King Bearings Announces Oversized XPG Main Bearings For Subaru EJ

King Bearings Announces Oversized XPG Main Bearings For Subaru EJ
King has developed oversized main bearings to reduce repair costs and improve reliability


King Engine Bearings has just released two new oversized main bearing kits for the Subaru EJ series engines. Due to the nature of the Subaru split-block boxer engine design,  where two halves of the engine are fastened together around the crankshaft, there can often be distortion or misalignment even on new engine blocks. This distortion can lead to uneven main bearing wear and occasionally bearing failure due to insufficient lubrication and overloading of the bearing surface material. Main line bore distortion can also occur in new blocks that have been assembled using high strength case fasteners, which are common in racing and high performance engine builds.



When an EJ engine requires a repair to remedy a main line bore distortion issue, the labor involved can be tedious and therefore very expensive. The machinist would have to remove material from both sides of the split-block’s mating surfaces and  bore or hone back to a STD housing bore measurement so that a standard OD bearing can be utilized. This process also requires and extreme amount of precision and can cause a change in the crankshaft centerline to deck surface distance that would need to be compensated for.



King’s new oversize bearings can reduce machining and labor costs and therefore lower the overall repair costs passed on to the vehicle owner. Additionally, more damaged engine blocks can be restored and reused while still being able to provide a precise and perfect rebuild. This is particularly helpful for racers with engine blocks that are previously modified in other ways, and would have to be scrapped if not for the ability to use King’s oversized main bearings to repair main line distortion. 


Oversize Outside Diameter Main Bearing Sets for Subaru EJ Series Engines: 

King PNHousing Bore Spec'sCrankshaft Undersizes
MB5739XPG  +.002″2.5217″-2.5225″ (64.051mm-64.071mm)STD, STDX, .026
MB5740XPG  +.005″2.5247″-2.5255″ (64.127mm-64.147mm)STD, STDX, .026




Read all about King Bearings in MotoIQ's Extreme Engine Tech S52 and K24 builds. 


For more information on the King Engine Bearings complete line of engine bearings, visit


About King Engine Bearings
Founded in 1960, King Engine Bearings is a world-class developer and manufacturer of high technology engine bearings for automobiles, light and heavy-duty trucks, marine, aviation, standby power and other types of internal combustion engines. King's only product is engine bearings. As a result of its specialization and focus, the company is recognized for producing the highest quality engine bearings available in the market today. The King line includes OEM replacement rod, main, cam bearings, and thrust washers and its special range of racing bearings. King’s extensive coverage of domestic and import engine bearings ships from its main distribution center in Cedar Grove, N.J. and 11 other factory branch warehouses. For more information, visit



Leave a Reply

Your email address will not be published. Required fields are marked *