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Wire wheels, having been used exclusively on bicycles, naturally were adopted as standard by the builders of the early types of automobile. But as the automobile soon increased greatly in weight and as its builders believed that the best results could be attained by wheels of large diameter, wire wheels were found to be lacking in strength and were discarded in favor of wood wheels of the artillery type, which at that time were being imported from France. When a few years later, wire wheels again appeared on some of the English models, the prejudice against them still remained and it was not until about 1914 that they began to find favor in the industry. Drivers of racing cars, however, continued to use wire wheels because they obviated the flywheel effect and lent themselves to quicker braking and accelerating.

Stating the fundamental characteristics of the modern motor-car under the headings of performance, safety, economy, comfort and taste, the authors define these terms and discuss each basic group. The specifications of the car in which the single-eight engine is installed are given, and the reasons governing the decision to use an eight-cylinder-in-line engine are enumerated. Following a somewhat lengthy discussion of the components of engine performance, the design of the engine is given detailed consideration under its divisions of crankshaft design and the methods employed, gas distribution, the operation of the fuelizer, cylinders, valve gear and the arrangement of the accessories. Transmission design and the wearing quality of gears receive similar treatment.

Brakes have three functions: (a) maintaining a car at rest, (b) reducing the speed of a vehicle or bringing it to a stop and (c) holding a vehicle to a constant speed on a descending grade. The kinetic energy of a moving vehicle is directly proportional to the weight of the vehicle and to the square of its speed. The amount of heat produced in the braking surfaces of a vehicle descending a given grade for a given distance will be the same whether the speed be high or low, but the rate of heat production will vary inversely as the speed. In addition to the retarding effect of the braking system a braking effect is constantly present that depends on the tractive resistance of the vehicle at various speeds and on the engine itself. Wind resistance and the resistance of the engine when the throttle is closed also produce retarding effects that assist in the work of braking.

Present-day fuels are stated to be the cause of crankcase-oil dilution, due to their high end-points, and the author presents tabular data to show how end-points have risen since 1910, together with data showing the effects of various percentages of fuel dilution with relation to the Saybolt viscosities and pour-points of high-grade oils. Three divisions are made of the dilution due to mechanical defects. Contamination, not dilution, necessitates oil drainage, and this statement is elaborated. The rise of heavier-bodied oils is decried. Six specific divisions of how to avoid crankcase-oil dilution are made and emulsification is discussed, together with demulsibility and crankcase service. Five specifications are made with regard to how to avoid oil-sludging, and carbonization is given lengthy consideration. Proper oil-specification is treated, and instructions on how to avoid oil-pumping and carbon deposit are presented in eight divisions.

The author believes that the universal power unit will be direct air-cooled, but states that the direct air-cooled engine is now in the minority because, until very recently, there has not been a sufficiently broad series of established engineering facts and development work available to form a foundation for improvement. The satisfactory air-cooling of an 8 x 10-in. cylinder has been reported, and the development in a smaller cylinder of 138 lb. per sq. in. brake mean effective pressure; also, in a three-cylinder, air-cooled, radial-engine, a brake mean effective pressure of more than 125 lb. per sq. in. was developed and the engine endured beyond the ordinary expectations for water-cooled engines.

Although the proper timing of the spark is as essential as the spark itself and the electrical and mechanical devices for producing the spark have been many, little attention has been given to the study of spark-advance. An error in timing of ± 20 deg. in a low-compression engine, or of ± 15 deg. in most other engines, has been shown experimentally to cause a loss of 10 per cent from the best power and economy, provided other conditions remained the same. Hand or semi-automatic control can average hardly closer than ± 15 deg. to the correct advance because the speed and the load combinations are constantly changing on the road. Two important phases mark the spark-advance problem.

Annual Meeting Paper - The heat-dissipating properties of three types of radiator core have been investigated at the Mason Laboratory, Yale University. These include the fin-and-tube, the ribbon and the air-tube groups, so classified according to the flow of the water and the air. The ratio of the cooling surface to the volume is shown to be nearly the same in the fin-and-tube and the air-tube cores, while that of the ribbon core is somewhat greater. A formula is derived for computing the heat-transfer coefficient, which is defined as the number of heat units per hour that will pass from one square foot of surface per degree of temperature-difference between the air and the water and is the key to radiator performance, as by it almost any desired information can be obtained. When the heat-transfer coefficients have been found for a sufficiently wide range of water and air-flows the cooling capacity of a radiator can be computed for any desired condition.

Stating that most of the copying of aircraft practice in post-war car-design has proved a failure because the fundamental difference in duty has not been realized, the author proposes to show wherein the automobile designer and the engine builder can profit by the use of practice developed for air-cooled aircraft engines and, after generalizing on the main considerations involved, discourses on the simplicity of layout of the efficient air-cooled cylinder as a preface to a somewhat detailed discussion regarding cylinder design and performance, inclusive of valve location, type of finning and form of cylinder-head.

This Annual Meeting paper is a report of a series of tests conducted during the summer of 1922 by the authors at the Engineering Experiment Station of Purdue University. The work consisted of research into the operation of internal-combustion engines under comparatively high compression on ordinary gasoline without detonation. The compression-ratio of the engine was 6.75 and the compression pressure was 122 lb. per sq. in., gage. The ingoing charge was passed through a hot-spot vaporizer and thence through a cooler between the carbureter and the valves. Jacket-water temperatures between 150 and 170 deg. fahr. were carried at the outlet port of the jacket. The theory held by the authors as to the causes of detonation of the combustible charge is presented briefly. The source of the two phases of detonation encountered in this work is believed to be overheated areas in the combustion-chamber.

In the case of the internal-combustion engine, where virtually every separate portion of explosive mixture behaves differently, the usual thermodynamic interpretations of the pressure-volume indicator-card, as applied to steam engineering, have little value. In internal combustion, the pressure-volume diagram is of value only as an expression for the product of the force exerted upon the piston-top times the distance through which the piston moves. The paper (Indiana Section) begins with the fundamental phenomena and develops from them a diagram such that each fuel-mixture particle can be properly exposed for analysis during the process of combustion. This is termed the pressure-volume-quantity card, and it is described in detail and illustrated. An extended consideration of its surfaces follows, inclusive of mathematical analysis.

The authors present in this paper an explanation of gaseous detonation based upon what are considered incontrovertible laws, and show by the functioning of these well understood natural laws that gaseous detonation is a phenomenon that does not require any hypothetical assumptions to account for its existence. The physical conditions that must exist within an enclosed container when it is filled with an explosive mixture of gases and these gases are ignited are stated and analyzed mathematically, and an application of this analysis is made to the internal-combustion engine. The apparatus and the procedure are described inclusive of photographs and charts, and it is shown how the formulas can be applied (a) for constant throttle, by varying the temperature of the entering charge and (b) for constant temperature, by varying the throttle opening and the compression-ratio. The results are illustrated and discussed in some detail.

The authors state the principles governing intensive quantity-production and describe the sources and methods of handling the basic materials that compose the Ford engine-cylinder. The fundamental plan of the River Rouge plant is outlined, illustrations being used to supplement the text that explains the reasons governing the location of the various units of the plant. Details are given of the use made of conveyors with the idea of keeping everything moving. The relation of the blast furnace and coke ovens to the engine cylinder are commented upon, the powerhouse and foundry are described, and the production of the cylinder is set forth step by step.

The general method of procedure taken by the Air Service before beginning the actual design and construction of the necessary types of aircraft engine is outlined and the four steps of the development subsequent to a very complete study of existing domestic and foreign engines are stated. After checking over the layouts, if all the details are agreed upon by both the designer and the Engineering Division, the contract is placed, usually for two experimental engines, and the construction work is begun. Acceptance tests are made to demonstrate that the engine is capable of running at normal speed and firing on all cylinders. These are followed by the standard performance test made on the dynamometer at McCook Field. The results of the latter test determine whether the engine can enter the 50-hr. endurance test. The engine is then torn-down and inspected for wear. Suggested modifications are embodied in reconstructed engines which eventually fulfill the requirements.

The development of intake-manifolds in the past has been confined mainly to modifications of constructional details. Believing that the increased use of automotive equipment will lead to a demand for fuel that will result in the higher cost and lower quality of the fuel, and being convinced that the sole requirement of satisfactory operation with kerosene and mixtures of the heavier oils with alcohol and benzol is the proper preparation of the fuel in the manifold, the authors have investigated the various methods of heat application in the endeavor to produce the minimum temperature necessary for a dry mixture. Finding that this minimum temperature varied with the method of application of the heat, an analysis was made of the available methods on a functional rather than a structural basis.

The author gives a brief and purely qualitative treatment of what a vapor is, where it comes from and how it appears; the necessity of vaporizing a liquid fuel before attempting to burn it; the separate effects of the conditions that control vaporization; and the heat-balance of vaporization. This is done to summarize the conditions surrounding and controlling fuel vaporization in the cycle of operation of a throttle-controlled internal-combustion engine, fitted with an intake-manifold and a carbureter. Charts and photographs are included and commented upon, descriptions being given of actual demonstrations that were made at the time the paper was presented. The conclusion is reached that it is well to depend as little as possible upon the cylinder heat and temperature to complete the vaporization of the fuel.

The object of the paper is to consider some of the fundamental factors that affect oil consumption; it does not dwell upon the differences between lubricating systems. Beyond the fact that different oils apparently affect the oil consumption and that there is a definite relation between viscosity and oil consumption, the effect of the physical characteristics, or the quality of the oil, does not receive particular attention. The methods of testing are described and the subject is divided into (a) the controlling influence of the pistons, rings and cylinders; (b) the controlling influence of the source from which the oil is delivered to the cylinder wall.

Oil-pumping is defined and its results are mentioned. The influence of various operating conditions is brought out, particular reference being made to passenger-car service. The factors that control the rate of oil consumption are described in detail and some unusual conditions are reported. Various features of piston grooving and piston-ring design are mentioned and the effect of changes illustrated. The relative advantages of the splash and the force-feed systems as affecting the development of oil-pumping troubles are set forth and improvements suggested. A new device for reducing oil-pumping dilution troubles is described and illustrated.

The gradual trend toward overhead valves in automobile engines, as indicated by an increase in their use on American cars from 6 per cent in 1914 to 31 per cent in 1922, has been accelerated, in the opinion of the author, by their successful application to aircraft engines and by the publicity given them by their almost universal adoption on racing machines. Tractor engines recently brought out show the advantage of this construction.

The lightness and high thermal conductivity of aluminum pistons are conceded and the paper deals principally with their thermal properties, inclusive of the actual operating temperature of the pistons, the temperature distributions in the piston and the effects of the cooling-water temperature and the piston material on the piston temperature. The apparatus is illustrated and described, and charts are presented and commented upon in connection with a discussion of the results obtained. Theories affecting piston design are presented and discussed, reference being made to diagrams relating to design procedure: The work is supplementary to that done in 1921 by the authors, which they presented in a similar paper to which they refer.

The authors present and discuss the results obtained from combined road and laboratory tests made to determine the amount of power required to maintain a given car speed. The specifications of the car and its engine are stated and the variable-ratio rocker-arm of the engine is illustrated and its advantages explained, together with those of the valve-timing. The subject of manifold gas-velocity is treated in some detail, inclusive of a diagram showing the hot-spot or vaporizing device that was used. The test data are reduced to curve form, eight charts being shown. The curves include those for brake horsepower, indicated horsepower, comparative performance, performance at different throttle-openings and at different loads, fuel consumption and indicated thermal efficiencies.