ACL 4B1606HX-STD Race Rod Bearing Set STD +0.001" Audi VW 1.6 1.8T 2.0L EA113

Vehicle Fitment

• 1983-2001 Audi A3, A4, A6, TT, 80, 90, 100 - 1.6L (1595cc), 1.8L (1781cc, incl. 1.8T Turbo), 2.0L (1984cc) Inline-4
• 1983-2003 Volkswagen Polo, Caddy, Golf, Jetta, Passat - 1.6L (1595cc), 1.8L (1781cc, incl. 1.8T Turbo), 2.0L (1984cc) Inline-4

Fitment Notes

• This bearing set is for connecting rods WITH a locating notch (tang) - the EA113 Gen 1 engine family. Later Audi/VW engines from approximately 2000 onward use connecting rods WITHOUT a notch and require a different bearing set (4B1609HX-STD). Verify your connecting rod type before ordering.
• The HX designation indicates extra oil clearance: the bearing wall is approximately 0.013mm thinner per shell compared to the standard 4B1606H-STD set, providing approximately 0.025mm (0.001") of additional running clearance at standard crankshaft journal diameter - without any crankshaft grinding.
• Recommended for high-performance, high-boost, or high-RPM Audi/VW builds where slightly increased oil film thickness is desired for improved bearing protection under elevated cylinder pressures and temperatures.
• For standard oil clearance at stock journal diameter, use 4B1606H-STD. For reground crankshafts, use the appropriate oversize H set: 4B1606H-.025, 4B1606H-.25, or 4B1606H-.50.
• Always confirm actual running clearance with Plastigage or a dial bore gauge after assembly - do not rely solely on bearing size designation.
• 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 performance-built Audi and Volkswagen inline-4 engines.
• HX extra-clearance wall thickness provides approximately 0.025mm (0.001") of additional oil clearance versus the H-STD set, increasing oil film volume between the crankpin and bearing surface for improved lubrication under extreme load.
• Hardened steel backing on all rod bearings improves structural support of the bearing lining and maintains crush under high sustained loads.
• High-strength overlay plate with reduced thickness provides improved fatigue resistance compared to OEM-spec bearings - critical in turbocharged 1.8T and performance 2.0L builds operating above stock power levels.
• 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 Audi/VW 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: 4B1606HX-STD
• Product Line: ACL Race Series
• Application: Connecting Rod Bearings (With Notch / Tang)
• Engine Family: Audi/VW EA113 Gen 1 - 1.6L, 1.8L (incl. 1.8T), 2.0L Inline-4
• Crankshaft Size: Standard (STD - Unground)
• Oil Clearance Designation: HX - Extra +0.025mm (+0.001") clearance vs. H-STD
• Shaft (Crankpin) Diameter: 47.758-47.778mm (1.8802-1.8810 in)
• Tunnel (Housing Bore): 50.600-50.619mm (1.9921-1.9929 in)
• Maximum Wall Thickness at Crown: approx. 1.392mm (0.0548 in)
• Maximum Overall Length: 19.00mm (0.748 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 Notch

Product Description

The ACL Race Series 4B1606HX-STD connecting rod bearing set is the extra-clearance performance option for Audi and Volkswagen EA113 Gen 1 inline-4 engines - the 1.6L, 1.8L (naturally aspirated and 1.8T turbocharged), and 2.0L four-cylinder family powering a wide range of Audi and VW models from 1983 through the early 2000s. Sharing the same standard crankpin journal diameter as the 4B1606H-STD, the HX variant uses a slightly thinner wall (~0.013mm per shell) to deliver approximately 0.025mm (0.001") of additional running oil clearance without any crankshaft modification. This increased clearance supports a thicker hydrodynamic oil film between the crankpin and bearing surface - a meaningful advantage in high-boost 1.8T builds or any application where a more liberal oil clearance specification is preferred.

A critical fitment note: this bearing is designed for connecting rods with a locating notch (tang) - characteristic of EA113 Gen 1 hardware. Later engines from approximately 2000 onward use a no-notch rod design requiring the 4B1609HX-STD instead. Always verify rod type before ordering. Built on ACL's Race Series tri-metal platform, these bearings deliver superior fatigue resistance and oil film stability over OEM shells. Always confirm actual running clearance at assembly. Sold as a complete set of 8 shells for one engine.