What does '.25mm oversized' mean for these bearings?

This means the bearings are slightly larger in diameter than standard. They are intended for use with a crankshaft that has been machined down by 0.25mm on its main journals. This is a common practice in engine rebuilding to ensure a fresh, perfectly round surface.

What is the construction of these ACL main bearings?

These bearings feature a tri-metal construction. This design provides a good balance of strength to support the crankshaft and conformability to protect the bearing surface and maintain oil pressure.

Are these bearings suitable for a stock engine rebuild?

While these are high-performance bearings, they can be used in a stock rebuild if the crankshaft has been machined to the correct .25mm undersize. They offer improved durability over standard bearings, especially if the engine might see harder use.

ACL Main Bearing Set 5M8353H-.25 - Mazda B6/BP/BP-T 1.6/1.8L

Name: ACL Mazda B6/BP/BP-T 1.6/1.8L .25mm Oversized High Performance Main Bearing Set
Brand: ACL
SKU: acl-acl-mazda-b6-bp-bp-t-1-6-1-8l-25mm-oversized-high-performance-main-bearing-s-t14-18420
Price: 79.86 USD
Availability: InStock

ACL Mazda B6/BP/BP-T 1.6/1.8L .25mm Oversized High Performance Main Bearing Set

$79.86

In Stock

ACL Mazda B6/BP/BP-T 1.6/1.8L .25mm Oversized High Performance Main Bearing Set

Key Features

Fits Kia Rio, Sephia, Mazda 323, MX-3, Miata, Protege, and Mercury Capri.
Designed for Mazda B6, BP, and BP-T 1.6L and 1.8L engines.
Main bearings are .25mm oversized for use with a machined crankshaft.
Tri-metal construction offers strength and conformability.
High performance bearing set suitable for rebuilt or performance engines.

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Will this fit your vehicle?

Product Details

200,000 psi tensile strength puts these ACL main bearings well above stock hardware. If you're rebuilding or refreshing the bottom end of your Mazda B6, BP, or BP-T engine, especially if you're pushing more power, a strong set of main bearings is crucial for keeping everything aligned and running smoothly. These are .25mm oversized, meaning they're designed to be used when the crankshaft journals have been machined down by that amount to true them up or account for wear.

ACL has been making engine bearings for a long time, and these are built to handle the demands of performance applications. They use a tri-metal construction that offers a good balance of strength and conformability, helping to protect your crankshaft while maintaining oil pressure. The .25mm undersize means they're intended for use with a crankshaft that has been ground to this specific dimension, which is common practice in performance engine builds to ensure a fresh, perfectly round surface for the bearings to run on.

When you're putting an engine back together, especially one that's going to see harder use, using a well-built bearing set like this from ACL is a smart move. Make sure your crankshaft has been professionally machined to the correct .25mm undersize before installing these bearings.