SEMA 2021: King Bearings Talks Bi-Metal And Tri-Metal Differences

Over the past few years, we’ve talked a lot about King Engine Bearings’ latest and greatest XP-series of pMaxBlack and pMaxKote engine bearings. However, when we spoke to King’s Ron Sledge at SEMA, he mentioned that with all the talk about the XP series, the company’s HP-series bearings are being overlooked for their proper application due to some confusion on the differences between the two bearing types.

“The primary differences are that the HP is a bi-metal bearing and the XP is a tri-metal design,” Sledge explains. He also explains that since the XP bearings are black (whether coated or not) and the HPs are bare silver, they are referred to as “black” bearings and “white” bearings. “We get a lot of calls about which bearing to use, and when to use a black bearing versus a white bearing.”

Cosmetics aside, the two bearing lines are designed for two different applications. “The bi-metal bearing has good embeddability and conformability. Over the long haul, it will absorb some of the debris that gets into the motor and bearings, making it ideal for street use where you aren’t taking the engine apart and inspecting it often, if at all,” says Sledge.

On the left is the bi-metal HP-series bearings, which are designed for street applications. On the right are the XP-series pMaxBlack bearings designed for race engines.

“The tri-metal bearing doesn’t absorb that well, since it’s an all-out race bearing. The pMaxBlack isn’t a good street bearing, since it doesn’t absorb debris much. It’s more aimed at engines that are frequently torn down. So, if you’re building a street/strip car, I would suggest a bi-metal bearing, and if you are building an all-out race engine where you are going to be tearing it down quite often, the tri-metal bearing,” Sledge adds.

Moving on to the available pMaxKote bearing coating, Sledge explains that it’s only available on the XP-series bearings, and is designed to increase lubricity in the case of inadequate oil lubrication. “If everything is working well — the oiling system is good, the oil is good, and the clearances are good — the coating doesn’t really help you. But, if you have something happen where the oiling system hiccups or the clearances aren’t exactly right, the coating is a layer that adds non-metallic lubricity to the bearing.”

To learn more about King’s line of engine bearings, check out its website, or one of the previous articles we’ve written.

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About the author

Greg Acosta

Greg has spent seventeen years and counting in automotive publishing, with most of his work having a very technical focus. Always interested in how things work, he enjoys sharing his passion for automotive technology with the reader.
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