OVERVIEW

The King SI-Series Main Bearing Set (MB5745SI0.25) is engineered as an upgraded OE-replacement main bearing set for Subaru FA20/FA24 and Toyota 4U-GSE/FA24D engines requiring a 0.25mm undersize fitment. Constructed with King's lead-free silicon-aluminum bi-metal alloy, this set provides precise oil clearance and journal protection when assembling engines with re-ground crankshaft main journals.

FEATURES

• 0.25mm Undersize Journal (+0.25mm Bearing Wall Thickness): Engineered specifically for crankshaft main journals re-ground 0.25mm smaller than standard diameter. Features a +0.25mm thicker bearing wall to restore exact OEM oil clearances.
• Silicon-Aluminum Bi-Metal Alloy: Advanced lead-free material featuring 2.5–3% silicon for exceptional surface hardness and wear resistance.
• Optimized Oil Delivery: Precision-grooved halves ensure reliable oil distribution across main journals under all engine operating temperatures.
• High-Micro Finish Consistency: Manufactured to strict wall thickness tolerances to eliminate clearance variance across main caps.

WHAT IS INCLUDED

• (1) King Engine Bearings SI-Series Main Bearing Set (Complete 10-Piece Main Bearing Set - 0.25mm Undersize)

SPECIFICATIONS

• Part Number: MB5745SI0.25 (MB5745SI 0.25)
• Series: SI-Series (Bi-Metal OE-Replacement / Upgrade)
• Material: Aluminum-Silicon Bi-Metal Alloy
• Crankshaft Journal Size: 0.25mm Undersize
• Bearing Shell Wall: +0.25mm Oversized Thickness
• Warranty: 12 Months
• Installation Time: Professional Engine Assembly Required
• Difficulty: Advanced / Engine Overhaul

FITMENT

• 2013-2020 Toyota 86 / Scion FR-S / Subaru BRZ (ZN6 / ZC6 - FA20 / 4U-GSE Engine)
• 2022-2026 Toyota GR86 / Subaru BRZ (ZN8 / ZD8 - FA24 / FA24D Engine)
• Replaces OEM Part Numbers: 12209AA650, 12209-AA650

WARNING: California Proposition 65 — This product contains chemicals known to the State of California to cause cancer, birth defects, or other reproductive harm. Intended for competition / off-road use only.