When building a high-performance engine, every component must be selected for durability and power. The engine bearings, particularly the main and rod bearings, are among the most critical. They are the foundation upon which your rotating assembly operates, and choosing the right set can mean the difference between a reliable powerhouse and a catastrophic failure. For racers and engine builders, ACL Race Series bearings have long been the standard for aftermarket performance.
These bearings are engineered to withstand the extreme pressures and high RPMs found in competitive environments. With features like enhanced oil control, increased strength overlays, and specific clearances for different applications, they offer a significant upgrade over stock components. This roundup focuses on eight of the best ACL Race bearing sets designed to deliver the performance and longevity your project demands.
Our Top Picks for ACL Race Bearings
- ACL RACE Bearings for Acura Honda B16A B18A B18B B20B
- ACL Race Bearings for Subaru WRX STi EJ20 EJ25 STD
- ACL Race Series Bearing Set for 1JZ 2JZ Supra IS300
- ACL Race Rod & Main Bearings for Honda D16A1 D16Y5
- ACL Race Series Rod & Main Bearings for Acura/Honda
- Fastenal 5520077 ACL Race Bearing Set
- ACL Race Series Main Bearing Set 4M8125H-STD
- ACL 5M8133H-STD Race Series Thrust Washer Set
ACL RACE Bearings for Acura Honda B16A B18A B18B B20B
This comprehensive set is engineered for Honda B-series engines, a popular platform for both street and track builds. It includes everything needed for a bottom-end rebuild: main bearings, rod bearings, and thrust washers. The standard size ensures a direct replacement for worn OEM components, making it a straightforward upgrade.
The bearings are constructed from ACL’s Race Series material, identified by the “H” suffix, which is designed for high-load and high-RPM applications. This set provides improved durability over factory bearings, helping to ensure the rotating assembly remains stable under the stress of forced induction or aggressive tuning. It is a reliable choice for revitalizing a high-mileage block or building a robust performance engine.
ACL Race Bearings for Subaru WRX STi EJ20 EJ25 STD
Subaru’s EJ20 and EJ25 turbocharged engines are known for their performance potential but can be demanding on internal components. This ACL Race set is specifically designed to meet those demands. It features a high-strength overlay plate that is reduced in thickness to promote better oil control and less friction, which is vital for engine longevity and power output.
Further enhancing its reliability, the set includes hardened steel backing on all connecting rod bearings and is engineered with increased crush for better retention in the rod housing. These features work together to provide a more stable and durable foundation for the crankshaft, making this bearing set an excellent selection for anyone upgrading or rebuilding a high-performance Subaru engine.
ACL Race Series Bearing Set for 1JZ 2JZ Supra IS300
For the legendary Toyota 1JZ and 2JZ inline-six engines, this ACL Race bearing kit offers a key performance enhancement. The set includes both rod and main bearings in a standard size but with a crucial difference: an extra .001″ of oil clearance. This additional clearance is particularly beneficial for high-horsepower and high-RPM applications where increased oil flow is necessary for cooling and lubrication.
Whether you are building a boosted 2JZ-GTE for a Supra or refreshing a 2JZ-GE in an IS300 or SC300, this bearing set helps support the engine’s renowned strength. The optimized oil clearance can contribute to lower operating temperatures and reduced risk of oil starvation, providing an added layer of protection for your investment.
ACL Race Rod & Main Bearings for Honda D16A1 D16Y5
Honda’s D-series engines are a cornerstone of the import tuning scene, prized for their affordability and potential. This ACL Race Series set brings professional-level bearing technology to these popular four-cylinder engines. The standard size bearings provide a precise fit for a straightforward installation during a rebuild.
Constructed from the same high-quality Race Series material as ACL’s other performance offerings, these bearings offer superior load capacity and fatigue resistance compared to stock parts. This upgrade is a smart move for anyone looking to build a reliable, high-revving D-series engine, whether for daily driving or competitive use.
ACL Race Series Rod & Main Bearings for Acura/Honda
This combo set provides a complete bearing solution for a range of Acura and Honda vehicles using B16, B18, and B20 engine blocks. By bundling the rod and main bearings together, it simplifies the parts sourcing process for your engine build or overhaul. The bearings are designed to the exacting standards of the ACL Race Series.
The use of advanced bearing materials ensures consistent performance under the thermal and mechanical stresses common in modified engines. This set is an ideal foundation for a performance build, offering the reliability needed to handle increased power from turbocharging, supercharging, or high-compression naturally aspirated setups.
Fastenal 5520077 ACL Race Bearing Set
This bearing set, identified by its Fastenal part number, is another entry in the ACL Race lineup. While the specific application may vary, it shares the core engineering principles that define the Race Series. These bearings are built for situations where factory components are not sufficient.
The set is manufactured to provide increased strength and durability for high-output engines. For builders who have identified this specific part number for their project, it represents a trusted component from a leading brand in performance engine bearings.
ACL Race Series Main Bearing Set 4M8125H-STD
This is a main bearing set from ACL’s Race Series, designated by the part number 4M8125H-STD. Main bearings are responsible for supporting the crankshaft itself, making them fundamental to engine stability and smooth operation. This set is designed to handle the increased loads from high horsepower and RPM.
The “H” suffix indicates the specific Race Series material composition, which offers enhanced performance characteristics. For engine builders who need to replace only the main bearings or are sourcing components individually, this set provides the quality and reliability expected from the ACL brand.
ACL 5M8133H-STD Race Series Thrust Washer Set
Thrust washers are a critical, though often overlooked, component in an engine rebuild. They control the crankshaft’s fore-and-aft movement, and failure can lead to significant engine damage. This ACL Race Series thrust washer set is manufactured to provide superior wear resistance and dimensional stability.
When paired with a set of ACL main bearings, these thrust washers ensure that the entire rotating assembly is secured with components designed for performance. Using race-spec thrust washers is a prudent step in any serious engine build, helping to prevent crankshaft walk and ensuring long-term reliability.
Buying Guide: How to Choose the Best ACL Race Bearings for Performance and Longevity
When I am building or rebuilding a performance engine, the choice of bearings is one of the most critical decisions I make. It is not just about picking the most expensive option; it is about matching the bearing to the specific demands of my engine and how I plan to use it. ACL Race Bearings are a go-to for many builders, but even within their lineup, there are key differences that can make or break a build. Here is what I look for to ensure I get the best ACL Race Bearings for performance and longevity.
First, I always consider the bearing material. ACL offers two main types in their performance line: the standard Aluglide (aluminum-tin-silicon) and the more advanced Tri-Metal (copper-lead-indium). For most of my high-horsepower, high-RPM race engines, I lean towards the tri-metal bearings. They have excellent embedability, meaning they can absorb small particles without causing catastrophic damage, and their fatigue strength is superior under extreme loads. The Aluglide bearings are fantastic for street performance or moderate racing applications because they are incredibly durable and have great corrosion resistance.
Clearance is the next big factor, and it is not something to guess on. I never just slap in standard-sized bearings and hope for the best. Proper oil clearance is the lifeblood of the bearing. Too tight, and you risk oil starvation and seizure; too loose, and you lose oil pressure, leading to wear and potential failure. I always have my machinist measure the crank journals and bearing bores precisely. ACL offers bearings in standard, undersize, and even H-Series (high-performance) clearances. For a race engine, I often opt for the slightly larger clearances found in the H-Series to account for thermal expansion and ensure a robust oil film at high temperatures.
Finally, I think about the specific application. Am I building a turbocharged four-cylinder that sees sustained high boost, or a high-revving naturally aspirated V8? The loads are different. For turbo applications where shock loads from boost are a factor, the shock resistance of a tri-metal bearing is a huge benefit. I also make sure to check ACL’s catalog for engine-specific main and rod bearing sets, as they often have tailored solutions for popular performance engines. Investing the time to understand my engine’s specific needs and matching them with the right ACL bearing material and clearance is what guarantees both performance and longevity.
Frequently Asked Questions
What is the main difference between ACL standard and race series bearings?
The main difference comes down to material and intended use. The standard series bearings are typically made from an aluminum alloy and are designed for reliable service in stock or mildly tuned street engines. The race series, however, uses more advanced materials like their tri-metal construction. This is designed specifically to handle the extreme pressures, high RPMs, and shock loads encountered in competitive racing. The race bearings are built for ultimate strength and fatigue resistance, which is why they are the preferred choice for anyone seeking the best ACL Race Bearings for performance and longevity in a high-stress environment.
Do I need to get my engine block and crank machined if I use ACL race bearings?
In almost all cases, yes, you absolutely should. Installing new bearings, especially performance ones, into a used engine without proper machining is a recipe for failure. The old bearings wear, and that wear is mirrored on your crankshaft journals and in the engine block’s bearing saddles. Simply dropping in new bearings will not correct for any out-of-round conditions or microscopic imperfections. I always have a machine shop professionally measure and, if necessary, machine the crankshaft and check the block alignment. This ensures the new bearings have a perfect, clean surface to work with and that oil clearances are precisely within specification.
How important is break-in for new ACL race bearings?
It is critically important. The break-in process seats the bearings against the crankshaft and establishes a protective wear pattern. For a fresh engine with new ACL race bearings, I follow a very specific procedure. This usually involves running the engine at varying RPMs (not just idling) for the first 20-30 minutes to properly load and lubricate the bearings. Using a high-quality break-in oil without friction modifiers is also essential. This initial run-in period creates a stable oil film and conditions the bearing surfaces for long-term durability. Skipping or botching break-in can lead to premature wear or even spinning a bearing.
Can I use ACL race bearings in a daily-driven street car?
You certainly can, and many people do, especially if the engine is significantly modified. The race bearings are overbuilt for street use, which can be a good thing for peace of mind. However, for a purely stock engine that is just a daily driver, the standard ACL bearings are more than sufficient and are a cost-effective upgrade over OEM. The race bearings really shine when you have increased horsepower, higher cylinder pressures from forced induction, or plan to regularly take the engine to its redline. For a street car that sees occasional track days or has a big turbo, the extra margin of safety from the race series is a wise investment.
What causes an ACL bearing to fail prematurely?
From my experience, premature bearing failure almost always traces back to one of a few common issues. The top culprit is improper oiling, which includes using the wrong oil viscosity, low oil level, or oil that is contaminated with fuel or coolant. Second is incorrect installation, such as wrong clearances, a dirty engine assembly, or improper torquing of the bearing caps. Third is detonation or pre-ignition in the engine, which creates massive shock loads that can literally pound the bearing material out. Finally, a damaged or worn crankshaft will quickly destroy even the best new bearing. Proper build techniques, maintenance, and tuning are key to preventing these failures.