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They had an aluminum block without liners, and a cast iron head. The aluminum was a high silicon content alloy, and the surface of the cylinders was finished to expose the silicon particles and polish them. ..........

Chevrolet Vega 2300
Another case of too much too soon, the all-aluminum little Chevy was just too different for the public. In the late 1950s, GM Research Laboratories conceived an idea that a high-silicon aluminum alloy could form a hard wear surface for a cylinder bore. Working in conjunction with the Reynolds Metals Company, the material was classified as 390 die-castable hypereutectic aluminum alloy. It promised to allow the construction of an aluminum engine block without steel cylinder liners or impregnated coatings or material to prevent wear. The Vega program code-named XP-887 was announced to the public in October 1968. It was billed as a new engine for a new type of vehicle. GM research data concluded that the engine should be of an OHC design and use a carburetor similar to other Chevrolet products.

Filled with promise when put into the hands of the public, the engine suffered many issues. Overheating and the resulting warpage of the aluminum castings were common along with extreme cylinder-bore wear. Also, rubber timing belt technology was not up to standards and premature belt failure along with bent valves were common. The head gasket did not get along with the then-current anti-freeze formulations that were for cast iron engines and became a service item much like spark plugs.

The little Chevy engine never matched the reliability of the competing Ford Pinto and was replaced by a version of the 1962 Pontiac four-cylinder renamed the "Iron Duke." For 1976, the car featured a 60,000-mile warranty to try and erase the stigma of poor quality attached to the Vega.

It appeared that the Chevy designers had reservations about the 2300 since they unofficially made the engine compartment accept a traditional small-block V-8 with little fuss, making it a great enthusiast car.