enhanced intermediate layer: The intermediate layer tin content is increased to 4.5% (versus 2–3% in standard race bearings), making it 22% harder at 115 HV with a load carrying capacity of 17,000 psi
• SecureBond™ adhesion: A micro-etch surface preparation process strengthens the bond between tri-metal layers, significantly reducing the risk of delamination under extreme load or metal-to-metal contact conditions

XP-Series Geometric Features:

• Bull's Eye Tolerance™: Wall thickness tolerances held to an industry-leading ±0.0001 in., ensuring precise, consistent clearances shell-to-shell
• Narrowed design: Bearings are narrowed to clear large-radius aftermarket crankshafts
• Enlarged, chamfered oil holes: Improves oil flow and lubrication at high engine speeds
• Medium eccentricity: Enables optimum load distribution and improved oiling across the bearing surface

Set Contents & Application:

• Designed for race and high-performance forced-induction applications
• Intended for use with forged steel aftermarket crankshafts
• Race-only application — not recommended for street-driven or low-RPM engines

The MB5270XP is purpose-built for builders who demand maximum reliability and load-handling capability in demanding race environments. King Engine Bearings has been a specialist in precision engine bearings since 1960, manufacturing every bearing in-house to ensure consistent quality and accuracy.