ACL Bearings 4B4390-STD Race Series Connecting Rod Bearing Set Standard Size

The ACL Bearings 4B4390-STD is a high-performance connecting rod bearing set designed specifically for Ford Duratec 2.0L (121ci) and Mazda LF MZR 1998cc inline-four engines. This Race Series bearing set features standard size specifications and is engineered to deliver motorsport-proven reliability in high-performance applications.

Key Features:

• Tri-layer metal construction with hardened steel backing designed to withstand high RPM conditions, high stress loads, and elevated temperatures
• Hardened steel backs on rod bearings improve support of the bearing lining and assist with bearing retention in the housing
• Tight consistent wall tolerances help maintain consistent oil clearances
• Increased eccentricity compensates for bore distortion at high RPM and assists in the formation of hydrodynamic oil films
• Elimination of flash plating on bearing backs improves heat transfer and maximizes grip between bearings and housing
• Advanced materials with improved dynamic thickness, heat conduction, and oil distribution make ACL a leading bearing manufacturer

Technical specifications include a maximum shaft size of 47mm (1.85 inches), tunnel size ranging from 50.025mm to 50.045mm, and wall thickness at crown of 1.503mm. These bearings feature identical bearing halves and are manufactured from F781 bearing material with an overall length of 16.25mm.

ACL Race Series bearings are recognized as a premier brand throughout the motorsports world, serving as standard components in race engines from drift racing to NASCAR, IHRA, and NHRA competitions. These bearings are ideal for tuning and engine upgrades where higher bearing capacity and better quality than standard bearings are required.