King MB5840SI Performance Main Bearing Set for Gen 3 HEMI | King SI-Series Bearings

The King MB5840SI Main Bearing Set is engineered to provide exceptional durability, precise oil clearance control, and long-lasting reliability for Gen 3 HEMI engine builds. As part of King’s highly respected SI-Series lineup, these premium tri-metal main bearings are designed to support everything from stock rebuilds to aggressive naturally aspirated, supercharged, turbocharged, and nitrous-assisted combinations. Whether you’re refreshing a daily-driven 5.7L HEMI, assembling a forged 6.4L stroker, or building a four-digit horsepower 6.2L Hellcat engine, selecting high-quality main bearings is critical to maintaining crankshaft stability, proper lubrication, and overall engine longevity. The MB5840SI bearing set offers engine builders the confidence needed when assembling high-performance engines expected to endure substantial loads and demanding operating conditions.

Main bearings serve as one of the most important components inside an internal combustion engine, supporting the crankshaft while maintaining a thin protective layer of oil between moving surfaces. Inferior bearings or worn factory components can contribute to oil pressure fluctuations, increased friction, accelerated crankshaft wear, and potentially catastrophic engine failure. King’s SI-Series bearings utilize a proven tri-metal construction featuring a hardened steel backing, copper-lead intermediate layer, and precision-engineered overlay material that offers improved fatigue resistance and excellent embeddability characteristics. This design helps accommodate minor contaminants while maintaining superior load-carrying capability under extreme cylinder pressures.

Performance enthusiasts frequently turn to King Bearings because of their consistent manufacturing tolerances and reputation for producing bearings capable of supporting both moderate street builds and professional-level race engines. The MB5840SI bearings are designed to provide reliable oil film retention and improved resistance to fatigue, making them especially beneficial for applications subjected to elevated RPM levels, increased boost pressure, or repeated drag strip launches. Their precision manufacturing process helps engine builders achieve desired bearing clearances while reducing the need for extensive fitting or additional machining procedures during assembly.

Whether your goal is restoring a factory-spec HEMI, building a weekend warrior, or developing a competition engine for drag racing, road course events, or standing-mile competition, investing in premium bearings can significantly impact long-term engine reliability. King Bearings have become a preferred choice among professional engine builders because they deliver dependable performance without compromise. Pairing high-quality bearings with proper machining practices, balanced rotating assemblies, and adequate lubrication systems can help maximize engine efficiency and extend service life even in severe-duty environments.

The King MB5840SI Main Bearing Set is an excellent choice for enthusiasts and builders seeking race-proven bearing technology backed by decades of engineering expertise. Be sure to browse our Engine Bearings & Bottom End Components category for additional rod bearings, thrust washers, piston rings, crankshafts, fasteners, and performance engine assembly components designed to support your next Gen 3 HEMI build.

Specifications & Features
Manufacturer: King Engine Bearings
Product Name: MB5840SI Main Bearing Set
Manufacturer Part Number: MB5840SI
Product Series: SI-Series
Product Type: Main Bearing Set
Construction: Tri-Metal Bearing Design
Bearing Material: Steel Backing, Copper-Lead Intermediate Layer, Precision Overlay
Color: Metallic Finish
Standard Size Configuration
Designed for Improved Oil Retention
Excellent Fatigue Resistance
High Load Capacity
Precision Manufacturing Tolerances
Suitable for High RPM Applications
Compatible with Forced Induction Builds
Ideal for Naturally Aspirated and Nitrous Applications
Excellent Embedability Characteristics
Professional Engine Builder Preferred
Vehicle Compatibility:
Dodge Challenger 5.7L HEMI
Dodge Challenger 6.4L HEMI
Dodge Charger 5.7L HEMI
Dodge Charger 6.4L HEMI
Dodge Charger Hellcat 6.2L Supercharged HEMI
Jeep Grand Cherokee Trackhawk 6.2L Supercharged HEMI
RAM 1500 TRX 6.2L Supercharged HEMI
Chrysler 300 5.7L and 6.4L HEMI
Engine Compatibility:
5.7L Gen 3 HEMI
6.1L Gen 3 HEMI
6.2L Supercharged HEMI
6.4L / 392 HEMI
Year Compatibility: Varies by Engine Platform
Weight: Approximately 1.2 lbs.
Dimensions: OEM Main Bearing Dimensions
Installation Difficulty: Advanced
Professional Installation Recommended: Yes
Intended Use: Engine Rebuilds, Performance Builds, Street Applications, Drag Racing, Road Racing, High-Horsepower Forced Induction Engines