[ffindling]

I'm not sure the Vega block should be included in a discussion of the merits
of aluminum blocks. The Vega block was linerless and practically all aluminum
blocks on the market these days have cast iron liners. GM developed the
Vega block conjunction with Reynolds who developed an alloy known as 390
and a heat treatment process to go along with it. The idea being that the
390 alloy could heat treated to give cylinder bores good wear characteristics.
It actually worked quite well and in testing, GM ran the engines for over 150K
miles with good results. But the engine suffered for two reasons, first was
abysmal build quality which plagued the entire industry during those times.
The engine needed to be built to fairly exact tolerances and instead they
were slapped together with a degree of sloppiness never seen before. The
other reason was overheating. Consumers often let their cars overheat,
traditional cast iron engines could tolerate that to a degree but the Vega
engine could not tolerate overheating in the least because overheating destroyed the heat treatment on the cylinder bores and once that was
destroyed the engine would gall itself to death. The Vega debacle pretty
much ended the industry's foray into linerless blocks although a few manufacturers have reintroduced linerless blocks in recent years such as
Mercedes and BMW.

....Fred