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What’s Happening At ACL Bearings?


When ordering parts, engine builders at times may have some questions regarding a component. The following are common technical questions regarding ACL performance engine bearings.

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Frequently Asked Questions 
Q  What is the maximum power rating of your Race Series bearings?
A   The power rating of the engine can be tweaked in many ways that have correspondingly different effects on the load and stress borne by the bearings.
All the methods below affect bearing loading:
• Increasing red line engine speed,
• Increasing turbo boost / cylinder pressure,
• Changed timing & cam profiles,
• Using low viscosity oils and/or high engine temperatures,
• Changing crankshaft / connecting rod / piston design,
• Modifying cylinder dimensions (boring out, stroking, decking cylinder head,
As a result it is only realistic to reduce the question to ‘maximum specific bearing load.’  This is the maximum load experienced by the bearing spread over its projected area.
For this the engine builder will need to know peak cylinder pressures and balance these forces with the inertial load (acceleration of piston and conrod masses).
Generally speaking ACL Race bearing materials and design allow a great deal of flexibility for upgrading engine performance having an excellent balance of strength and forgiveness.
The trade-off is: high load = shorter life. ACL Race bearings work well in street machines, that are rarely used at max power, but are expected to have a normal engine life, as well as in ‘Top Fuel’ Dragster engines where bearing loads are several hundred MPa but life is measured in seconds!Q  Some of the ACL Race Series bearings contain an X suffix.  What does this mean?
A   The ACL Race Series Bearings that contain an X suffix have an extra +0.001″ oil clearance over a STD sized bearing.  These bearings are only available in the STD size.

Q  Some of the ACL Race Series bearings contain a D suffix.  What does this mean?
A   The ACL Race Series Bearings that contain an D suffix contain a dowel hole locator in the lower half. This is designed for engines that use dowel pins, but can also be used in engines without dowel pins.

Source: ACL
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