If you’re diving into the world of high-performance engines, you’ll want to pay attention to the ACL Race Series Engine Bearings. These aren’t just any bearings; they’re crafted with a unique blend of design, metallurgy, and engineering that truly meets the demands of serious drivers. Whether you’re pushing a 4, 6, or 8-cylinder setup, these bearings are built to handle the high RPM conditions that come with spirited driving.

What sets these bearings apart? For starters, the high-strength overlay plate is thinner, which means it’s got improved fatigue properties. This is crucial when you’re really pushing your engine to the limit. The hardened steel backs on all rod bearings provide solid support for the bearing lining, ensuring they stay put even under pressure. Plus, there’s an increased crush that helps with bearing retention, so you won’t have to worry about them shifting around when the engine gets revved up.

One of the standout features is the elimination of flash plating on the back of the bearings. This little change significantly enhances heat transfer, which is essential for keeping things cool when the engine’s running hot. And let’s not forget about the increased eccentricity designed to tackle bore distortion at high RPMs, which helps in forming those all-important hydrodynamic oil films. Trust me, that’s a game changer.

With 3/4 grooved main bearings, you get optimized load-carrying surface area and improved oil flow to the conrod bearings. Consistent wall tolerances mean you can maintain reliable clearances, which is vital for performance. Plus, the enlarged ID chamfers on the bearing edges make sure they fit smoothly with performance crankshafts, accommodating those larger fillet radii.

Now, let’s get into the nitty-gritty specs. You can choose from sizes like STD, .025, .25, and .50, making it easy to find the right fit for your setup. The oil clearance is standard, and these bearings come in identical halves, which simplifies installation. Made from tri-metal hardened steel backs, they’re tough enough to handle whatever you throw at them.

• Min Std Shaft Size: 1.967in / 49.961 mm
• Max Std Shaft Size: 1.9675in / 49.974 mm
• Min Std Tunnel Size: 2.0866in / 53 mm
• Max Std Tunnel Size: 2.087in / 53.011 mm
• Max Wall at Crown: 0.0592in / 1.503 mm
• Max Overall Length: 0.6732in / 17.1 mm

So, if you’re looking to upgrade your Nissan I6 RB25 or RB30 with a .25 oversize high-performance main bearing set, the ACL Race Series is definitely worth considering. These bearings are designed for those who take their engines seriously and want to ensure they’re running at peak performance.