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Technical Paper

Atmospheric Humidity and Engine Performance

1929-01-01
290033
SO-CALLED correction factors to compensate for variations in atmospheric temperature and pressure have been in practical use in connection with engine testing; but the influence of the varying amount of aqueous vapor present in the atmosphere has not had sufficient consideration. The author submits brief test-data indicative of the effect of humidity on some factors of engine performance and of the feasibility of using rational power-correction factors. By assigning due importance to the effect of humidity, he believes that a more satisfactory analysis of car and of engine performance can be obtained. Using a single-cylinder engine operated at full throttle and 1000 r.p.m. under stabilized conditions, tests were made observing maximum power, air-flow, fuel-flow, detonation and spark-advance requirements over a wide range of relative humidity for an air-intake temperature of 100 deg. fahr. Curves made from the data obtained are given and discussed.
Technical Paper

The Cooperative Fuel Research and Its Results

1929-01-01
290032
Herein Dr. Dickinson reviews briefly the causes leading to birth of the Cooperative Fuel Research, the appointment of the joint steering committee to confer on program and pass upon results, the progress made in the several phases of the work, and the projects now engaging attention. An outstanding feature has been the development of harmony and cooperation among engineers of the petroleum and the automotive industries. Mutual adaptation of the fuel and the engine to each other has been the guiding principle in the work, to the end of National economy and internal-combustion engine efficiency. Projects undertaken include the determination of the grade of gasoline that affords the maximum number of car-miles per barrel of crude oil; the causes of and remedies for crankcase-oil dilution; the effect of initial volatility on starting, acceleration and general behavior of the engine; and measurement of the detonating characteristics of a fuel.
Technical Paper

High Compression and Antiknock Fuels

1929-01-01
290035
THIS paper is an analysis of the economic value of the use of high compression, from the viewpoints of fuel cost, carbon-removal cost and engine performance. Charts and tables, based on ranges of fuel cost, compression ratio and cost of carbon removal, and on assumed increases in economy from the higher compression, are used to evaluate the economies that can be effected under these assumptions. The same methods can be applied with actual data to determine the economic value of a doped or improved fuel that makes high compression without detonation possible. Methods are given also that will show the car designer what gains in power can be made by an increase in the compression. Attention is called to the fact that improvement in fuel economy under these conditions may not be so great as expected unless it is accompanied by a change in gear ratio.
Technical Paper

Effect of a Centrifugal Supercharger on Fuel Vaporization

1929-01-01
290037
SUPPLEMENTING the results of an investigation at the Massachusetts Institute of Technology on supercharging a single-cylinder automobile engine which were presented at the 1928 Annual Meeting, this paper reports a study that was made to determine whether the mechanical action of a high-speed centrifugal supercharger improves engine performance by increasing the degree of atomization and vaporization of the fuel in the inlet manifold. While changes in the degree of fuel atomization and vaporization might be measured directly by sampling the gases as they pass to each cylinder, an indirect evaluation of these changes by measuring their effect on engine performance was considered more practicable. Tests were made on a six-cylinder automobile engine connected to an electric cradle-dynamometer.
Technical Paper

Carbon Deposits with Heavy-Duty Engines

1929-01-01
290039
THE present paper, which is an extension of previous work done at the Mellon Institute of Industrial Research in connection with carbon deposits from lubricating oils, deals with the results of tests made on heavy-duty engines in actual service. In making these tests 18 sleeve-valve-engine motorcoaches of the Pittsburgh Motor Coach Co. were used. These were divided into three groups of six vehicles each; the first group was lubricated with a paraffin-base oil of normally high carbon-residue value; the second, with a paraffin-base oil of extremely low carbon-residue value; and the third, with a typical naphthene oil. The fuel was an average grade of motor gasoline. In general, no deviation was made from the regular maintenance practice but all steps of maintenance and servicing were under the supervision of the authors.
Technical Paper

The Effect of Gum in Gasoline

1929-01-01
290036
THIS PAPER is divided in two parts. The first part is devoted to engine tests made on gasolines having different gum contents. The tests made indicate the quantity of gum that can be tolerated in a motor fuel before it will noticeably affect engine operation. It was found that only the actually dissolved or preformed gum in a gasoline at the time of use directly affects engine operation. The gum usually collects on the hot parts of the intake system, particularly the inlet valve. Photographs showing the condition of the inlet valve and cylinder-head of the test engine are reproduced. Also, in the first part, the gum-forming tendency of fuels that are stored for some time prior to use is discussed. The second part of the paper, consisting of the appendix, takes up the causes and methods of testing gasoline for gum.
Technical Paper

Ignition Requirements for High-Compression Engines

1929-01-01
290038
ADVENT of engines operating at higher compression and higher speed than engines used a few years ago in automotive vehicles has necessitated refinement of all engine accessories, including the ignition equipment. It is necessary that the ignition units give unfailing performance at top speed of the engine without sacrifice of long life of the units. Storage-battery ignition, with a generator as a source of energy, is used almost universally in this Country today, and is asserted to be the cheapest, simplest, easiest to service and most reliable system known for vehicles in which a storage battery is required for starting, lighting and other purposes. The electrical circuit used in the ignition system of automobiles today is almost identical with that designed for the 1912-model Cadillac, which was equipped with the Delco electrical engine-starter, except for refinements and greater reliability.
Technical Paper

Vapor-Pressure Data on Motor Gasolines

1929-01-01
290026
THE REPORT deals specifically with that part of the Bureau of Standards' program involving vapor-pressure measurements. A description is given of a method and apparatus for the removal of dissolved gases from dried gasolines, without appreciably affecting the propane content and without otherwise changing their composition. Vapor-pressure measurements with a small bubble of vapor present have been made on 10 motor gasolines over a considerable temperature range. Log p, 1/T plots of these data were found to be linear in the case of all the fuels within 1 to 2 mm. on the average, p representing the pressure and T the absolute temperature. The normal bubble-points (p = 760 mm.) of the 10 gasolines were shown to be equal to the 10-per cent A.S.T.M. temperatures, corrected for loss, within the accuracy of determining the latter.
Technical Paper

Present Status of Equilibrium-Volatility Work at Bureau of Standards

1929-01-01
290029
THIS paper is a concluding report on that phase of the equilibrium-volatility work at the Bureau of Standards which is applicable to engine performance as affected by vaporization in the manifold. New data on bubble-points are presented and an improved method is outlined for obtaining temperatures on specific air-vapor mixtures from the experimental observations. By taking into consideration the slope of the A.S.T.M. distillation curve, the 16-1 temperature at any percentage evaporated from 0 to 100 per cent can be computed from the A.S.T.M. temperature with an average deviation of 1 deg. cent. (2 deg. fahr.) by means of simple relations which are applicable to pure hydrocarbons and hydrocarbon mixtures, of any degree of complexity, within the gasoline range. Values for other mixtures can be readily obtained from the 16-1 temperatures.
Technical Paper

Volatility Data on Natural Gasoline and Blended Fuels

1929-01-01
290028
THE extension of the equilibrium-air-distillation work of the Bureau of Standards to more volatile fuels, requiring measurements at temperatures considerably below 0 deg. cent. (32 deg. fahr.) has shown that the general relations deduced from the previous work are equally applicable to natural gasoline and to straight-run aviation-fuels and to natural-gasoline motor-fuel blends. Data are presented on three ethylether blends with gasoline which give information on the amounts of ether to be added to gasoline for starting motor-vehicle or airplane engines at various temperatures. For comparison, data on two benzene-blends are reproduced from a previous report. A study of the entire mass of volatility data has indicated certain trends of the temperature ratios with the slope of the A.S.T.M. curve and with temperature.
Technical Paper

Combustion Control by Cylinder-Head Design

1929-01-01
290016
DETONATION and shock, the two principal barriers to increased compression, are subject to a degree of control which can readily make possible the use of compression ratios in the neighborhood of 6-1 on commercial fuel without objectionable effects and without sacrifice of output. Since detonation depends primarily upon the temperature attained by the residual unburned gas, it can be controlled by combustion-chamber design which intensifies the heat transfer from the unburned gas to the walls. The shock tendency, which originates in the pressure-time characteristic of combustion, can be controlled only by deliberate incorporation of the desirable anti-shock characteristic in the chamber design by a method of calculation which is explained in detail.
Technical Paper

Dual Carburetion and Manifold Design

1929-01-01
290020
DUAL carbureters, as equipment for eight-cylinder passenger-car engines, have recently come into special prominence and, compared with a single carbureter, give a gain in power in the middle-speed range, between 1400 and 2800 r.p.m. This is an adaptation from airplane-engine practice, in which greater power-output and better distribution have been realized by multiplying carbureter units as the number of cylinders is increased. An absence of overlapping and interfering suction-strokes and the use of larger manifold-passages are apparently responsible for this gain. Tests made on a number of eight-cylinder engines of both the in-line and the V-types confirmed this gain, which was, however, unaccompanied by any particular gain in fuel economy.
Technical Paper

The Packard X 24-Cylinder 1500-Hp. Water-Cooled Aircraft Engine

1928-01-01
280064
AFTER outlining the history of development of the Packard X engine, the author states the legitimate position in aviation deserved by the water-cooled aviation-engine of this type and predicts large increases in the size, speed and carrying capacity of airplanes within the near future. Passing then to a discussion of the important features of the X-type engine, various illustrations of its parts are commented upon. The cylinders are built-up from steel forgings, with all welds arranged so as to be subjected to no excessive alternating stresses. The novel features of this cylinder design lie in the fact that the valve seats are entirely surrounded by water and that water space is provided above the combustion-chamber and below the top plate of the cylinder. The cylinder-head is extremely rigid, resisting deflection and assuring the maximum integrity of valve seats. The valve ports are machined integrally with the cylinder-head and are not welded thereto as in the Liberty engine.
Technical Paper

Design and Operation of Modern Garages

1928-01-01
280070
THE design of the modern multi-story urban garage, commonly built of reinforced concrete, is based largely on arrangements for the vertical movement of individual cars at higher speed than prevailed in the garages of the older types, or the vertical movement of a greater number of cars at the same speed, according to the author. Basic considerations affecting the design are location, type of district, capacity, and method of vertical movement. Location on a main thoroughfare is advocated. The location in several typical districts, such as retail-shopping, office-building, hotel and club, theater and amusement, and middle or high-class residential, are discussed in connection with the several classes of patronage and their bearing on design and equipment.
Technical Paper

Volatility Data from Gasoline Distillation Curves

1928-01-01
280005
FIRST referring to previous reports made on laboratory methods for measurement of volatility, the author states that data for a variety of gasolines, obtained by the equilibrium air-distillation method, have been analyzed recently in comparison with the distillation curves of these fuels as determined by the procedure practised by the American Society for Testing Materials. According to the author, this analysis appears to indicate a definite relationship between the results on volatility and those obtained by the standard A.S.T.M. distillation method, so that it seems possible to deduce from the latter with reasonable accuracy the information on volatility which is pertinent to satisfactory engine performance. It is stated also that volatility can be regarded as the tendency to escape into the vapor or gaseous state and this escaping tendency is determined by factors which must be precisely specified so that numerical values for volatility may have significance.
Technical Paper

Results of Two Recent Detonation Surveys1

1928-01-01
280006
THE first of the detonation surveys referred to is an extension of the survey of current methods of measuring the anti-detonation qualities of motor fuels; the second is a survey of the relative detonation characteristics of available motor fuels as determined by the routine method of fuel testing now employed at the Bureau of Standards. The survey of methods presented includes a reference to the apparatus and methods described in the 1927 report, and the information regarding laboratories Nos. 1, 2, 6, 8 and 10 is not repeated; but since the other five laboratories, Nos. 3, 4, 5, 7 and 9, use modified apparatus or methods, the paper presents information regarding them as well as similar data for other laboratories. Comparative data on the apparatus and methods described in the paper are presented in a tabulation which includes 20 laboratories. Of these laboratories, at least half rely on the listening method.
Technical Paper

Engine and Car Performance

1928-01-01
280003
AN attempt is made to show in their relative importance the more important of the major factors affecting car performance. The items dependent upon engine design that are considered are acceleration, hill-climbing ability, fuel consumption and maximum speed. The factors entering into engine and car design that are discussed are the size and speed of the engine, the compression ratio and the weight of the car. Experimental data have been used only in establishing reasonable engine and car characteristics. The effects of the changes desired were estimated on what are believed to be generally accepted bases.
Technical Paper

Comparison of Methods of Measuring Knock Characteristics of Fuels

1928-01-01
280008
NINE laboratories employing widely different methods have cooperated in the measurement of the knock characteristics of five selected motor fuels. Considerable divergencies are reported in the results obtained by different methods, particularly for certain fuels, although there is reasonable agreement for other fuels. Laboratories using the “bouncing-pin” method have shown consistent results among themselves. No system of rating the knock characteristics of fuels is in use at present by which the results of different laboratories are readily comparable. An analysis of the data obtained from the nine laboratories is included herein, and possible reasons for the divergencies are discussed. First reviewing the circumstances that led to the investigation reported in his paper, the author names the laboratories which cooperated, describes the sample fuels and how they were prepared, and outlines the method or methods practised by each laboratory and the equipment used.
Technical Paper

Present Tendencies in Motor-Fuel Quality

1928-01-01
280009
WE are entering a period in which the refiner is making a conscientious effort to give his fuel high antiknock value and such effective volatility that it will give superior performance in any automobile engine in which it is used. The present tendency is away from the misleading values such as color and gravity. Ease of starting and good acceleration, particularly of a cold engine, demand high partial volatility even more than antiknock value, while the development of maximum power and a high fuel efficiency in modern engines supplying a large amount of heat to the mixture demand a relatively high end-point in the distillation test. The author discusses the difficulties of using fuels possessing these characteristics in such engines, and indicates the desirability of the automotive and the oil industries cooperating in finding a solution of their joint problem of suiting the engines and the fuels to each other.
Technical Paper

Data on Machinability and Wear of Cast Iron

1928-01-01
280022
THE hardness or chemical composition of an iron is, by itself, no indication of the wearing property and machinability of the iron. Irons containing a large amount of free ferrite have been found to wear rapidly, whereas others having considerable pearlite or sorbite in their structure show good wearing properties. The presence in cylinder-blocks of excess-carbide spots or of phosphides of high phosphorus-content is deleterious, because such spots wear in relief and the material ultimately breaks out, acting as an abrasive that scores the surfaces. Causes of wear in cylinder-blocks are discussed, and nickel, or nickel and chromium, intelligently added to the iron is suggested as a means of obtaining the correct microstructure for a combination of good wearing properties and machinability.
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