ACL Race Series Main Bearings .25 Over (7 Bolt DSM 1993-1996) ACL 5M1186H-.25PART# ACL 5M1186H-.25
ACL Race Series Performance Engine Bearings
The unique combination of design, metallurgy and engineering come together to deliver what drivers expect from high performance Trimetal engine bearings.
- Designed to withstand higher RPM conditions.
- High strength overlay plate with reduced thickness for improved fatigue properties.
- Hardened steel backs on all rod bearings to improve the support of the bearing lining and assist with bearing retention in the housing.
- Increased crush for improved bearing retention.
- Elimination of flash plating on the back of the bearings to improve heat transfer through the bearing sand to maximize the grip between the bearings and its housing.
- Increased eccentricity to compensate for bore distortion at high rpm and to assist in the formation of hydrodynamic oil films.
- 3/4 grooved Main Bearings to optimize bearing load carrying surface area and oil flow to the conrod bearings.
- Tight consistent wall tolerances to help you maintain consistent clearances.
- Enlarged ID chamfers on bearing edges where required to accommodate large fillet radius on performance crankshafts.
What is the maximum power rating of ACL Race Series bearings?
- 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!