The problem was in executing. The +Chevrolet Vega in particular had a lot of interesting details including the aluminum block engine. The GM engineers developed a block made from a high-silicon alloy. The bores were etched to expose the hard silicon giving a durable surface without the need for steel or iron sleeves. Unfortunately they used an undersized radiator that could manage the thermal loads, leading to overheating that warped the blocks.

While GM soon gave up, the same technology was eventually used by many other automakers with great success. Fortunately other innovations have worked out better in recent years.