ACL 4B8170H-STD Race Rod BearingSet Standard Mazda L3 2.3L MZR Mazda 3 6 Tribute

Vehicle Fitment

• 2004-2009 Mazda 3 (BK/BL) - L3-VE 2.3L DOHC 16v MZR (Naturally Aspirated)
• 2003-2008 Mazda 6 (GG/GH) - L3-VE 2.3L DOHC 16v MZR (Naturally Aspirated)
• 2001-2006 Mazda Tribute - L3-VE 2.3L DOHC 16v MZR
• 2003-2008 Ford Escape - L3 Duratec 2.3L DOHC 16v (naturally aspirated variants)
• 2006-2009 Ford Fusion - L3 Duratec 2.3L (where applicable)

Fitment Notes

• This set is for the naturally aspirated L3-VE (MZR) 2.3L engine only. The turbocharged L3-VDT DISI engine (Mazdaspeed 3, Mazdaspeed 6, Mazda CX-7) uses different connecting rods and a different crankpin journal diameter - those applications require either 4B8171H (no notch) or 4B8172H (with notch). Do NOT use 4B8170H in any L3-VDT turbo application.
• Standard (STD) crankshaft rod journal diameter - for use with stock or unworn crankpins at factory diameter only. For reground crankshafts, use 4B8170H-.025 (+0.025mm) or 4B8170H-.25 (+0.25mm) as appropriate.
• An HX extra-clearance variant (4B8170HX-STD) is also available for builders targeting approximately 0.025mm (0.001") additional running clearance at standard journal diameter.
• 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 demands of performance-built L3-VE applications.
• 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 - a meaningful upgrade for any L3 rebuild where bearing longevity and reliability are priorities.
• 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 L3-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: 4B8170H-STD
• Product Line: ACL Race Series
• Application: Connecting Rod Bearings
• Engine Compatibility: Mazda L3-VE 2.3L DOHC 16v MZR (Naturally Aspirated); Ford L3 Duratec 2.3L (naturally aspirated)
• Crankshaft Size: Standard (STD - Unground)
• Shaft (Crankpin) Diameter: 49.980-50.000mm (1.9677-1.9685 in)
• Tunnel (Housing Bore): 53.025-53.045mm (2.0876-2.0884 in)
• Maximum Wall Thickness at Crown: 1.500mm (0.0591 in)
• Maximum Overall Length: 17.0mm (0.669 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

Product Description

The ACL Race Series 4B8170H-STD connecting rod bearing set is the standard-size performance replacement for the Mazda L3-VE 2.3L DOHC MZR inline-4 - the naturally aspirated version of Mazda's L-series engine powering the Mazda 3, Mazda 6, Mazda Tribute, and related Ford Escape/Fusion applications. Co-developed with Ford as the "Duratec" family, the L3-VE is an all-aluminum DOHC engine known for its smooth power delivery and widespread use across Mazda's and Ford's compact and midsize vehicle lineup through the mid-2000s.

Built on ACL's Race Series tri-metal platform, these bearings deliver superior fatigue resistance, bearing retention, and oil film stability over the OEM aluminum-alloy shells that are prone to accelerated wear in higher-mileage or performance applications. A worthwhile upgrade for any L3-VE rebuild. Note that the turbocharged L3-VDT (Mazdaspeed, CX-7) requires a different part number. Always confirm clearances at assembly. Sold as a complete set of 8 shells for one engine.