ACL Race bearings, BMW N54 / N55 engines, main crankshaft bearings

ACL Race main bearings for BMW N54B30 / N55B30 / S55B30 engines

ACL Race Series bearings for engines where standard bearings are no longer enough.

ACL Race is a well-known bearing range among performance engine builders and racers, combining OEM-style surface characteristics with a structure designed to withstand high loads. These bearings are equally suitable for reliable street use and demanding track or competition applications.

ACL Race bearings are widely used in highly modified BMW, Honda and Nissan engines, as well as countless other high-performance engine builds.

Features

• Excellent value for money, often priced below comparable OEM bearings.
• Priced per complete set, covering all crankshaft main bearing journals for the engine.
• Ensure that the crankshaft bearing journals are in perfect condition during installation. Machine or polish them as required.
• IMPORTANT: Always follow ACL’s recommended bearing clearances during assembly. Excessively tight bearing clearance can cause serious damage, especially in modified engines.

Available sizes

Most ACL Race bearings are available in several size options:

• STD – standard size.
• 0.25 – undersize for crankshafts that have been machined due to wear.
• 0.50 – larger undersize for crankshafts that have required more extensive machining, for example after bearing damage.
• HX – special size providing approximately 0.025 mm additional bearing clearance. Designed for modified engines using a new or standard-dimension crankshaft.

For example, if an engine has a factory bearing clearance of around 0.03 mm and a modified build requires approximately 0.05–0.06 mm, HX bearings can provide the desired additional clearance without unnecessarily machining the crankshaft journals.

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ACL Race Series bearing construction

ACL Race is a bearing range designed specifically for modified engines and applications subjected to high loads.

The bearings use a multi-layer construction that combines the advantages of different bearing materials. The design aims to provide excellent wear resistance, high load capacity and reliable performance under increased cylinder pressures and engine speeds.

The illustration shows the multi-layer construction used in ACL Race bearings.

Comparison of different bearing materials and their durability characteristics.

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For more detailed information about ACL Race Series bearings, see the manufacturer’s guide.

View the ACL Race Series catalogue (PDF)

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BMW 1-series [2007–2013] BMW 2-series [2014–2021] BMW 3-series [2007–2020] BMW 4-series [2014–2020] BMW 5-series [2010–2017] BMW 6-series [2011–2018] BMW 7-series [2013–2015] BMW M-series / M2 [2016–2021] BMW M-series / M3 [2014–2020] BMW M-series / M4 [2014–2020] BMW X3 [2011–2017] BMW X4 [2014–2018] BMW X5 [2014–2018] BMW X6 [2015–2019]