In1972, Chevy came out with the Vega, and had a radically-new aluminum-block engine. Everyone said that you couldn't make an engine out of aluminum - it would warp and break down faster than an iron block. And, you know, they were right! The aluminum-block Vega was a disaster, and Chevy had to go back to iron blocks.
Fast forward to 2009, and 85% of the engine blocks made in the US are aluminum-block engines. It took 37 years, but they finally got the bugs out of the process.
A little history correction. The Vega debuted in 1971 and it featured an aluminum silicone engine block. It was not anywhere near the first aluminum blocked engine, that dates back to the 20's. GM actually perfected the aluminum engine back in '62 when they introduced the Buick Special/Skylark, Pontiac Jetfire/Tempest and Oldsmobile F-85/Cutlass (one of my all time personal favorites) with the 215 cu inch aluminum V8. Light, strong and powerful for it's time. The engine was so successful that when GM retired it, they sold the rights to it to British Leyland in 1965, it continued to power their Land Rover SUVs and sedans well into the 1990's. GM got rid of it because it was too small for the horsepower wars and it was expensive to produce.
On a side note, I used to own a 1962 Dodge Lancer with an aluminum I6 in it. So GM was not the only one doing aluminum engines. It was wonderful and light handling, however the head gasket failed on me and I discovered the reason why when I pulled the head (in those days I did a lot of wrenching, these days I pay people) The aluminum had failed around the steel cylinder sleeve due to electrolysis, a common problem in the 60's. People were just used to pouring plain water in the radiator in those days and this practice is death for an aluminum engine. It causes the aluminum closest to the spark plugs to dissolve and redeposit elsewhere in the engine closest to the ground strap. Today's antifreeze solves this problem. In my case, it had failed, somebody pulled the head, put something like JB weld epoxy in the void instead of a proper weld and re-machine and put it back together with a for sale sign on it. Buyer be very aware in the old car business! For the reason of electrolysis problem, the warranty issues made GM, Chrysler and others seriously reconsider aluminum engines until buyers became more technically savvy.
Back to the Vega, a car I also owned and loved. What was different about the Vega's engine was not that it was made of aluminum, but that it was made of an aluminum silicone alloy. The silicone was supposed to give sufficient wear protection and so the expensive process of sleeving an aluminum bore with a steel jacket was removed and the engine was a bit lighter. All aluminum blocked engines prior and since have always had to be cast, bored out, a precisely machined steel sleeve pressed in and then re-machined. GM thought they could cut out this process by changing the aluminum alloy and therefore make aluminum engines almost as cheaply as cast iron engines.
Why did they think this would work? Because that's how race car engines were made. They had been racing aluminum silicone engines for a long time without failure. They thought that if it was good enough to go hundreds of laps at 10,000 RPM, surely it would be good enough to go to the grocery store. Turns out, everyday driving in the hands of amateur drivers is tougher on an engine than racing. The typical Vega engine lasted between 65,000 to 75,000 miles before it was shot. Mine started to go at about 55,000 and I sold it before I had to deal with it.
They continued to make Vegas with aluminum engines, but around I think 1974 or '75 they started putting the steel sleeves in and solved the problem. The engines lived beyond the Vega and were also found in the Monzas and the other GM divisions version of the Monza until 1982 when the line was replaced with the first Cavaliers.
So it wasn't that the engines were made of aluminum, just that they didn't have the steel linings and they didn't go back to iron blocks. The Vega's other major weak point was that GM cheaped out on the metal prep prior to painting to save money. The result was the body rusted out rapidly. In snowy areas, this meant the car had huge holes in the fenders right around the time the engine was really smoking and as a result, the Chevy Vega is a very scarce car today. The few that one encounters today, are usually hot rods. A popular conversion in the '70s and '80s was to drop in a small block V8. There were kits to do it and it was easy. Some of these cars survived. The V8 conversion made the car go like stink in a straight line, but ruined the handling. A better conversion was to put the V6 from the Monza in, but few people opted for this.
Ultimately, the Vega sold in large numbers and GM made a profit on all of them except the Cosworth version. However, the damage to GM's reputation was done and started the long decline to where we find ourselves today. The short comings of the Vega and Ford's Pinto, opened the door to imports like Toyota, Honda and Datsun. The management at GM at the time never took these upstarts serious enough and well, the rest is history.
