There were a number of problems with the Vega engine, none of which had much to do with the silicon/aluminum process.

First, it had a cast iron head (huh?????) because Chevy couldn't get an aluminum one to stay together soon enough for production (and production was on an "emergency" basis becuase the Wankel rotary didn't work). Differential expansion was a serious problem, exacerbated by the cheap head gasket.

Second, the block design itself was defective -- no coolant between the cylinders, so if it got hot, the bore went serious out of round because the walls grew between the cylinders too much. Instant bore/cylinder abrasion, followed by copious oil burning. Just sitting it traffic was enough, and even a small amount of coolant loss would do the engine in. This was fixed after the first year of production, I think, but re-designing the block to fix the "shrinking bore" problem. Buick (who pioneered aluminum blocks in the early 60s) didn't have this problem due ot the steel sleeves (dry ones) they used. When the steel sleeve was removed, the bores changed shape.

Third, the head gasket problem, compounded by using a cast iron head. Coolant leakage into the cylinder is bad news, as noted above.

Last, even if the engine survived -- and the later ones did, forever -- the body was junk. Ed Cole's reply to people who wanted inexpensive cars (he called them "cheap") -- sloppily designed, lousy materials, poorly built. I suspose he thought he was "teaching them a lesson" by building a travesty of a car and telling people "but you wanted a cheap car!". Deliberate misunderstanding -- I believe he was the guy who took the camber limiter off the Corvair to save $1.50 per car and killed several thousand people, too.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!