Rod bearing failures are always a treat to get to the bottom of because the failure mode is so rapid and destructive, rarely is there any good evidence left behind to help determine what the problem was or the root cause.  Some of the failure modes that I have seen analyzing warranty engines at work are due to the following.

1.  Contaminated / Dirty / Old / Overheated Oil.  Oil with coolant, fuel, dirt, etc can take out rod bearings quite quickly.  Navistar, Ford (6.OH-No!), and CAT engines from the 2000's and 20-teens that used EGR extensively to meet emissions are particularly prone to this.  EGR cooler develops an internal coolant leak, and all the sudden your engine is trying to lubricate with the green stuff.  I have also seen a bunch of rod bearing failures in air cooled engines due to oil overheating.  When I was at a small engine manufacturer, the life span of the rod bearing was measured in minutes once the oil hit 350 deg. F.

2.  Machining Quality.  Everything from surface finish, journal roundness, corner radius all can affect the lifespan of the rod bearing, and it doesn't take much of a deviation or miss to shorten the life span from 100,000's of miles to 100's of miles.

3.  Engine (casting) Contamination - See recent Toyota Tundra recall

4.  Crankshaft design / flex.  If the crank flexes more than intended or designed, bearing failure can result.  Typically this is more of a main bearing related problem, but it can lead to rod bearing damage as well.  PACCAR 13L engines are known to experience more crank flex than intended and this will lead to failed bearings.

5.  Rod Bolt Quality.  About 3 years ago, we started seeing a dramatic rise in rod bearing failures on Navistar I-Series reman engines.  Turned out, the rod bolt manufacturer (Navistar chosen and vetted supplier) had changed their process and the bolts were softer and did not have the designed tensile strength.  Bolts would stretch and lose clamp load on the cap, and the bearing would spin.  We discovered the problem by doing an extensive statistical study on our DC tool data (torque and angle) from assembly.  The failure rate was only 3 to 5% of engines, so it was difficult to catch, but there was a statistical change in the data.  The bolts were close to being correct (a measured sample would often meet the engineering print and specs), and they would even torque, yield, and stretch properly during assembly, but would fail within 10,000 miles.  We went down a number of rabbit holes before we figured out the root cause on this one.  Navistar ended up recalling all the rod bolts at their dealers and assembly facilities.

6.  Bearing Material or Quality.  Doesn't take much of a change at the supplier to cause problems in the engine.

Quote from: Stangman on May 01, 2025, 10:35:50 PM

Sounds mean. I’m glad you had a good day. And it’s been a while since you have been out right. You must be pretty close to that track right.

Yes, it's been 5 1/2 years. Way too long. The track is just 1:45 from me, compared to 9 hours, so a HUGE savings in fuel.

For engines like this, you're basically paying for the name. Gucci gloved Cobra drivers want everything to be Shelby. Not putting down Cobra owners, just the snobby type that want everything associated with Shelby. What seems a bit odd to me about the BAT auction is that you can buy basically the exact same engine from Shelby for $27k.
https://classiccobra.com/Shelby_482CID_575HP

Or the 511" for $29k. No horsepower rating on that one for some reason.
https://classiccobra.com/Shelby_511CID

There are a couple of fairly minor differences, which would account for part of the price difference, but why not go straight to the source? I don't think you have any recourse for issues buying an engine on BAT.