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Technical Paper

ADVANTAGES OF LIGHT-WEIGHT RECIPROCATING PARTS

1922-01-01
220044
After pointing out that the general question of weight reduction is no exception to the fallacies that seem to have beset the development of the automobile from its earliest days, the author outlines briefly the problem confronting the automobile designer. The influence of the weight of the reciprocating parts on the chassis in general and the engine in particular is emphasized as being of greater importance than the actual saving in the weight of the parts themselves, it being brought out that the bearing loading due to inertia is really the factor that limits the maximum engine speed. Reference is made to the mathematical investigation by Lanchester in 1907 of the advantages of using materials of high specific-strength and the conclusions arrived at are quoted in full. A tabulation of the specific strengths of various materials used in automotive engineering practice is presented as showing the advantages of aluminum as compared with steel.
Technical Paper

A SERVICE-MAN'S ESTIMATE OF AUTOMOTIVE ENGINEERING

1922-01-01
220024
After generalizing on the need for greater consideration in automobile design for service and maintenance requirements, the author discusses the accessibility of car parts at some length with the idea of pointing out difficulties encountered by service-station mechanics when parts are inaccessible, this having a bearing also on the length of time required for repair work and the consequent increased cost to the car owner. Specific instances are given and illustrated in which improvements in design could be made to obviate trouble. These are inclusive of cylinders, cylinder blocks, pistons, bolts, cap-screws, nuts, valves, dashboard instruments and general take-up adjustment. Special emphasis is placed upon certain inaccessible parts that necessitate excessive dismantling.
Technical Paper

RECENT RESEARCH WORK ON THE INTERNAL-COMBUSTION ENGINE

1922-01-01
220001
The author describes the research work on the internal-combustion engine done recently in his laboratory in England, and presents his deductions therefrom, based upon an analysis of the evidence he has obtained to date. Fuels are discussed at length under three specific headings, many tabular data being included and commented upon, and the calculation of thermal efficiency described. Mean volatility and detonation are discussed and the author's present views regarding turbulence are stated, this being followed by a brief summary of the conclusions reached by Mr. Tizard, a colleague of the author, following recent investigations. The influence of the nature of the fuel upon detonation is presented, a lengthy discussion of the subject of stratification being given under three specific divisions, inclusive of comment upon the benefits derived from using weak fuel-mixtures.
Technical Paper

THE MEASUREMENT OF THE PROPERTY OF OILINESS

1922-01-01
220009
The term “oiliness” is defined as that property of lubricants by virtue of which one fluid gives lower coefficients of friction (generally at slow speeds or high loads) than another fluid of the same viscosity. Its importance under practical operating conditions is shown to be greater than is generally recognized. Unfortunately, however, no satisfactory method has ever been developed for the quantitative measurement of this property in comparing different lubricants.
Technical Paper

COMPRESSION-RATIO AND THERMAL EFFICIENCY OF AIRPLANE ENGINES

1921-01-01
210019
Appreciating the fundamental relation of the compression-ratio to the thermal efficiency, the National Advisory Committee for Aeronautics sponsored a comprehensive investigation of this subject at the Bureau of Standards. Every effort was made to measure the engine performance so completely as to make possible an analysis that would not only explain the results of this particular series of tests but form a sound basis for predicting the effect of changes in the compression-ratio on the thermal efficiency of any engine. The experimental work is as yet incomplete and only some of the more salient results are presented in this paper. An eight-cylinder airplane engine was used, having pistons allowing compression-ratios of 5.3, 6.3, 7.3 and 8.3. The differences in compression-ratio were effected by crowning the piston-heads by different amounts.
Technical Paper

FUEL PROBLEM IN RELATION TO ENGINEERING VIEWPOINT

1921-01-01
210016
The author states preliminarily that it is believed that never before in the history of the Society of Automotive Engineers has a single problem been so universally studied as the fuel problem that is confronting the industry today. It is also believed that never before has the industry had a problem which includes such a wide scope of work. The solution calls for the service of every class of engineer, inventor and scientist. The paper does not attempt to give highly scientific information; its real purpose is to appeal for a broader viewpoint and to give illustrations and tests which show that the solution of a problem may lie in an entirely different method than that which often becomes stereotyped by sheer usage, rather than by its specific merit. In the solution of the fuel problem we undoubtedly will have to change some of our old habits, replacing them by studiously worked out viewpoints.
Technical Paper

A SUGGESTED RULE FOR RATING RACING CARS

1921-01-01
210003
In recent years automobile engines for racing purposes have been very generally rated in accordance with their piston displacement. The natural result has been to encourage the highest possible engine speeds to attain the greatest possible piston displacement per minute. Features of engine design that have been developed under this rule include enormous valve areas, usually obtained by a multiplicity of valves, huge inlet pipes and carbureters, extreme valve-timing and very light reciprocating parts, all of which are undesirable in commercial engines. To encourage the design of engines of a type developing higher efficiency at lower engine speeds, the suggestion is made that a rule be formulated under which cars will be rated in accordance with the piston displacement per mile actually used by them. Such a rule would involve rear-wheel diameter and gear-ratio, as well as the piston displacement of the engine.
Technical Paper

RESUME OF BUREAU OF STANDARDS FUEL STUDY

1921-01-01
210004
The author states that considerable thought has been devoted recently to the relation of fuel end-point to fuel economy. It has been shown that, provided an intimate mixture of fuel-vapor and air is secured, such a mixture will not condense at the ordinary temperatures of the intake. However, on the contrary, crankcase dilution, an excess of deposited carbon, low mileage per gallon of fuel and ignition trouble are being experienced. There appears to be a discrepancy between the efficiency that should be attained and what is actually attained. To investigate this the Bureau of Standards undertook a brief series of experiments to rough out a line of procedure. Regarding compression of a dry mixture, curves are shown to illustrate that gasoline vapor compresses when “dry.” Detonation was evident when using one spark-plug and there was no detonation when using two spark-plugs.
Technical Paper

IMPORTANT FACTORS IN PISTON-RING DESIGN

1921-01-01
210050
The purpose of piston rings in an internal-combustion engine is to reduce to a minimum the leakage of gas from and the seepage of oil into the combustion-chamber. Asserting that the widely held idea that the leakage of gas past the piston can be eliminated by the use of good piston-rings is incorrect, the author states three possible paths for such gas-leakage and, after commenting upon them, discusses diagonal and lap joints and the subject of leakage with special reference to them. After considering the design of rings for gas-tightness, the author shows a fortunate mathematical relationship, in connection with the application of uniform radial pressures, regarding the bending-moment stresses. Oil leakage is treated in a similar manner and the conclusion is reached that the properties of the material used are of extreme importance.
Technical Paper

THE CONSEQUENTIAL ADVANTAGES OF WEIGHT REDUCTION

1921-01-01
210036
Stating that it is conceded by engineers that weight reduction is desirable economically but that it is not unusual to find that weight reduction is looked upon as incompatible with reliability and road-holding properties, the author outlines briefly the normal weight-distribution in an automotive vehicle and gives a short analysis of the power required to drive it having in mind the necessity of reducing the absolute friction-loss. The use of aluminum for various parts is debated, especially those in which reliability is distinctly a function of lightness and not of weight such as engine pistons, and the application is made general to cover all parts of an automobile in which the stresses are determined by road shocks and speed. The trend of design in general and recent research in particular are stated to be along the lines of weight reduction without any sacrifice of essentials.
Technical Paper

HIGH-SPEED ENGINES OF SMALL PISTON DISPLACEMENT

1921-01-01
210039
In addition to using a smaller quantity of fuel per horsepower-hour, the small high-speed internal-combustion engine has other important features of advantage which are stated. The authors outline specifications intended to secure these advantages. The high-speed racing engine designed by the authors, which won the 500-mile race on the Indianapolis Speedway in 1920, is illustrated and described in detail, its distinctive features being commented upon. The automobile should be built to a higher standard for the use of the high-speed engine. The builder should work to a greater degree of precision and, as the working parts of the engine are all light and stressed fairly highly, this necessitates the use of properly heat-treated high-grade materials. Few small cars of this type seem to give satisfaction. The authors look for further developments to counteract this in the near future.
Technical Paper

ALUMINUM PISTON DESIGN

1920-01-01
200006
The two broad divisions of aluminum pistons from a thermal standpoint are those designed to conduct the heat from the head into the skirt and thence into the cylinder walls, and those designed to partly insulate the skirt from the heat of the piston head. Pistons of the first type seem logical for heavy-duty engines; those of the second type are better suited for passenger-car engines. The objections of wear, piston slap, excessive oil consumption and crankcase dilution are stated as being the same for aluminum as for cast-iron pistons; and these statements are amplified. Piston slap is next considered and, as this can be overcome by using proper clearance, pistons of the second design tend to make this condition easier to meet. Many tests show that when too much oil is thrown into the cylinder bores, tight-fitting pistons and special rings will not completely overcome excessive oil consumption.
Technical Paper

SUPERCHARGERS AND SUPERCHARGING ENGINES

1920-01-01
200007
If at great altitudes air is supplied to the carbureter of an engine at sea-level pressure, the power developed becomes approximately the same as when the engine is running at sea level. The low atmospheric pressure and density at great altitudes offer greatly reduced resistance to high airplane speeds; hence the same power that will drive a plane at a given speed at sea level will drive it much faster at great altitudes and with approximately the same consumption of fuel per horsepower-hour. Supercharging means forcing in a charge of greater volume than that normally drawn into the cylinders by the suction of the pistons. Superchargers usually take the form of a mechanical blower or pump and the various forms of supercharger are mentioned and commented upon. Questions regarding the best location for the carbureter in supercharged engines are then considered.
Technical Paper

ADAPTING ENGINES TO THE USE OF AVAILABLE FUELS

1920-01-01
200017
Some of the salient facts regarding the character of the engine fuel marketed within the past few years are shown in accompanying curves. The desirability of operating present-day experimental cars with fuel that is the equivalent of fuel that will probably be generally marketed two years hence is stated and various methods of meeting the fuel problem are then examined. A dry fuel mixture is desired to prevent spark-plug fouling, to improve engine performance in cold weather and to minimize lubricating oil contamination by fuel which passes the pistons. Various methods of obtaining a dry mixture are then discussed, leading to a detailed description of the construction and operation of a device specially designed to accomplish such a result more successfully.
Technical Paper

COMMENTS UPON FUELS, LUBRICANTS, ENGINE AND PISTON PERFORMANCE

1920-01-01
200019
The comments the author makes regarding fuels, lubricants and engine and piston performance are suggested by pertinent points appearing in papers presented at the 1920 Annual Meeting of the Society. A list of these papers is given. The subjects upon which comments are made include salability of a car, engine balancing, pressure and chemical constitution of gasoline at the instant of ignition, the use of aluminum pistons, the success attending the various departures from orthodox construction, gasoline deposition in the crankcase and cleanness of design, as stated by Mr. Pomeroy; the performance of a finely atomized mixture of liquid gasoline and air and the contamination of lubricating oil by the fuel which passes the pistons, as discussed by Mr. Vincent; the dilution of lubricating oil in engine crankcases and the saving that can be effected by its prevention, as mentioned by Mr. Kramer; and tight-fitting pistons and special rings as presented by Mr. Gunn.
Technical Paper

PISTON-RINGS

1920-01-01
200075
The free, resilient, self-expanding, one-piece piston-ring is a product of strictly modern times. It belongs to the internal-combustion engine principally, although it is applicable to steam engines, air-compressors and pumps. Its present high state of perfection has been made possible only by the first-class material now available and the use of machine tools of precision. The author outlines the history of the gradual evolution of the modern piston-ring from the former piston-packing, giving illustrations, shows and comments upon the early types of steam pistons and then discusses piston-ring design. Piston-ring friction, the difficulties of producing rings that fit the cylinder perfectly and the shape of rings necessary to obtain approximately uniform radial pressure against the cylinder wall are considered at some length and illustrated by diagrams.
Technical Paper

IGNITION FROM THE ENGINEMAN'S VIEWPOINT

1920-01-01
200071
Ignition is discussed in a broad and non-technical way. The definition of the word ignition should be broad enough to include the complete functioning of the ignition apparatus, beginning from the point where mechanical energy is absorbed to generate current and ending with the completion of the working stroke of the engine. The ignition system includes the mechanical drive to the magneto or generator and the task imposed on the system is by no means completed when a spark has passed over the gap of the spark-plug. Ignition means the complete burning of the charge of gas in the cylinder at top dead-center, at the time the working stroke of the piston commences. The means employed to accomplish this result is the ignition system. In the present-day type of gasoline engine a spark produced by high-voltage electricity is almost universally used for ignition. This high-voltage electricity is produced by a transformer.
Technical Paper

USE OF ALUMINUM IN PRESENT AND FUTURE MOTOR CARS

1920-01-01
200038
Although aluminum is the most abundant metal in the earth's crust, it was not until the early eighties that means were discovered for reducing it from its ores in such quantities and at such cost as to make it a commercial possibility. The world immediately began to find uses for this material. Two groups developed; one, assuming for aluminum properties that it did not possess, thought that it would in time replace all other metals; the other, which, reacting from the first-mentioned view due to failures and disappointments, thought it had little use. It was afterward realized that much research was necessary to make aluminum a really commercial metal. One of the main aims of the automobile engineer is to obtain lightness combined with proper strength. The paper deals with decreasing the weight of automobiles by more extended use of aluminum alloys. The physical properties of aluminum are described in considerable detail and its varied uses are enumerated.
Technical Paper

FACTORS INVOLVED IN FUEL UTILIZATION

1920-01-01
200060
From a laboratory examination of the controlling relationships between carburetion and engine performance still in progress, the general conclusions so far reached include fuel metering characteristics, the physical structure of the charge, fuel combustion factors and details of engine design and manufacture. In every throttle-controlled engine, the variation in fuel metering for best utilization is inversely functional with the relative loading and with the compression ratio, but the nature of the fuel leaves these general relationships undisturbed. The physical structure of the charge influences largely the net engine performance and the order of variation of the best metering with change in load. Perfect homogeneity in the charge is theoretically desirable but entails losses in performance.
Technical Paper

A MODIFIED DESIGN OF CLASS B TRUCK ENGINE

1919-01-01
190031
THE design of a modification of the Class B Government standardized truck engine is presented, the principal object being a saving in weight without sacrificing either durability or safety factors. The crankcase design is rigid, but the metal is distributed so that the weight will be a minimum. The crankshafts are made of chrome-nickel steel of an elastic limit of 120,000 lb. per sq. in., which further carries out the idea of durability with low weight. The connecting-rod length is slightly more than twice that of the stroke, and this, with light-weight pistons, obviates vibration, without adding weight to the engine on account of increased cylinder height. The flywheel and bell-housing diameters were selected with a view to securing enough flywheel weight for smooth running without increasing the engine weight materially. All-steel supports reduce breakage of arms to a minimum. The manifolds are carefully designed to give economical performance, even with low-grade fuels.
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