What does '0.25mm oversized' mean for these bearings?

This means the inner diameter of the bearing is slightly larger than a standard bearing by 0.25mm. This size is used when the engine's crankshaft journals have been machined down (ground) to remove imperfections or wear, and need a larger bearing to restore the correct oil clearance.

Are these bearings suitable for a stock Lancer engine?

These are high-performance bearings designed for demanding applications. While they can be used in a stock engine if the crankshaft has been machined to accept them, they are particularly well-suited for modified or performance-tuned 4B11T engines.

Do I need to replace the main bearing bolts as well?

It is highly recommended to replace main bearing bolts when replacing the bearings, especially in performance applications. Always consult the manufacturer's service manual for specific recommendations regarding hardware replacement during engine assembly.

ACL 08+ Mitsubishi 4B11T Evo X 0.25mm Oversized High Performance Main Bearing Set

Specifications

Brand: ACL
Part #: 5M1237H-.25
UPC: 9315726276341

ACL 08+ Mitsubishi 4B11T Evo X 0.25mm Oversized High Performance Main Bearing Set

Name: ACL 08+ Mitsubishi 4B11T Evo X 0.25mm Oversized High Performance Main Bearing Set
Brand: ACL
SKU: acl-acl-08-mitsubishi-4b11t-evo-x-0-25mm-oversized-high-performance-main-bearing-t14-13162
Price: 101.35 USD
Availability: BackOrder

$101.35

On Backorder — Expected to ship by May 9, 2026

Order now to reserve yours — we'll ship as soon as stock arrives. Full refund if we're unable to fulfill.

Fits 2008, 2010-2015 Mitsubishi Lancer. ACL 0.25mm oversized main bearing set for the 4B11T engine. Built for high-performance applications.

Key Features

Fits 2008, 2010-2015 Mitsubishi Lancer.
ACL main bearing set for the 4B11T engine.
0.25mm oversized for use with machined crankshafts.
Designed for high-performance and demanding applications.
Manufactured to tight tolerances for proper oil clearance.

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Fits this vehicle

Mitsubishi Lancer 2008, 2010-2015

Product Details

When you're rebuilding or upgrading the 4B11T engine in your 2008, 2010-2015 Mitsubishi Lancer, the main bearings are critical. These ACL high-performance main bearings are manufactured to tight tolerances, measuring 0.25mm oversized to ensure a precise fit on crankshafts that have been machined to match. This specific sizing is important for maintaining proper oil clearance, which is key to engine longevity and performance, especially when you're pushing the engine harder than stock.

ACL has a solid reputation for making well-built engine components, and this main bearing set is no exception. They are designed to handle the increased stresses that come with performance tuning or heavy-duty use. The material and construction are chosen to provide reliable lubrication and support for the crankshaft under demanding conditions. If your crankshaft has been reconditioned or is slightly out of spec, these 0.25mm oversized bearings are the correct choice to bring everything back into alignment.

When installing these bearings, always refer to the manufacturer's service manual for the correct torque specifications and assembly procedures. Ensuring proper installation is just as important as using a quality part like this ACL set for the health of your 4B11T engine.