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PISTON-ring scuffing occurs most frequently during the break-in period and has been a problem to both the automobile and ring producers, for some time. Ring coatings have been under development for several years and their general adoption by nearly all automobile companies indicates both the need for them and their effectiveness. The coatings fall into two general classes, chemical and metallic. The chemical are: Ferrox, an iron oxide; Granoseal, an iron-manganese phosphate; Graphitox and Grafotox, a zinc-iron phosphate with colloidal graphite; and Surfide, ferrous sulphide. The metallic coating is of electrolytically deposited tin. Careful tests under accelerated wear or scuffing conditions on newly finished surfaces showed that untreated rings produced twice the wear that occurred on the coated rings when only the compression rings were coated. The difference in wear was even greater when both compression and oil rings were coated properly.

This paper describes some of the more recent fuel and lubricant requirements from the standpoint of the manufacturer. Four topics are covered: oil viscosity and cranking speeds, oil composition and heavy-duty truck engine preignition, octane requirements of 1963 Chevrolet engines, and chassis lubrication developments. Heavy-duty and paspenger car engines, air-cooled and water-cooled engines are directly related to these topics.

Automotive engine output and efficiency have greatly improved over the years due to the combined efforts of the automotive and petroleum industries. As compression ratios and octane ratings of fuels have increased, the automotive engineer has been able to give the customer more for his money in either economy or performance, or a combination of both. A brief history of these developments should serve to point to the problems of the future, since octane requirements of the 1971 models have been generally reduced to enable the automobile manufacturer to meet the stringent exhaust emission standards. Since lead antiknocks are the most economical and widely used method of increasing the octane rating of gasoline, their effects on engine parameters such as durability, ORI, and emissions will be compared with lead-free gasolines. The economic impact of the change from the 94 and 100 octane number fuels to a 91 octane lead-free gasoline will be presented.

IN analyzing causes of cylinder-bore wear it is found that they fall generally into one of the following classifications: (1) Abrasion - wear due to foreign particles in the oil film. (2) Erosion - wear due to metal contact between the pistons or rings and the cylinder bore. (3) Corrosion - oxidization or chemical action of the cylinder wall by the products of combustion. Although these classifications place the three main factors in the approximate order of their importance, the conditions of operation, the design of the engine, the design of the air cleaner, the piston and ring equipment, or the lubricating oil used, may change the order completely. Four ways are described for abrasives to get into the engine, and three design factors are mentioned that will reduce cylinder wear in the presence of dust. Keeping the dirt out, however, is stated to be the only real solution, and air cleaners are recommended as the best method.