CamaroZ28.Com Message Board - What are the limit's of the LT1 block?

I re-read that other thread and it reminded of something that I meant to point out a couple of times. I am not sure the concept of a block "breaking from sheer power" really makes a lot of sense.

A couple of things happen when the hp is bumped up. Cylinder pressure increases. With the relatively thin cylinders in an OEM casting, the bores distort and the ring seal degrades. This causes power loss, but not usually outright breakge. At some point, cylinders will split. This is more likely on block with an overbore or with core shift. But it's rare, though I suppose it's as good an example as any of a block breaking from "sheer power".

Increased power usually means increased revs. It also means more twisiting and bending of the crank. This tends to distort the main caps leading to bearing wear, possible crank damage and possible catastrophic failure. This is where four bolt caps and better fasteners help. At some point, the block design plays into this because the main caps aren't "crossbolted" like they are in many Al blocks (a la LS1). The thing is, the point at which this occurs is also a function of the components used in the rotating assembly as well as how much hp and the rpm it's run at. A stronger crank will have less bend and twist an place less stress on the caps. A lighter rotating assy will put less stress on the caps due to lower inertial loads. So it makes it very hard to define a certain hp "maximum".

It's clear the SBC main cap design could be improved. I mentioned the LS1, with a deep skirt allowing "cross-bolted" mains. Another example is a drag race aluminum Hemi. Ever look at one? I was helping my firend put his together on Sunday. Beefy billet steel caps held in place by two 1/2" studs oriented vertically and two 1/2" bolts on each side instred through ribs on the block. Strong as hell, but it just can't be done with a Gen I or II SBC. So in that regard, the typical Al block is stronger than a SBC. The cylinders are iron sleeves, so I doubt there is any greater tendency to split than an OEM SBC. An aftermarket SBC has thicker cylinder walls, and is probably more resistant to cylinders splitting than an LS1 though.

Anyway, the question really isn't answerable other than to cite examples. Mine showed some evidence of cap movement at just 733rwhp, and I have a low rev setup. But is that a hp limit for the block? Hard to say.

Rich Krause