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Technical Paper

Corrosion Resistance of Trim Materials

1963-01-01
630110
As the design of automobiles changed over the past seventy years, manufacturers have increased the usage of decorative trim to further enhance the beauty of styling concepts. As new trim materials were introduced and parts became more complicated in design, producers have continued their efforts to produce decorative trim parts which remain attractive during the service life of the automobile. The service performance of trim materials in several geographic locations, the use of accelerated tests to predict service performance, recent developments in improving the durability of plated parts, and requirements for producing quality exterior decorative trim are reviewed in this paper.
Technical Paper

Diesel Combustion Phenomena as Studied in Free Piston Gasifiers

1963-01-01
630449
Paper deals with abnormal combustion initially existing in the Hyprex gasifier. It was found that this was mainly due to a long ignition delay period. To correct this situation, the fuel injection system was redesigned to permit later injection at higher compression pressures with good injection characteristics.
Technical Paper

General Motors' Steam-Powered Passenger Cars - Emissions, Fuel Economy and Performance

1970-02-01
700670
Two steam-powered passenger ears have been designed, built, and tested. The SE-101 is an intermediate sport coupe incorporating the comfort and convenience features of a modern passenger car and vehicle performance comparable to a low-powered automobile. The SE-124 is a very low-power intermediate sedan with manual start and semiautomatic control. The characteristics of these cars were evaluated relative to the operational requirements of current transportation needs, with particular emphasis on exhaust emissions. Start-up time, exhaust emissions, fuel economy, acceleration, and water consumption data are presented. Although any one of these characteristics may be improved at the expense of others, it does not appear that any compromise can satisfy all of the areas required by today's motorist.
Technical Paper

Exhaust Hydrocarbon and Nitrogen Oxide Concentrations with an Ethyl Alcohol-Gasoline Fuel

1964-01-01
640651
The exhaust hydrocarbon and nitrogen oxide concentrations of a single-cylinder engine, operating on a 25% (wt.) ethyl alcohol – 75% gasoline fuel, are compared to those operating on gasoline. For comparisons at the same airfuel ratio but lower than 15.3, the addition of ethyl alcohol to gasoline reduces the exhaust hydrocarbon concentrations and increases the nitrogen oxide concentrations. At the same air-fuel ratio but higher than 15.3, the addition of ethyl alcohol reduces both the hydrocarbon and nitrogen oxide concentrations. However, tests with automobiles, operating at the same air-fuel ratio with both fuels, indicate that the addition of ethyl alcohol causes an increase in “surge” and, in some cases, results in a power loss. To overcome these performance problems, the ethyl alcohol-gasoline fuel should be operated at about the same percent theoretical air as gasoline.
Technical Paper

Dynamic Computer Techniques for Vehicle Emission Development

1972-02-01
720211
Development of engine-vehicle prototypes for low emissions and optimum fuel control characteristics has been facilitated through use of a computerized emissions test system. Simultaneous on-line sampling of exhaust species concentrations, fuel consumption, spark advance, pressures, and temperatures provides both graphical and computed outputs of several vehicle parameters that are important to development programs. On-line display of vehicle air-fuel ratio is continuously supplied. Either of two federal driving cycles (or any random driving schedule) may be employed. Dynamic calibration, range sensing, and zero-drift correction keep operator interaction and errors to a minimum. Capability for reprocessing, plotting, and/or patching stored data provides increased computational flexibility.
Technical Paper

Combustion Bomb Tests of Laser Ignition

1974-02-01
740114
Tests of laser ignition are conducted in a combustion bomb. A range of fuels is investigated comprising isooctane, cyclohexane, n-heptane, n-hexane, clear indolene, and No. 1 diesel fuel. The ignition characteristics of laser-induced sparks are compared with sparks generated with a spark plug for different air/fuel ratios. The power density required to produce laser induced sparks is investigated. Although laser ignition appears to be impractical as an ignition device because of its low efficiency and high cost, it presents some interesting possibilities compared to the standard spark plug in that the laser spark is electrodeless and can be positioned anywhere inside the combustion chamber. Its primary use appears to be as a research tool.
Technical Paper

Effects of Engine Oil Composition on the Activity of Exhaust Emissions Oxidation Catalysts

1973-02-01
730598
Platinum, palladium, and copper-chromium oxidation catalysts for exhaust emission control were exposed to exhaust gases from a steady-state engine dynamometer test in which the amount of oil consumed per unit volume of catalyst was high. When unleaded gasoline (0.004 Pb g/gal, 0.004 P g/gal) was used, conventional SE oil caused somewhat greater loss of catalyst activity than an ashless and phosphorus-free (“clean”) oil. Chemical analysis of the catalyst indicated that phosphorus from the conventional oil was probably responsible for the difference. However, a test run with low-lead (0.5 Pb g/gal, 0.004 P g/gal) gasoline and “clean” oil caused much greater catalyst activity deterioration than either of the tests with unleaded gasoline.
Technical Paper

A Rotary Engine Test to Evaluate Lubricants for Control of Rotor Deposits

1974-02-01
740159
During development of the General Motors rotary engine, the lubricant was recognized as important to its success because certain lubricants produced deposits which tended to stick both side and apex seals. Consequently, it was decided to develop a rotary engine-dynamometer test, using a Mazda engine, which could be used for lubricant evaluation. In an investigation using an SE engine oil with which there was rotary engine experience, engine operating variables and engine modifications were studied until the greatest amount of deposits were obtained in 100 h of testing. The most significant engine modifications were: omission of inner side seals, plugging of half the rotor bearing holes, pinning of oil seals, grinding of end and intermediate housings, and using a separate oil reservoir for the metering pump. Using this 100 h test procedure, three engine oils and five automatic transmission fluids were evaluated.
Technical Paper

Effects of Spark Location and Combustion Duration on Nitric Oxide and Hydrocarbon Emissions

1973-02-01
730153
This study describes the effect of spark plug location on NO and HC emissions from a single-cylinder engine with a specially modified combustion chamber. The effects of changes in combustion duration caused either by spark location, dual spark plugs, or charge dilution on NO and HC emissions were also examined. Experiments were run at constant speed, constant load, and mbt spark timing. Nitric oxide emissions were the same with the spark plug located either near the intake or exhaust valve, but were higher with the spark plug midway between the valves or with dual ignition. Hydrocarbon emissions were lowest with the spark plug nearest the exhaust valve and increased with the distance of the spark plug from the exhaust valve. With charge dilution the decrease in NO emission was isolated into a pure dilution effect and a combustion duration effect. The combustion duration effect was minimal at rich mixtures and increased with air-fuel ratio.
Technical Paper

Initial Oxidation Activity of Noble Metal Automotive Exhaust Catalysts

1973-02-01
730570
The use of relatively small catalytic converters containing alumina-supported platinum (Pt) and palladium (Pd) catalysts to control exhaust emissions of hydrocarbons (HC) and carbon monoxide (CO) was investigated in full-scale vehicle tests. Catalytic converters containing 70-80in3 of fresh catalyst were installed at two converter locations on the vehicle. Carburetion was richer than stoichiometric, with air-fuel ratios (A/F) comparable to those proposed for dual-catalyst systems containing an NOx reduction catalyst. The vehicle was equipped with exhaust manifold air injection. Homogeneous thermal reaction in the exhaust manifolds played a significant role in the overall control of HC and CO. Four Pt catalysts, three Pd catalysts, and one Pt-Pd catalyst were prepared and evaluated. Total metal loadings were varied 0.01-0.07 troy oz. Hydrocarbon conversion efficiencies varied 62-82%, measured over the 1975 cold-hot start weighted Federal Test Procedure.
Technical Paper

Continuous Secondary Air Modulation - Its Effect on Thermal Manifold Reactor Performance

1973-02-01
730493
Secondary air scheduling and average delivery rate have a great influence on the performance (carbon monoxide and hydrocarbon cleanup) of rich thermal manifold reactors. A continuously modulated secondary air system was devised to provide a tailpipe air-fuel ratio that did not change significantly with engine speed or load when a “flat” carburetion calibration was incorporated. This system involved throttling the inlet of the air pump(s) so that the air pump and engine intake pressures were equal. The continuous air modulation system was compared with an unmodulated system and a step-modulated system. The secondary air systems were investigated with both GMR “small volume” cast iron thermal reactors and Du Pont V thermal reactors on modified 350 CID V-8 engines in 1969 Chevrolet passenger vehicles. It was found that thermal reactor performance improved with each increase in control of the secondary air schedule.
Technical Paper

The Relationship of Low-Temperature Rheology to Engine Oil Pumpability

1973-02-01
730478
An analysis of oil pumpability reveals that engine oil pumping failures may occur because either the oil cannot flow under its own head to the oil screen inlet, or the oil is too viscous to flow through the screen and inlet tube fast enough to satisfy pump demands. To determine which factor is controlling, the behavior of commercial, multigraded oils was observed visually at temperatures from -40 to 0°F (-40 to - 17.8°C) in a laboratory oil pumpability test apparatus. Test results revealed that pumping failures occur by the first alternative: a hole is formed in the oil, and the surrounding oil is unable to flow into the hole fast enough to satisfy the pump. Of 14 oils tested, 7 failed to be pumped because of air binding or cavitation which developed in this manner. A model, which explains these failures in terms of yield point considerations and the low shear apparent viscosity of the oils, is proposed.
Technical Paper

DEVELOPING TRANSAXLE FLUID

1960-01-01
600069
EXTENSIVE TESTING by GM Research Laboratories has screened five promising transaxle fluids out of 32 mineral-oil-base fluids, 10 synthetic-base fluids, and numerous additive-base stock combination fluids. This paper discusses the findings of the testing and the continuing program on the five fluids. Transaxle fluids have a number of properties affecting performance, including: High-temperature viscosity. Low-temperature fluidity. Shear resistance. Friction properties. Oxidation resistance. Antifoam quality. Effect on seals. Fluid-clutch plate compatibility. Antiwear quality. Extreme-pressure quality. Antirust and anticorrosion qualities.*
Technical Paper

Seal Testing to establish quality control specifications Can Reduce “LEAKERS”

1960-01-01
600047
THIS REPORT deals with the major parameters of a seal application which affect its efficiency and life, as determined by controlled laboratory testing in CM Research Laboratories.* A. Shaft 1. Surface Roughness 2. Machining Lead B. Assembly C. Seal 1. Seal Diameter Control Trim Interference Spring Rate 2. Seal Lip Pressure Trim Interference Spring Rate Rubber Hardness Eccentricity 3. Seal Eccentricity Mold Register Assembly Trim
Technical Paper

Performance with Economy - The RamAire System

1967-02-01
670109
A novel method for the intermittent supercharging of an internal combustion engine in a vehicle is described. During full throttle operation, high pressure motivating air entrains ambient air and compresses it to an intermediate pressure in the diffuser of an air ejector. Flowing through the carburetor and into the engine, the supplemental air augments engine power, reducing vehicle acceleration time by as much as one-third. By allowing engine size to be reduced, better economy without loss of performance is possible. Typical vehicle installations are described and problem areas discussed.
Technical Paper

The GMR Sealometer A New Machine for Oil Seal Evaluation

1966-02-01
660381
The Sealometer is used for evaluating the performance of lip type oil seals and provides a dimensionless number derived from measuring the increase in temperature of a test shaft operating in a lip seal for a given time interval. With the Sealometer it is possible to study parameters that affect seal performance. As a quality control instrument, the machine provides accurate data for design. Sealometer evaluation offers a quick method of determining the life expectancy of a particular design for a particular application and eliminates the need for long life test programs.
Technical Paper

Evaluating the Effect of Fluids on Automatic Transmission Rotating Shaft Seal Elastomers

1966-02-01
660396
The Total Immersion Test (ASTM D 471) for seal elastomers, used in evaluating the compatibility of fluids and seals for automatic transmissions, does not, produce hardness and volume change results similar to those found for rotating shaft seals in service. The Tip Cycle Test was devised to provide better agreement with service results. In the test, one side of the seal is exposed to air, and the other alternately to fluid and to air-fluid vapor. Rotating shaft seals were evaluated in both car and dynamometer transmission tests, and in various bench tests. Agreement was poor between transmission tests and both the Total Immersion and the Dip Cycle Tests. Good agreement was found with the Tip Cycle Test.
Technical Paper

Fluid Composition Affects Leakage from Automatic Transmissions

1966-02-01
660397
Tests were conducted using older model cars with automatic transmissions to determine the effect of fluid composition on leakage past the rotating shaft seals. It was found that seal leakage was reduced or stopped by changing to seal-swelling fluids, and increased with seal-shrinking fluids. Leakage was also reduced by adding aromatic additives to existing fluids in the transmissions. Seal volume and hardness change results from bench tests support the car data.
Technical Paper

Correlation of Physical Properties with Performance of Polyacrylate Radial Lip Seals at -30F

1973-02-01
730051
This paper evaluates the tendency of lip seals to fracture in a test apparatus in which dynamic runout is 0.010 in and the temperature is cycled between -30 and 0 F. Seals made of eight different polyacrylate polymers were soap-sulfur cured with various types and amounts of carbon black. Physical tests included room-temperature flexibility defined by Young's modulus at small strains, standard tensile tests at room temperature, flexibility at sub-zero temperatures determined by a Gehman test, and sub-zero starting torques of the seals. Primary determinant of successful fracture resistance is a low starting torque resulting from good low-temperature flexibility. The effect of adding graphite to some of these formulations is described and some current commercially available seals are evaluated.
Technical Paper

Measurement of Air Distribution in a Multicylinder Engine by Means of a Mass Flow Probe

1973-02-01
730494
To lower emissions from a multicylinder engine, the air-fuel ratio must be optimized in all cylinders. If uniform fuel distribution is achieved, then the cylinder-to-cylinder air distribution is of particular interest. A probe system has been developed to measure mass flow rates to individual cylinders during operation of a complete engine. Fast response measurements of pressure, temperature, and flow velocity are made in the intake port near the valve during the intake portion of the cycle. High-speed collection of the large volume of data was accomplished through on-line use of an IBM 1800 computer. A V8 455 CID (7457 cm3) engine with stock intake and single exhaust system was used in the initial application of the mass flow probe. Measurements of 30-40 individual cycles were combined to calculate the mean volumetric efficiency for each cylinder.
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