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Mercosil Engine Block Technology
Published November 23, 1995 by Associazione Tecnica Dell'Automobile in Italy
The inherent advantages of lighter weight and better heat transfer that aluminum (and more specifically hypereutectic Al-Si alloys) can economically provide for engine blocks have long been recognized. These advantages of lighter weight and better heat transfer, regardless of their desirability in engine design and performance, have, until recently, proven insufficient justification for acceptance of aluminum engines by the U.S. automotive industry manufacturers. The situation has clearly changed, however, each of the American big 3 has an aluminum engine block currently in production and each also is aggressively planning for other aluminum engine blocks. General Motors has the Lost Foam Cast Saturn engine and the ZR-1 Corvette engine, Ford has the 4.6L Mark 8 engine and the Contour V-6 2.5L engine and Chrysler has the Viper engine. All of these aluminum engines use cast iron liners.
General Motors was clearly the technological leader in the early 1970s when they introduced the all-aluminum Vega block using alloy 390 technology. Twenty-five years later Germany is the leading producer of the all-aluminum performance blocks (by Porsche, Daimler-Benz and BMW) while U.S. automotive manufacturers are still without an all-aluminum block in production. This state of affairs may change because the Japanese have indicated that they are going to decrease the weight of the automobile by 40% by the year 2000. Thus, the cast iron block, and the aluminum block with cast iron liners, both will be unacceptable by the year 2000 for the auto-makers that are interested in gaining or maintaining market share.
The perception of the past that cylinder bores of engine blocks based on a hypereutectic Al-Si alloy technology must be high risk is absolutely not true today. This paper addresses that issue, first with Mercury Marine's production experience and second, with physical and mechanical data on the Mercosil alloy for design use