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RESULTS of an experimental study of the viscosity characteristics of motor oils at low temperatures and their influence upon cranking torque and circulation within the engine are presented by the authors. At temperatures in the neighborhood of 0 deg. fahr., even oils of asphaltic origin appear to possess some plastic characteristics, while those of the mixed and paraffin-base types deviate widely from the generally accepted laws of viscous flow. Oils of these latter classes have apparent viscosities which tend to increase with decreasing shearing-stress and to become somewhat greater than might be expected from a study of their characteristics at normal temperatures. However, as resistance to cranking the engine is due mainly to oil in thin films on the cylinder walls, the relatively small temperature-viscosity coefficient of the wax-bearing oils gives them a marked advantage over those of asphaltic origin, an advantage which becomes greater as the temperature is lowered.

THE PAPER suggests a criterion for the tendency toward overheating of plain journal bearings of the high-speed type. The application of a criterion consisting of the product of oil viscosity by the square of the running speed is considered on a heat-balance basis and is compared with a series of observations of crankcase temperatures in a number of typical cars. Quoting the fact that in a plain journal bearing the coefficient of friction is a function of the term “viscosity times rate of sheer divided by unit load,” the author states the symbols and units employed and analyzes heat generation in the fluid film. An analysis of the dissipation of frictional heat is presented also, together with a discussion of the subject of bearing-temperature estimation. Curves are presented which resulted from data based on observations taken during a series of tests on a number of representative passenger-cars on the Indianapolis Speedway.

ONE method employed in a fundamental investigation of the composition of lubricating oils as it affects the viscosity characteristics has involved the synthesis of viscous oils by polymerizing a wide range of olefins with a condensing agent, such as aluminum chloride. Many thousand gallons of synthetic lubricating oils have been made within the last two or three years from olefins produced by cracking paraffin waxes. Details of the process have been published previously and hence are not included. The present paper deals with the characteristics of two such oils that have been synthesized in commercial quantities. The raw materials and the process of manufacture make these more expensive than ordinary motor oils, but their temperature-viscosity characteristics make them desirable for use in transmission and steering mechanisms and in hydraulic shock-absorbers, as they are less susceptible than the usual oil to viscosity changes with changes of temperature.

IT is recognized that volumetric efficiency-and therefore specific output - can be increased by reduction in manifold temperature, pressure drops, and the like. The present investigation has been directed at the determination of the changes in volumetric efficiency which may be obtained by fuel-volatility variations. The results of this work may be summarized briefly as follows: (1) Very substantial improvement in engine performance can be obtained by taking advantage of suitable volatility increases. (2) A given degree of improvement in the distribution characteristics of a fuel can be attained by combining “front-end” and “total” volatilities in a fairly varied manner. (3) The distribution characteristics of a gasoline can be judged satisfactorily by using the amount evaporated at 158 deg. fahr.