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ALTHOUGH the use of liquefied petroleum gas in automotive vehicles dates back to the early Thirties, it is only in recent years that there has been considerable interest in this application of LPG. The author lists the factors contributing to this increasing interest as follows: 1. Rising operating costs in the bus industry. 2. The increased supply of LPG. 3. The availability of engines of higher compression ratio. The author discusses both the fuel and the vehicles in which it can be used, placing particular emphasis on cost considerations.

CONTROLLED service tests were carried out to measure the effects of combustion-chamber deposits upon octane requirement and power output of passenger-car engines. Engine power loss attributable to deposits varies rather widely with engine design. The effect of combustion chamber deposits is probably no greater than that of other factors, such as changes in ignition system characteristics.

THREE mechanisms by which combustion-chamber deposits might increase the octane requirement of an engine are discussed in this paper. These are volume, catalysis, thermal insulation. The experiments reported here indicate that the increase in compression ratio caused by deposit volume accounts, for 20-40% of the octane requirement increase, catalysis may not be a contributing factor, and the thermal insulating effect of the deposits is one of the major causes of deposit knocking harm.

THE paper outlines, first, the reason for introducing a new engine, and then comments on the considerations that led to the choice of the major features of design. Problems encountered in the development of the powerplant are discussed in some detail. A considerable amount of information on the performance characteristics of the engine is included.

A RELATIVELY easy way to correct the performance of 2-stroke diesel engines for altitude conditions is reported here. Briefly, the method consists in: 1. Obtaining the complete performance of the engine at one air density, say, sea-level conditions. 2. Plotting constant-speed fuel fishhook curves, which must be carried out to the point where power begins to fall off at overrich air/ fuel ratios. 3. Developing charts similar to that shown as Fig. 14, which contains a complete portrayal of performance for the CM 6-71 engine at 2000 rpm, both at sea level and at altitude.

THE SAE standard for involute splines, which has also been approved by several other societies, has been nine years in the making. This paper gives data and methods to supplement the standard, including intermediate tables for experimental enginering and a few new convenient formulas. A complete discussion of all the data used for the development of the involute spline standard is given here. In the standard, all dimensions given are based on production needs, but in this discussion there are tables with data and dimensions that may be applied directly to experimental or custom-built parts where gages and production checking means are not available.

THIS is the 1951 SAE Beecroft Memorial Lecture, which was presented by Mr. King after he had received the 1951 SAE David Beecroft Memorial Award for having “served the cause of highway safety with distinction.” Mr. King shows the part that should be taken by the motor vehicle bureau in the attainment of a good highway safety record. He discusses the problems of the administrator of the bureau and points out that the key to his success-and the success of the highway safety program of his state - depends upon the administration of his office, and how well it is conducted, directed and managed. Presentation of the award to Mr. King was made by SAE President Dale Roeder at the opening of the President’s Highway Safety Conference, Washington, D. C, June 13, 1951. Mr. King gave this lecture at the annual meeting of the National Safety Congress, Chicago, Oct. 13, 1951.

THIS article is based on a panel discussion held Sept. 7 by SAE Detroit Section as part of its Summer Meeting at White Sulphur Springs, W. Va. Max Roensch of the Ethyl Corp. was panel moderator. Panel speakers were: J. M. Campbell CM Research Laboratories Division S. D. Forsythe Chicago Transit Authority Leonard Raymond Socony-Vacuum Laboratories