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Technical Paper

STEAM-COOLING1

1925-01-01
250037
Piston friction is much the largest item of mechanical loss in an engine, amounting to fully one-half the indicated horsepower at light loads. Although opinions differ as to the most desirable temperature of the jacket-water for full-load operation, no question has arisen as to that for part load. It should be as high as possible, in order that piston friction can be reduced by keeping down the viscosity of the oil on the bearing surfaces, and that complete vaporization of the fuel may be secured. By reducing the friction of the piston and improving the vaporization, steam-cooling increases economy, which, on a number of cars of different makes, has been found to average 20 per cent more miles per gallon. Water is practically a non-conductor of heat. Boiling water, or a mixture of water and steam, is far more effective for cooling than is water that is not boiling.
Technical Paper

ANOTHER ASPECT OF CRANKCASE-OIL DILUTION

1925-01-01
250002
Wide differences of opinion are expressed by automobile builders regarding crankcase-oil dilution. The theories advanced in explanation of dilution fail to elucidate some important facts and must therefore be regarded as unsatisfactory. From a theoretical investigation, the author determines the conditions under which the vapors of various fuels condense during the compression stroke of the engine and, as a result of such analysis, presents the theory that “surface condensation,” or the aggregation of the liquid fuel-particles on the cylinder-walls, is chiefly responsible for crankcase-oil dilution. First, suggested explanations of the dilution are presented, references to previous experiments by several authorities are stated and these are discussed. The effect of jacket-water temperature is analyzed, and whether any condensation of fuel takes place during the compression stroke of a carbureter engine is debated.
Technical Paper

ENGINE-COOLING SYSTEMS AND RADIATOR CHARACTERISTICS 1

1924-01-01
240013
In the first part of the paper, a general quantitative comparison of air, water and oil-cooled cylinders is given as it relates to the subject of heat-transfer and temperature drop. Unfortunately, the discussion does not include experimental data, but the assumptions are stated clearly and a large range of values is covered in Table 2 so that any desired values can be chosen. A thorough and comprehensive discussion of the steam or the radio-condenser type of cooling is given under the headings of Steam Cooling Systems, Characteristics of Steam Cooling Systems, Cooling Capacity of Radiators Used To Condense Steam and Present State of Development. In the second part, an attempt is made to give a thorough but brief discussion of the performance or of the operating characteristics of radiators from the point of view of the car, truck or tractor designer. The cooling of aircraft engines is not considered.
Technical Paper

COOLING CAPACITY OF AUTOMOBILE RADIATORS

1923-01-01
230012
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.
Technical Paper

WINTER TESTS SHOW LOWER MILEAGE WITH HEAVY FUELS

1923-01-01
230031
Since the road-service tests of the four special fuels supplied by the Research Department, made under 1922 summer-weather conditions, gave results that were deemed inconclusive, arrangements were made for a repetition of both series of tests under the winter-weather conditions of 1923 to determine whether the relative fuel mileages for different fuels are dependent on the temperature at which car operation is conducted. The paper is a report upon the results obtained. Four fuels that bore a relation to those used in the 1922 summer tests were specified and means adopted whereby knowledge of their quality was concealed from the drivers, special emphasis being placed on crankcase-oil dilution and on the performance as reflected by the drivers' comments.
Technical Paper

ONE HUNDRED TON-MILES PER GALLON1

1923-01-01
230034
The two-fold purpose of the tests described was to acquire as many data as possible regarding the peculiar requirements of motorbuses, as viewed from the standpoint of power requirements and fuel economy, and to analyze the discrepancy found so often between the performance of an engine on the test block and the fuel economy obtained from the same engine under actual service conditions. Following a general statement of conditions to be met, and an examination of the problems of the manufacturer as to why his choice of the various units and accessories is such a vital factor in fuel economy, the improvements accomplished are enumerated, together with the reasons and inclusive of the desirable and undesirable features of carbureter specification and miscellaneous factors. The test equipment and methods are specified and discussed, the results obtained when using a steam cooling-system are presented and the general results are stated and commented upon.
Technical Paper

AIR-COOLED ENGINE DEVELOPMENT

1922-01-01
220013
The development of air-cooled engines for aircraft never made much progress until the war, when the British attempted to improve the performance of existing engines by a series of experiments leading eventually to the development of aluminum cylinders with steel liners and aluminum cylinder-heads with a steel cylinder screwed into the head. The advantages of these constructions and the disadvantages of other types are discussed. Results are reported of tests at McCook Field on a modern cylinder-design of this type showing good results, that lead to the belief that large air-cooled engines will be produced in the near future, equal in performance to water-cooled engines of the same power.
Technical Paper

RELATION OF FLUID FRICTION TO TRANSMISSION EFFICIENCY

1922-01-01
220011
That all of the variable factors of automobile friction-losses such as the quantity and viscosity of lubricants, the efficiency of worm-gearing and part-load Modifications are not appreciated, is indicated by an examination of the literature on this subject which reveals a lack of necessary data. Experiments to determine the mechanical losses, including all friction losses between the working gases in the engine and the driving-wheels of the vehicle, are described and supplementary data are included from Professor Lockwood's experiments at Yale. Three distinct possibilities for increasing the fuel economy of a motor vehicle are specified and enlarged upon, gearset experiments to secure and develop data for a four-speed gearset being then described and commented upon at length; photographs and charts illustrative of the equipment used and the resultant data are included.
Technical Paper

THE HOT-SPOT METHOD OF HEAVY-FUEL PREPARATION

1922-01-01
220034
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.
Technical Paper

MORE CAR-MILES PER GALLON OF FUEL

1922-01-01
220035
Economy tests carried out in France indicate that it is possible to obtain a larger number of miles per gallon from cars made there than from cars made in this Country. The author states that it would be well to make a careful study of the factors influencing car economy and to assure that our future car models take full advantage of all possible means of increasing their economy. Figures are presented showing the extent to which economy can be increased by changing such factors as the carbureter adjustment, time of the spark, rear-axle ratio and speed of driving. A car that normally will go 21 miles per gal. under favorable test conditions at 20 m.p.h. was increased to 43 miles per gal. at 20 m.p.h. The study is not complete but has gone far enough to demonstrate its value. This progress report is presented to stimulate thought.
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

AIR-TEMPERATURE REGULATION EFFECTS ON FUEL ECONOMY

1921-01-01
210005
Two serious problems confront the automotive industry in connection with the present fuel shortage, the securing of a much higher degree of fuel economy with existing equipment and the matter of future designs. These problems are of nearly equal importance. Because its fuel bill constitutes the second greatest item of expense for the Fifth Avenue Coach Co., operating in New York City, it is constantly experimenting with devices of various kinds to improve fuel economy. Of the different devices that it has tested, the thermostatic temperature-control for the carbureter appears to afford greatest possibilities of saving, and the author presents the results of tests of this device in actual service on motor vehicles.
Technical Paper

MOTOR-BUS TRANSPORTATION

1920-01-01
200053
Since the Fifth Avenue Coach Co. of New York is the largest successful company operating motor-buses in this country, the author gives a rather comprehensive description of this company's systems and methods, stating the three main divisions as being the engineering, mechanical and transportation departments, and presenting an organization chart. Departments concerned with finance, auditing, purchasing, publicity, claims and the like, which follow conventional lines, are not considered. The engineering, research, mechanical, repair and operating departments are then described in considerable detail. Six specific duties and responsibilities of the research department are stated and six divisions of the general procedure in carrying out overhauls for the operating department are enumerated. Regarding fuel economy, high gasoline averages from the company's standpoint mean economy, well-designed and maintained equipment, and skilled and contented operatives.
Technical Paper

INTAKE-MANIFOLD TEMPERATURES AND FUEL ECONOMY

1920-01-01
200054
Supplementing a “more miles per gallon” movement in 1919, a series of experiments outlined by the S. A. E. Committee on Utilization of Present Fuels was undertaken by the Bureau of Standards, in May, 1920, which included measurements of engine performance under conditions of both steady running and rapid acceleration with different temperatures of the intake charge secured by supplying heated air to the carbureter from a hot-air stove, by maintaining a uniformly heated intake manifold and by using a hot-spot manifold, fuel economy being determined for both part and full-throttle operation. A typical six-cylinder engine was used, having a two-port intake manifold with a minimum length of passage within the cylinder block, an exhaust manifold conveniently located for installing special exhaust openings, rather high peak-load speed and conventional general design.
Technical Paper

ENGINE DESIGN FOR MAXIMUM POWER AND FUEL ECONOMY

1920-01-01
200058
Design factors are considered from the thermodynamic standpoint only, which excludes several factors affecting power and economy. The problem of air heating includes a consideration of its influence on pressure, the consequent lowering of pressure being counteracted to some extent by the resulting improvements in carburetion and distribution and by more rapid and complete combustion; the effects of delayed combustion, with a study of the thermodynamic conditions and possible improvements; and the results that are actually obtainable from lean and rich fuel mixtures. Fuel economy is difficult because its factors conflict with those of power. The benefit of the expansion of any elastic working medium to economy is emphasized. Charts from previous papers, showing the ratio of air to fuel by weight, are referred to and discussed, best economy being obtained with mixtures leaner than those giving maximum power.
Technical Paper

TENDENCIES IN ENGINE DESIGN

1920-01-01
200013
War service demanded that gasoline engines be absolutely reliable in minor as well as major details of construction; lightness of construction was second in importance. The war scope of the gasoline engine was so wide that engineers were forced toward the solution of unexpected and unrealized problems and a vast amount of valuable data resulted. This information includes recent determination of the quantitative nature of the factors governing thermodynamic performance in respect to mean effective pressure, compression ratio and the effect of volumetric efficiency; mechanical performance in regard to mechanical efficiency and internal friction; and engine balancing.
Technical Paper

AN INTERPRETATION OF THE ENGINE-FUEL SITUATION

1919-01-01
190013
THE automotive industry is developing without due regard to the fuel situation. This situation is an integral part of the automotive field and should not be left out of account. Owing to the pressure of automotive demand, the supply of engine fuel is changing in character and price, with danger of precipitant alterations; there arises in consequence a fuel problem which cannot be adequately solved without the active participation of the automotive industry.
Technical Paper

FUEL ECONOMY OF AUTOMOTIVE ENGINES

1919-01-01
190014
THE approaching exhaustion of the petroleum supply, from which nearly all of the available internal-combustion engine fuel is produced, raises two vital questions, upon the answers to which will depend the future of the automotive industry. These are (a) what fuels are to be available, from the point of view of the engine designer and (b) how much transportation can be secured from the fuel used. It is not certain that satisfactory engines can be developed to handle a wider range of fuels than those used at present. It is therefore not clear whether the trend of development will be toward two or more different grades of fuel, or toward a single mixed fuel to be used in all engines ultimately designed to burn it.
Technical Paper

WORKING PROCESSES OF INTERNAL-COMBUSTION ENGINES

1919-01-01
190058
A new type of automotive engine should be the quest of all designing engineers. Investigation has revealed the fact that 68 per cent of all tractor engine troubles occur in magnetos, spark-plugs and carbureters, the accessories of the present-day automotive engine. Four-fifths of the fuel energy supplied is regularly wasted, yet the fuel is a liquid meeting severe requirements of volatility, etc., and is already becoming scarce and costly. In an airplane, fuel is carried by engine power. In ocean-going cargo vessels it increases available revenue space. It is at once clear that for purely practical reasons the question of fuel economy, no less than the question of the nature of the fuel, becomes momentous. What fuel will do is entirely a question of what process it is put through in the engine; in what way combustion is turned into power.
Technical Paper

ENGINE PERFORMANCE

1919-01-01
190030
EVERY plow in use should have 10 b.-hp. available. Every tractor engine should deliver continuously at least 33 hp. If the 330-cu. in. engine mentioned were as good as a Liberty airplane engine, it could deliver 57 hp. at 1000 r.p.m. The horsepower actually obtained is as follows: 41.5 in the laboratory 33.0 at the factory 29.0 when burning gasoline 23.0 when burning kerosene 21.0 with poor piston-rings 19.0 with poor spark-plugs 9.5 available at the drawbar The great engineering problem of the future lies between the 57 and the 23 hp. From 19 to 9.5 hp. is the manufacturer's problem. The main difficulties, as outlined by the figures given, lie in the combustion chamber and its ability to dissipate the surplus heat, and in the limitations of fuel. There will be no need for refiners to continue to break up the heavier fuels by processes already so successful, if by ingenuity and good understanding of thermodynamics these can be made to burn in present-day engines.
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