Main Bearings?

Solarsurge

Solarsurge

Greenie N00B Member
Greenie Member
Hey guys. I'm building my engine and I realized the gold standard Clevite H Series Main Bearings are no longer made. I see the King XP tri-metal bearings, but it looks like the thrust bearing is welded and I have never been a fan of welded bearings. Also, the melting point seems pretty low. Should I just go Clevite AL series? What are your opinions out there?
 
Oem main and rod bearings on my built motor. Almost 74k on it now
 
The OEM bearings literally looked brand new on the 190k motor when I tore it down, so they are undoubtedly great bearings. They are aluminum, similar to the Clevite AL series, which is generally MUCH more forgiving to oil starvation and incredibly long lasting. That's why OEM use them. However, AL bearings are only "recommended" for power levels up to 50% above stock. That may be marketing language to steer more people into the H Series bearings, but it's not really worth the risk for me to find out.

I'll be more than double stock power (500+ WHP), high revving for prolonged periods of time, so I think that may be asking a bit much of AL bearings. They don't have the load bearing or fatigue resistance properties and if ANYTHING gets between the bearing and the crankshaft it can be instantly catastrophic because they don't have the same embeddability. That's why the gold standard has been H series on our platform and nearly everyone putting down serious power has them.

With that said, TONS of people swear by King bearings because they're similar to H Series. However, King bearings for some cars have single piece thrust bearings while ours appear to be welded from the pictures I've seen. Welded thrust bearings come with a whole other set of possible defects including weak welds, possible weld spatter, additional clearance issues, etc. It all comes down to quality control. That's why I was trying to see if anyone has any experience with them and could chime in.
 
Fair enough. Just sharing my experience with oem which has taken the abuse I've put it thru with 30+psi on a 5862 almost it's entire life haha
 
I am building one and went with H series Rod bearings but ran into the same wall you did when it came to the mains. I ended up going with OEM for the mains. Following In @Sho’s footsteps and going with OEM Head studs with a 550-600 HP goal.


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Just a heads up, @Littleloogy, my head lifted on the stock head bolts right at 561 back in May. Cyl 4 bolts came out with no effort
 
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I talked with my tuner and with zero hesitation he just said “King bearings.” So, I think I am going to go that route and take the gamble. I’m going with L19 head studs.


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Hmmmm those are tri-metal and are not supposed to last as long for DD life as they are softer to allow more expansion on crazy boost. Wasn't sure if that would be the right choice for me or not. How do you like them?
 
JohnnyTightlips said:
Hmmmm those are tri-metal and are not supposed to last as long for DD life as they are softer to allow more expansion on crazy boost. Wasn't sure if that would be the right choice for me or not. How do you like them?
Click to expand...

I don’t daily it, but they have survived 1500 miles so far and 2 race events.


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JohnnyTightlips said:
Hmmmm those are tri-metal and are not supposed to last as long for DD life as they are softer to allow more expansion on crazy boost. Wasn't sure if that would be the right choice for me or not. How do you like them?
Click to expand...

I do wonder what a realistic life span for a tri-metal bearing would be. 20-30k miles maybe? 50k miles? It probably greatly differs between power levels/driving styles but it would be interesting to know how exactly it compares with an AL/OEM bearing.

With proper maintenance I guess an OEM bearing would basically live as long as the engine so it's probably difficult to judge.
 
alexwlwsn said:
I do wonder what a realistic life span for a tri-metal bearing would be. 20-30k miles maybe? 50k miles? It probably greatly differs between power levels/driving styles but it would be interesting to know how exactly it compares with an AL/OEM bearing.

With proper maintenance I guess an OEM bearing would basically live as long as the engine so it's probably difficult to judge.
Click to expand...
Yeah, I am wondering the same thing and this article goes into good detail but they talk about 1500+ hp engines lol. https://www.hotrod.com/articles/select-install-high-performance-engine-bearings/
 
JohnnyTightlips said:
Yeah, I am wondering the same thing and this article goes into good detail but they talk about 1500+ hp engines lol. https://www.hotrod.com/articles/select-install-high-performance-engine-bearings/
Click to expand...

Simply put, aluminum bearings don’t have anywhere near the load bearing capability that tri-metal bearings have. Aluminum is really only recommended for 100HP per liter typically. The Mazda bearings exceed that already, but they are well engineered and red line is 6700. Once you start raising the red line or modding past a certain power level, aluminum bearings can’t support the load. Also there is less margin of error if you lose oil pressure with tri-metal. Aluminum will just fuck your engine if it loses oil. Tri metal will melt and self lubricate for a short time, likely saving the engine in the process.


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