ABSTRACT.

The Octane Requirements of Italian passenger cars are reviewed in the light of tests carried out on 150 vehicles. After a brief explanation of the experimental procedures, the adequacies of commercial Italian gasolines with respect to the demands of the various engines are discussed. Finally, some observations are made on the probable increase in compression ratio and the consequent variation in Octane Requirement.

RESUME.

Les besoins en octane des voitures italiennes sont analysés sur la base des tests effectués sur 150 automobiles. Le mémoire donne une brève deseription des méthodes expérimentales, il discute les quantités nécessaires d'essences commercia!es italiennes en ce qui concerne les besoins des différents moteurs. II présente finalement certaines observations sur l'augmentation probable des taux de compression et sur les variations en besoin d'octane qui en résultent. introduction and Scope In this paper are reported results of determinations of Octane Requirement made on the main types of Italian passenger cars. The data have been used to determine the Octane Requirement of the Italian automobile population in 1957 and also that of new cars produced in 1951, 1953, 1955 and 1957.

In the first determination it was required to establish the curve representing the percentage of the total passenger automobiles in circulation at a certain date whose requirements were satisfied by various Octane Numbers.

As it was found that no such survey had ever been published in Italy, it is thought that the present paper might be useful, both for refiners and automobile manufacturers, as a basis for appraising how far their products correspond to the needs and potentialities of the market.

Further, it is to be hoped that eventual criticism and observations by other Italian workers will provide other information on this problem so that it will be possible to establish a more reliable basis for future investigations into the Octane Requirements of the Italian automobile population.

The second treatment of the data collected concerns the Octane Requirements of new vehicles produced in the years 1951, 1953, 1955 and 1957. This second part should provide a starting point for future determinations of the same type, which, given in time to the gasoline refiners, would enable them to see whether their products can meet the demands and would permit them to provide for any necessary modifications.

In fact, if on the one hand, new models represent, especially in Italy, only a moderate percentage of the total cars in circulation, on the other hand, it is generaIly the new models which condition the future trend in the upper limit of Octane Requirements.

It is important to bear in mind the custom which is spreading in Italy of putting on the market new models derived from their predecessors, but modified in such a way that knock

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