[James Montigny]

I'm interested in hearing about block casting failures.
What did you have done and what ultimately led to failure?

Overheating? Bearing walk? Physical component failure?

[radz28]

Isn't about the closest thing to a block issue the half-thrust bearing we get? I mean, I know there's the new oil BS, and earlier oil pump-type stuff for some applications, but with drop-in stuff, like you already have, the block itself is fine, isn't it? I've seen many tuners say up to around 950 for LT4s is about the safe limit (because of the thrust bearing), and it's the same block.

[Joshinator99]

Originally Posted by radz28

Isn't about the closest thing to a block issue the half-thrust bearing we get? I mean, I know there's the new oil BS, and earlier oil pump-type stuff for some applications, but with drop-in stuff, like you already have, the block itself is fine, isn't it? I've seen many tuners say up to around 950 for LT4s is about the safe limit (because of the thrust bearing), and it's the same block.

Agreed. With the thrust bearing addressed I know LME rates their OEM block stuff to 1100 HP with no sleeve and I think it’s 1400 HP with Darton sleeves. The OEM block is pretty damn good right out of the box.

[James Montigny]

Yes, that's what I am seeing. Most failures seem to be related to some other part causing the initial damage.
There are also more stock LT1 and LT4 blocks holding up in 800+ rwhp cars than I expected to find.
I expected to find more main cap failures or integrity cracks under high cylinder pressure.

[L78toLT1]

Originally Posted by Joshinator99

Agreed. With the thrust bearing addressed I know LME rates their OEM block stuff to 1100 HP with no sleeve and I think it’s 1400 HP with Darton sleeves. The OEM block is pretty damn good right out of the box.

Are you still running the OEM thrust bearing, Josh?

[Joshinator99]

Originally Posted by L78toLT1

Are you still running the OEM thrust bearing, Josh?

Yes.

That said, I will say when I did the AT1 A8, Circle D converter and billet flexplate, we carefully checked crank end play to make sure we weren’t shoving the driveline up against the crankshaft (and therefore the thrust bearing). Not sure if that helped, but I’ve seen other guys do a converter and then they magically lose their engine. I have to wonder if that’s related. But I’m probably on borrowed time anyway….

[James Montigny]

Originally Posted by Joshinator99

Yes.

That said, I will say when I did the AT1 A8, Circle D converter and billet flexplate, we carefully checked crank end play to make sure we weren’t shoving the driveline up against the crankshaft (and therefore the thrust bearing). Not sure if that helped, but I’ve seen other guys do a converter and then they magically lose their engine. I have to wonder if that’s related. But I’m probably on borrowed time anyway….

Yeah, I think you're hogging all the stock block luck from the bucket. It feels like it's been years since you built that thing up.

My bottom end was rebuilt when we installed the forged / balanced assembly last year. But since the converter and flexplate are coming off for upgrades anyway, it's probably wise to see what damage I've managed to do in 7k miles.

[GreyGhost702]

When I started my build I was going to use another block so I didn't have to put my car down for as long. Unfortunately the engine I bought had a spun thrust bearing unbeknownst to the owner. Engine came out of a '22 A10 with ~12k/mi, was H/C/I FBO for mods w/stock converter. My only guess, aside from the half-thrust bearing just being a weak design, was the trans tune may have had a role to play in it, or some kind of abuse from the A10. Could have been a one-off from the factory, maybe end play wasn't set right from the factory. Owner stated he never saw metal from oil changes and the shop that did his engine swap didn't alert him to any damage or floating metal when they swapped some of the parts to his new build. I could see possibly not seeing metal from the pan, but there's no way there wasn't glitter in the oil filter or chunks of bearing in the pickup tube. The pickup tube went on his new engine, so if the shop claims everything was clean... I have a heavy machine shop locally that claims they can repair the block and main cap and bring it back to tolerance, but everyone else has told me it's a paperweight or a nice table base. I'm interested in letting the caterpillar shop have a go at it. Would be nice to throw the stock internals back in it and have a spare if I ever set the car back to stock to sell, or at least keep it on the side as a backup.

My engine was pretty good on the teardown. I only found the rod bearings to be a little concerning. I ran the recommend 0w40 oil spec and changed twice a year or every 5k/mi, whichever came first. Still, the rod bearing wear seemed excessive to me, for an engine with only 17k/mi on it. My thrust wasn't in bad shape, but I wasn't happy with it. The driveline side had seperated from the main, all that was really keeping it in place was the tangs and the crank. I suspect at some point, it would have spun as well. It's not enough that it be shitty for being a half thrust, but then the thrust side is barely tacked to the main bearing, 2 tiny little beads keep it together. I went ACL bearings on my build, full 360 thrust. Much beefier compared to OE. Some builders recommend drilling additional oil passages to the thrust, but I honestly didn't feel I needed it. Oil is being slung all over the crank pretty well, and as long as end play is set correctly and I'm not riding the clutch, it should do well in my application. If I were regularly tracking the car or racing competitively, I would probably opt to have the thrust drilled. But then again, I'd be aware that I'd be refreshing the engine every season or two, as needed.

Some shots of the spun thrust carnage from the '22 block and then the bearings from my engine as well. Again, the rod bearing wear bothers me. I've seen worse come out of other engines that were running just fine, though.