[blykins]

That's fine Dave, it's an accepted fact by engine builders that doesn't need to be argued here.

Under higher horsepower conditions, you will lose power with an aluminum block due to cylinder distortion, loss of ring seal, and a decrease of compression. This isn't an operating temperature issue but just a strength issue. I have torn down all-aluminum FE builds where the block was honed with torque plates, but the sleeves still had "shadows" from where the cylinders distorted. I suppose you could "hot hone" the blocks, but there again......why put the effort into it?

To be fair, yes, you can "design in" more compression ratio, but you still have to deal with the squirming around of the blocks. Bearing clearances are something that the engine builder has to set ahead of time, along with running the valves to make sure everything is kosher when it's hot.

I looked at my dyno sheets. I don't have any *exact* combinations where the only difference is the block material. Maybe Barry might have something like that. I think I've talked to Barry about this before (engine builders do talk to each other, BTW) and he said with his career at Federal Mogul, he rubbed elbows with a lot of the race teams....the general consensus was that iron blocks made more power.

Maybe he'll chime in....