ACL 4B1956H-.25 Race Rod Bearing Set +0.25mm Honda D15 D16 D16Y D16Z Civic CRX

Vehicle Fitment

• 1988-2000 Honda Civic (EF/EG/EH/EJ/EK series) - D15B, D15Z, D16A, D16Y, D16Z series (1.5L/1.6L SOHC Inline-4)
• 1988-1991 Honda CRX (EF series) - D15B, D16A6 (1.5L/1.6L SOHC Inline-4)
• 1993-1997 Honda Del Sol (EG/EH series) - D15B, D16Z6, D16Y (1.5L/1.6L SOHC Inline-4)
• Also fits B18A (USA), B20B4, B20Z2 (Honda CR-V/Integra LS non-VTEC) where crankpin journal dimension matches
• JDM ZC SOHC and DOHC variants sharing D-series journal dimensions

Fitment Notes

• The .25 suffix designates this as the +0.25mm oversize bearing set - intended for use when the crankshaft rod journals have been ground 0.25mm undersize during a rebuild. The thicker wall restores correct running oil clearance on a more significantly reground crankshaft.
• Do NOT use on a stock, unground crankshaft. For standard journal diameter, use 4B1956H-STD. For crankpins ground 0.025mm undersize, use 4B1956H-.025.
• Covers all D15B/D15Z and D16A/B/W/Y/Z engine code variants that share the same crankpin journal diameter - the most common US-market applications are D16A6, D16Y5, D16Y7, D16Y8, and D16Z6.
• Always measure crankshaft rod journal diameter with a micrometer before selecting bearing size. Confirm actual 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 forced-induction demands of built Honda D-series engines.
• Hardened steel backing on all rod bearings improves structural support of the bearing lining and maintains crush under high sustained loads and temperatures.
• High-strength overlay plate with reduced thickness provides improved fatigue resistance compared to OEM-spec bearings - critical in turbocharged D-series builds and high-revving naturally aspirated applications.
• 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 Honda D-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 the 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: 4B1956H-.25
• Product Line: ACL Race Series
• Application: Connecting Rod Bearings
• Engine Compatibility: Honda D15B/D15Z variants (1.5L SOHC); Honda D16A/D16B/D16W/D16Y/D16Z variants (1.6L SOHC); Honda ZC; B18A (USA), B20B4, B20Z2 (matching journal only)
• Crankshaft Size: +0.25mm Oversize (for crankpins ground 0.25mm undersize)
• Shaft (Crankpin) Diameter: 44.730-44.750mm (1.7610-1.7618 in)
• Tunnel (Housing Bore): 48.000-48.020mm (1.8898-1.8906 in)
• Maximum Wall Thickness at Crown: approx. 1.624mm (0.0639 in)
• Maximum Overall Length: 18.5mm (0.728 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 - +0.25mm Oversize

Product Description

The ACL Race Series 4B1956H-.25 connecting rod bearing set is the +0.25mm oversize option for Honda's D-series inline-4 engine family - the broad 1.5L and 1.6L SOHC engine lineup powering the Honda Civic, CRX, and Del Sol across multiple generations from 1988 through the early 2000s. This oversize set is selected when the crankshaft rod journals have been ground 0.25mm undersize to address surface wear or scoring, restoring correct oil clearance on the reground crank. A single set covers all D15B/Z and D16A/B/W/Y/Z variants sharing the same crankpin journal diameter.

The D-series remains one of the most popular platforms for budget-friendly Honda builds, particularly turbocharged D16Y/Z applications where bearing quality directly impacts longevity under boost. Built on ACL's Race Series tri-metal platform, these bearings deliver superior fatigue resistance and oil film stability over OEM Honda shells. Always verify crankshaft journal diameter with precision measurement and confirm clearances at assembly before final torque. Sold as a complete set of 8 shells for one engine.