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By Jeff Smith February 14, 2019It can be a very tortuous existence for engine bearings. Think about it. Bearings are there to be abused and many engine builders treat them as a consumable. Most of the attention bearings receive is heaped upon design, clearances, and oil feed theory. But once the engine is broken-in and running, attention shifts to other concerns.This story looks at how bearings, coatings, and the oil you choose can have a dramatic effect on bearing life. As you might expect, this means spending a little more money up front, but the results may make that an easy decision.The engineers at King Bearings — headed by Dr. Dmitri Kopeliovich, a leading expert in design, technology and materials for engine bearings — have recently developed a new performance rod and main bearing called the pMaxBlack. This is a bearing with major changes to the tri-metal alloy, in a quest to create a material that is still soft enough to handle a high-output engine, while simultaneously offering increased fatigue resistance and load carrying capacity. The inside story on how King developed this bearing is steeped in alloy-metal technology, so let’s just say they figured out a way to make a bearing stronger to withstand the abuse from increased power levels while still making it soft enough to properly do its job.Bearing TheoryRace or performance oriented tri-metal bearings are built intentionally soft because, if a rod journal deflects or a crankshaft bends under high load, the journal may contact the bearing. If the bearing is soft enough, it merely wears slightly. Unfortunately, cold startups tend to take their toll on engine bearings, since the crank rotates for several revolutions before the film of oil builds up between the bearing and the journal. This is why you often see race teams pressure lube the engine each time before cold startup.King ‘s aluminum-alloy bearing material (HP prefix) is used in very high-load applications. According to Ron Sledge of King Bearings, “The duration of time of the loading is what separates which bearing to use, HP vs. XP or XPC. The HP will handle very high loading for a shorter period of time (like drag racing) whereas the XP or XPC will handle very high loading for longer time periods, like circle-track and off-road racing.”“The advantage of the HP bearing is that it will tolerate handling debris and crankshaft deflection better than the XP or XPC because of the 0.012-inch thickness of the aluminum layer.” The babbit overlay on the XP bearing is only 0.0005-inch thick. This thinner layer does not tolerate debris and crankshaft deflection as well.Keeping Up With Technology Today’s 21st-century street engines are now making more horsepower than pure competition engines from as little as two decades ago. Builders naturally expect the bearings to keep up with these enhanced power plateaus. This is why King Bearings developed the pMax Black bearings.Taking this idea a step further, King developed a coating for this bearing called pMaxKote. This becomes the ultimate-performance King bearing, employing what the company calls a nano-composite polymer coating. According to Sledge, the term nano-composite just means it is made up of nanosized materials in a polymer base. The coating is added on top of the pMaxBlack overlay and does not increase the thickness of the overall bearing wall.To maintain the same dimensions, King compensates with the thickness of the intermediate copper layer to allow for the 0.0002-inch thickness of the pMaxBlack coating. This allows for maintaining the same oil clearances as uncoated counterparts. The coating protects the bearing from mild abuse and is designed to be extremely wear resistant – even when slight contact is made with the crankshaft. Put To The TestAll of this sounds really good, but the question becomes, how would this coating work in the real world of internal combustion engines? King thought that an independent test would be a good idea, so they collaborated with Lake Speed, Jr. at Driven Racing Oils, and the team at Shaver Specialties, where they set up an abusive test schedule. The plan took shape by placing a relatively mild 440 hp, 383ci small-block Chevy on the dyno. They used a purposely excessive cylinder test regime that would heap serious load on the connecting rod and main bearings and then evaluate the results.This required a baseline or control combination, with a couple sets of King XP, Tri-metal bearings, and Driven supplied a mineral-based, 5W-20 as the baseline lubricant. To make this a true lubricant comparison, the engine oil additive packages had to be exactly the same. Because there were no off-the-shelf mineral-based and synthetics with the same exact additive package, Speed supplied both custom-blended oils for the test.