King Engine Bearings MB7089XP025 XP Series Tri-Metal Main Bearing Set - 0.25mm

The King Engine Bearings MB7089XP0.25 is a high-performance XP Series tri-metal main bearing set engineered for the Volkswagen VR6 2.8L engine. Sized at +0.25mm oversize, this set is purpose-built for performance and race engine rebuilds running forged steel aftermarket crankshafts under sustained high-load conditions.

At the heart of the XP Series is King's proprietary pMax Black™ tri-metal construction — a surface-hardened lead-tin-copper overlay electroplated onto a copper alloy substrate. This advanced metallurgical treatment modifies the overlay's molecular structure, creating a nano-scale fatigue-resisting shield that delivers 17% greater fatigue resistance and an overlay hardness 24% higher than conventional tri-metal race bearings. Load capacity in the overlay reaches 10,200 psi, while the intermediate copper layer is rated at 17,000 psi.

XP Series Key Features:

• pMax Black™ Tri-Metal Construction — Enhanced copper lead tri-metal with nickel barrier and SecureBond™ adhesion layer for superior structural integrity between bearing layers
• Bull's Eye Tolerance™ — Industry-leading wall thickness variation of ±0.0001", ensuring precise oil clearance and consistent fit across all shells in the set
• EccentriX™ Medium Eccentricity — Optimized eccentricity geometry for improved oil wedge formation, stable hydrodynamic lubrication, and optimal load distribution
• Enlarged, Chamfered Oil Holes — Main bearing shells feature oversized, chamfered oil feed holes for improved oiling under high RPM and load
• Half-Groove Upper Shell Design — Mains are half-grooved to preserve full load capacity in the lower shell where peak bearing loads occur
• Narrowed Design — Shells are narrowed to clear large-radius crankshaft fillets common on aftermarket and billet crankshafts
• SecureBond™ Adhesion — Micro-etch bonding process improves multi-layer adhesion and structural integrity between the overlay, intermediate, and backing layers

Recommended Applications:

• High-load, long-duration racing: circle track, off-road, offshore boat racing
• Performance street and track builds using forged or billet steel crankshafts
• Engine rebuilds requiring a +0.25mm (metric) crankshaft undersize

King Engine Bearings has specialized exclusively in engine bearings since 1960, manufacturing every bearing in-house from raw alloy casting through overlay plating and quality inspection. The XP Series represents the pinnacle of their racing line, combining advanced metallurgy with precision geometry to support the highest loads and RPM demands of today's performance engines.