ACL 1M2505H-STD-1 Race Main Bearing Set Grade 1 Nissan VR38DETT GT-R R35 09-24

Vehicle Fitment

• 2009-2024 Nissan GT-R R35 - Premium, Track Edition, Nismo (3.8L VR38DETT Twin-Turbo V6)

Fitment Notes

• The STD-1 suffix designates this set for use with a Grade 1 (Version 1) VR38DETT cylinder block. Nissan stamps each GT-R block at the factory with a main bearing grade code reflecting the as-machined main tunnel size. Grade 1 tunnels are slightly larger than Grade 0, requiring a correspondingly thicker bearing shell (+0.005mm per shell vs. STD-0) to achieve factory oil clearance targets.
• Before ordering, verify your block's main bearing grade stamp. Using the wrong grade will result in incorrect oil clearance - too tight risks bearing failure; too loose risks journal damage and reduced oil pressure.
• For Grade 0 blocks: use 1M2505H-STD. For Grade 2 blocks: use 1M2505H-STD-2. For Grade 3 blocks: use 1M2505H-STD-3. Individual bearings can also be mixed across grades for fine clearance tuning.
• Covers all four main crankshaft journals - set of 8 shells (upper + lower per journal). Thrust washer sold separately.
• For standard (unground) crankshaft journal diameter only. Undersize variants are available for reground cranks.

Features

• Tri-metal construction: copper-lead alloy lining bonded over a hardened steel backing, with a high-strength overlay plate - engineered to withstand the extreme loads and high-RPM demands of the VR38DETT in stock and built configurations.
• Hardened steel backing on all main bearings provides structural support under sustained high-load and high-temperature conditions, maintaining crush and bore roundness in the aluminum GT-R block.
• High-strength overlay plate with reduced thickness improves fatigue resistance compared to OEM-spec bearings - critical in high-boost and high-RPM applications where bearing loads are substantially elevated.
• Increased bearing crush and tighter wall tolerances ensure consistent, secure seating in the main tunnel bore, reducing the risk of bearing rotation.
• Enlarged ID chamfers accommodate the larger crankshaft fillet radii found on the VR38DETT and aftermarket performance crankshafts.
• 3/4-groove upper bearing design optimizes oil supply to the main journals and maximizes load-carrying surface area.
• Elimination of flash plating on bearing backs improves heat transfer through the shell and maximizes grip between the bearing and the main tunnel bore.
• Increased eccentricity compensates for bore distortion at high RPM and assists in maintaining a stable hydrodynamic oil film under load.

Specifications

• Part Number: 1M2505H-STD-1
• Product Line: ACL Race Series
• Application: Crankshaft Main Bearings
• Engine Compatibility: Nissan VR38DETT 3.8L DOHC Twin-Turbo V6
• Block Grade: STD-1 (Grade 1 / Version 1 Block)
• Wall Thickness at Crown: 2.505-2.509mm (0.0986-0.0988 in)
• Crankshaft Journal Diameter: 64.951-64.975mm (2.5571-2.5581 in)
• Tunnel (Housing Bore) Diameter: 69.993-70.017mm (2.7556-2.7566 in)
• Bearing Width: 20.00mm (0.787 in)
• Bearing Material: Tri-Metal Copper-Lead Alloy / Hardened Steel Backing
• Crankshaft Size: Standard (Unground)
• Quantity: Set of 8 Shells (4 Upper + 4 Lower - complete engine set)

Included Components

• 8x Race Series Main Bearing Shells - STD-1 Grade (4 Upper + 4 Lower)

Product Description

The ACL Race Series 1M2505H-STD-1 main bearing set is a high-performance replacement for the crankshaft main bearings of the Nissan VR38DETT - the hand-assembled 3.8L twin-turbo V6 that powers the R35 GT-R from 2009 through 2024. Unlike rod bearing sets where a single size fits all, the VR38DETT main bearings use a factory grading system: each block is stamped with a grade code reflecting the exact as-machined main tunnel size, and the corresponding bearing grade is chosen to achieve the correct oil clearance at assembly. The STD-1 set is the correct choice for Grade 1 blocks - a wall thickness of 2.505-2.509mm per shell provides the right fit for slightly larger-than-minimum Grade 1 tunnels.

Built on ACL's proven Race Series tri-metal platform, these bearings deliver meaningfully superior fatigue resistance, crush, and oil film maintenance compared to OEM shells - making them a standard upgrade for rebuilt and performance-built VR38DETT engines. Essential maintenance for any bottom-end rebuild, and a recommended upgrade over OEM for boosted or track-driven GT-Rs. Verify your block's factory grade stamp before ordering. Thrust washers are sold separately. Set covers all four main journals (8 shells total).