ACL 4B1972HXD-STD Race Rod Bearing STD +0.001" Dowel Honda K20A2 K24A RSX Civic

Vehicle Fitment

• 2002-2006 Acura RSX Type-S (K20A2, 2.0L DOHC 16v i-VTEC, 200 hp) - with aftermarket dowel-pin connecting rods
• 2002-2005 Honda Civic Si EP3 (K20A2, 2.0L DOHC 16v i-VTEC, 197 hp) - with aftermarket dowel-pin connecting rods
• 2003-2012 Honda Accord (K24A, 2.4L DOHC 16v i-VTEC) - with aftermarket dowel-pin connecting rods
• 2002-2014 Honda CR-V (K24A, 2.4L DOHC 16v i-VTEC) - with aftermarket dowel-pin connecting rods
• 2003-2011 Honda Element (K24A, 2.4L DOHC 16v i-VTEC) - with aftermarket dowel-pin connecting rods
• All K20A2 and K24A applications using aftermarket connecting rods equipped with a dowel-pin bearing locating hole

Fitment Notes

• The "HXD" designation combines two features: the HX extra oil clearance (bearing wall approximately 0.013mm thinner per shell vs. HD-STD, providing ~0.025mm / 0.001" additional running clearance at standard journal diameter) and the "D" dowel hole in the lower bearing shell for aftermarket connecting rods with dowel-pin bearing retention.
• Do NOT use in OEM Honda K-series connecting rods - factory rods use a tang/notch locator and require 4B1972H-STD or 4B1972HX-STD. Always verify your connecting rod's bearing retention design before ordering. Using a dowel-hole bearing in a tang-style rod (or vice versa) can result in improper bearing seating and engine failure.
• For dowel-hole rods at standard oil clearance, use 4B1972HD-STD. For tang/notch OEM rods with extra clearance, use 4B1972HX-STD. For tang/notch OEM rods at standard clearance, use 4B1972H-STD.
• For reground crankshafts with dowel-hole rods, use 4B1972HD-.025 or 4B1972HD-.25 as appropriate.
• Always confirm actual running clearance with Plastigage or a dial bore gauge after assembly.
• Sold as a complete set of 8 bearing shells - sufficient for one full 4-cylinder engine build.

Features

• Tri-metal construction: copper-lead alloy lining bonded over a hardened steel backing, with a high-strength overlay plate - engineered for the high-RPM and high-boost demands of built K20A2 and K24A engines running performance aftermarket connecting rods.
• HX extra-clearance wall thickness provides approximately 0.025mm (0.001") of additional oil clearance versus the HD-STD set, increasing oil film volume between the crankpin and bearing surface for improved lubrication under extreme load - particularly valuable in boosted or sustained high-RPM K-series builds.
• Dowel hole in lower bearing shell precisely machined to align with the dowel pin in compatible aftermarket connecting rods, ensuring correct bearing orientation and retention throughout engine operation.
• Hardened steel backing on all rod bearings improves structural support of the bearing lining and maintains crush under the high sustained loads expected in race and high-power K-series builds.
• High-strength overlay plate with reduced thickness provides improved fatigue resistance compared to OEM-spec bearings - critical in forced-induction and high-revving K-series builds.
• Increased bearing crush and tighter wall tolerances ensure consistent, secure seating in the connecting rod housing bore, reducing the risk of bearing spin.
• Enlarged ID chamfers on bearing edges accommodate the larger fillet radii found on performance and aftermarket K-series crankshafts.
• 3/4-groove design optimizes oil supply to the rod journal and maximizes load-carrying surface area across the bearing face.
• Elimination of flash plating on bearing backs improves heat transfer and maximizes grip between the bearing shell and rod housing bore.
• Increased eccentricity compensates for bore distortion at high RPM and assists in the formation of a stable hydrodynamic oil film under load.

Specifications

• Part Number: 4B1972HXD-STD
• Product Line: ACL Race Series
• Application: Connecting Rod Bearings - With Dowel Hole in Lower Shell + Extra Oil Clearance
• Engine Compatibility: Honda/Acura K20A2 (1998cc DOHC 16v i-VTEC); Honda K24A (2354cc DOHC 16v i-VTEC)
• Rod Retention Type: Dowel Pin (aftermarket connecting rods only - NOT for OEM Honda K-series rods)
• Crankshaft Size: Standard (STD - Unground)
• Oil Clearance Designation: HX - Extra +0.025mm (+0.001") clearance vs. HD-STD
• Shaft (Crankpin) Diameter: 47.980-48.000mm (1.8890-1.8898 in)
• Tunnel (Housing Bore): 51.004-51.024mm (2.0080-2.0088 in)
• Maximum Wall Thickness at Crown: approx. 1.488mm (0.0586 in)
• Bearing Material: Tri-Metal Copper-Lead Alloy / Hardened Steel Backing
• Quantity: Set of 8 Shells (complete engine set)

Included Components

• 8x Race Series Connecting Rod Bearing Shells - Standard Size, Extra Oil Clearance (HX), With Dowel Hole in Lower Shell

Product Description

The ACL Race Series 4B1972HXD-STD connecting rod bearing set is the most fully specified option for Honda/Acura K20A2 and K24A engines running aftermarket connecting rods - combining the "HX" extra oil clearance (+0.025mm / 0.001" vs. standard) with the "D" dowel hole in the lower shell for dowel-pin rod retention. This set is the choice when a builder is running premium aftermarket K-series connecting rods (Carrillo, Eagle, Brian Crower, Manley, and similar) that locate the bearing via a dowel pin rather than a tang, and simultaneously wants the more liberal oil clearance specification preferred for high-boost, high-RPM, or sustained track use.

Built on ACL's proven Race Series tri-metal platform, these bearings deliver superior fatigue resistance and oil film stability over OEM shells. The combination of extra clearance and dowel-hole retention makes this the go-to set for serious K-series race builds where both precision bearing location and optimized lubrication clearance are required. Always verify connecting rod bearing retention type before ordering and confirm clearances at assembly. Sold as a complete set of 8 shells for one engine.