If you're diving into the world of high-performance engines, you know the importance of solid bearings. That's where the ACL Race Series Engine Bearings come into play. These aren’t just any bearings; they’re designed specifically for those who push their engines to the limit, whether you're revving a 4, 6, or 8-cylinder beast. Trust me, these bearings are built to handle the heat and the RPMs.

What makes these bearings stand out?

• First off, they have a high-strength overlay plate that’s thinner than what you typically see. This isn’t just for show; it improves fatigue properties, so you can count on them under stress.
• All rod bearings come with hardened steel backs. This means better support for the bearing lining and helps keep everything snug in its housing.
• They’ve increased the crush on these bearings, which means better retention. You want your bearings to stay put, right?
• No flash plating on the back—this is a biggie. It enhances heat transfer and improves grip between the bearing and housing, which is crucial when you're pushing your engine hard.
• These bearings have increased eccentricity too, which compensates for bore distortion at high RPMs. This helps in forming those hydrodynamic oil films that are vital for smooth operation.
• 3/4 grooved main bearings? Yes, please! This design optimizes the load-carrying surface area and ensures oil flows nicely to the conrod bearings.
• With tight wall tolerances, you can maintain consistent clearances, which is essential for performance.
• They’ve even enlarged the ID chamfers on the edges where needed to fit those performance crankshafts with larger fillet radii.

Let’s get into the nitty-gritty specs:

• Size: STD
• Oil Clearance: +0.001" Extra
• Half Type: Upper & Lower
• Material: Tri-metal Hardened Steel Backs
• Min Std Shaft Size: 2.3611in / 59.971 mm
• Max Std Shaft Size: 2.3618in / 59.990 mm
• Min Std Tunnel Size: 2.5591in / 65.000 mm
• Max Std Tunnel Size: 2.5598in / 65.019 mm
• Max Wall at Crown: 0.0930in / 2.478 mm
• Max Overall Length: 0.787in / 20.00 mm

Compatibility: If you’re rolling with a BMW Z4 from 2003 to 2015, these bearings are a perfect match. Specifically, they fit the M20/M50/M52/M54 engines with a 1919CC displacement, 80.0mm bore, and 66.0mm stroke. You’ll get that precise .001in clearance on the standard main bearing set, ensuring everything runs smoothly.

In short, if you’re serious about your engine’s performance, you’ll want these bearings in your corner. They’re built tough, designed for high RPMs, and ready to keep your engine running at its best.