Fixed my boost issue.....but spun a bearing this morning

[LeRoyDL]

looks aluminum... Donniekak, you don't think its from main seal housing? (one of the two that come in through the bottom?)

edit phone typos

[donniekak]

looks aluminum... Donniekak, you don't think its from main seal housing? (one of the two that come in through the bottom?)

edit phone typos

Now that I take a second look, it very well could be. I thought I had a rear main housing to look at, but I don't.

[familyMAN]

Sin, I see you started a part out thread. Did you pull rod caps and girdle to confirm you spun a bearing?

[Sin'sVr4]

no, with that much metal, dont know what else it could be.

[familyMAN]

Always good to check. Could be a wrist pin since you didn't sound completely convinced the sound was a knocking rod. Sounds like you will part out no matter what but it would be good to know to advertise and sell parts correctly. Wrist pin would trash your block, a piston and a rod. A spun/smashed bearing keeps your block and pistons useable and maybe all rods.

[Sin'sVr4]

ya, thats why i havent put a price on those yet. i will pull the engine this weekend and tear the block down to look. everything looks good from under neath, but you know how that goes

[J. Fast]

Did a failure analysis on Mike's motor today. The rod bearings were oil starved. They heated up from lack of lubrication and flattened. There was excessive crank walk on the thrust side also. Two mains also got cleaned out in the process.

The bearings were "pounded flat" because of localized heat from a lack of oil cooling, not torque.

There were no signs of detonation. The engine failure was not tune related.

I'll post some pics up when I get time.

[Chris@Rvengeperformance]

Yeah if the center mains were wiped out it causes the rods to starve. The center mains are damaged by crank flex from exceeding mtbt. Typical failure and almost exactly what mine did.



I also had zero signs of detonation.


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[Greg E]

Yeah if the center mains were wiped out it causes the rods to starve. The center mains are damaged by crank flex from exceeding mtbt. Typical failure and almost exactly what mine did.



I also had zero signs of detonation.


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This.

The crank literally gets turned into a jump rope. Mains fail which then starves the rods.

[J. Fast]

Observations...

4 bolt main in a 1G engine bay with a 2nd gen forged crank.
Bi-Metal bearings on a forged crank... <this bearing selection is hrmm>



Accelerated metal fatigue was present on one main (so much the aluminum lining was stripped entirely).




The fatigue stripped aluminum migrated thru the crank journal and clogged the adjacent oil passage for rod bearing#2.



Metal continued to travel and contaminated the adjacent main where you can see it entered the journal and wiped fragments.



Fragments from second damaged main travel to adjacent rod and are imprinted into #4 bearing. (#4 rod bearing on left, #2 rod bearing on right)



Oil passage to #2 rod is completely blocked and oil film thickness was reduced. Bearing heated up due to excessive friction from oil starvation and expanded flat. Clearance was lost and fun was over...



^^This picture illustrates how much a bearing expands when a uniform oil film thickness is not maintained. The front bearing pair which looks new is from rod bearing #3 and the rear is rod bearing #2. #2 bearings expanded roughly 1/8" which pushed the thrust bearings forward and led to crank walk.

Accelerated thrust bearing damage was also observed but I'm not going to get into those details because run-out it was not the failure point.

First big question I have is why were bi-metal aluminum bearings selected for a high horsepower build for one, and utilized on a forged crank, two?

These bearings that are getting flattened are not because of early torque. Diesel engines use the same bearings and produce 1000ftlbs and they don't flatten. The issue is maintaining a uniform oil film at the bearings to keep the assembly floating which in turn keeps the temperature down. If you're flattening bearings the fix is finding a way to maintain the oil film there and keep it cooler. When bearings expand it's usually because there's metal to metal contact not metal/oil film/metal contact.

Here's a fantastic Q/A on engine bearing design, selection, and failure analysis from:

... Federal-Mogul Corporation: Bob Sturk, Chief Applications Engineer, Bearings: North America; and Raymond King, Director of Global Engine Parts. From King Engine Bearings: Dr. Dmitri Kopeliovich, R&D Manager at King’s manufacturing facility in Israel; and Michael James, with King’s export and high performance programs. From MAHLE Clevite Inc.: John Havel, former Director of Aftermarket Engineering (Retired); and Bill McKnight, Team Leader – Training.

A View From The Summit: Expert Engine Bearing Analysis for the Engine Builder