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A co-operative test program was initiated among various tire manufacturers and test facilities in order to measure passenger car tire rolling resistance with existing equipment. The results of these tests showed considerable scatter. After suitable corrections were made for test drum size, for transducer geometry and for ambient temperature, the data clustered much more closely about a single mean value. It is concluded that rolling resistance measurements using different test drum diameters and different transducer elements can be used to obtain consistent rolling resistance data provided that proper correction factors are introduced.

The paper reports a preliminary study of jets of active radicals used as igniters for lean mixtures. The jets were generated either by combustion or by electric discharge. Experiments were performed in a cylindrical steel vessel, 9 cm in diameter and 9 cm long, filled initially with either air or an ultra-lean (equivalence ratio: 0.5) methane-air mixture at atmospheric pressure and room temperature. Observations were made by schlieren photography, using a sub-microsecond spark discharge in air as a point light source. The gasdynamic properties of the jets were shown to be primarily governed by their initial velocity, while the particular process by which they were formed played, in this respect, a secondary role. The jets of radicals invariably appeared as turbulent plumes which were embedded in blast waves headed by hemispherical shock fronts.

The foundation for engine performance and emissions models is a phenomenological description of the combustion process. In this work, high speed movies and analysis of rapid compression machine experiments have been used to develop an understanding of the mechanisms that control combustion rates in the Texaco Controlled Combustion System. The rapid compression machine experiments are described and results have been interpreted to develop a description of the air motion, motion of the fuel spray and the combustion process in the Texaco engine.

The theory for the design of an auxiliary naturally aspirated, combustion (torch) chamber relates the generation of combustion turbulence, intensity of turbulence, torch chamber volume and orifice diameter to the basic combustion process. Sample calculations show how to compute the thickness of the combustion wave, the characteristic time of turbulence required to complete the combustion in a given time interval, the optimum torch chamber volume and the orifice diameter. Engine tests show that a significant reduction in HC and NOx emission levels can be achieved through the use of a torch ignition system. The combination of torch chamber geometry and torch nozzle orientation provides a control over the burn rate, rate of pressure rise, flame induced turbulence and swirl. Based on the data from the nozzles tested, the use of a swirling turbulent flame generated near the exhaust valve appears to be the most promising form of torch ignition.

A single cylinder diesel engine test facility and an air-aspirated spray burner facility have been modified and instrumented for studying diesel odor formation. Odor sampling and analysis techniques, based on the Arthur D. Little, Inc. Diesel Odor Analysis System (DOAS), have been developed and refined. Emissions mapping of the burner and the engine operating at steady state conditions, as well as transient engine conditions, are presented and discussed. The engine mappings presented indicate that operating parameters, such as injection angle, exceptionally high or low compression ratio, and exceptionally rich or lean air-fuel ratio, can have a significant effect on odor production. The burner results presented indicate that stoichiometry as well as combustion aerodynamics can strongly influence odor formation.

The engineering target was a suitable Diesel engine for the largest available luxury sedan. After consideration of various alternatives including the design of a completely new 6-cylinder engine it was decided to equip the existing naturally aspirated 5-cylinder engine presently installed in the smaller sedan and the coupe with a turbocharger. Development time and cost as well as investment could thus be minimized. This paper describes in detail the complete engine and particularly the modifications required to cope with the higher thermal and mechanical loads, the installation and adaptation of the turbocharger, the adaptation of the fuel injection pump, and the refinements of the combustion process. This work, together with suitable turbocharger characteristics due to wastegate control on the turbine side, resulted in an attractive power plant with very good stationary and transient operational behavior.

The effects on fuel economy, emissions, passenger car safety and other varaibles due to the installation of light-weight Diesel powerplants were studied. Experimental data was obtained on naturally aspirated and turbocharged Diesel engines installed in subcompact and compact passenger vehicles. The data include fuel economy as a function of engine type and horsepower, transmission layout, vehicle inerta weight, and of regulated emission constraints. Unregulated emissions have been characteristized during the course of the work. The compatibility of the Diesel engines studied with passenger car structures incorporating advanced frontal crashworthiness capabilities was analyzed and demonstrated with the Integrated Research Vehicle (IRVW).

This paper describes the development of a CVS compatible sampling system for automotive sulfate emissions. The design resulted from a consensus of ideas from EPA and industry. The system can be used with either a positive displacement pump or critical flow venturi CVS. A mist generator was developed to quantitatively inject sulfuric acid into the tunnel. While sulfate losses were acceptable using the mist generator, with actual automotive exhaust sulfate losses were much higher. The reasons for these losses were investigated. Sulfate losses in the tubing between the car and sulfate tunnel were also investigated.

This paper summarizes a laboratory effort toward reducing nine-mode cycle composite emissions and fuel consumption in a heavy-duty gasoline engine, while retaining current durability performance. Evaluations involved standard carburetors, a Dresserator inductor, a Bendix electronic fuel injection system, exhaust manifold thermal reactors, and exhaust gas recirculation, along with other components and engine operating parameters. A system consisting of electronic fuel injection, thermal reactors with air injection and exhaust gas recirculation, was assembled which met specified project goals. An oxidation catalyst was included as an add-on during the service accumulation demonstration. In addition, the driveability of this engine configuration was demonstrated.

Emissions and fuel economy have been measured for two years on a group of 56 catalyst vehicles in consumer use and maintenance. Data presented here include idle CO; mass emissions of HC, CO, NOx, sulfate, and SO2; and fuel economy. Test cycles used were the 1975 FTP, one hour 50 mph cruise, CFDS and HFET. Fuel economy data are also presented for the same vehicles for over-the-road driving from on-board totalizing fuel and engine hour meters on each car. Sulfur dioxide emissions characteristic of two identifiable modes of carburetor tune were observed upon deceleration to idle and are discussed. Catalyst activity was measured at idle, 30 and 50 mph by exhaust sampling before and after the catalyst. Although 70% of the catalysts were established to be active at 30 and 50 mph, catalyst activity at idle was observed to be much lower when CO was > 1%.

The legislation to limit the exhaust gas emissions of motor vehicles has led to the evolvement of a variety of measuring and testing procedures which differ from country to country. Our investigations of the mandatory exhaust test procedures existing in the US and in Europe result in proposals which could be a reliable basis of a world-wide harmonized legislation. The recommendations include an improved driving schedule, standardized sampling systems and the introduction of standard test equipment for matching the test cells. Furthermore, modifications of the current evaluation of certification, assembly-line, and in-use compliance testing are given.

An analytical study has been performed to investigate the use of a one-dimensional combustion model for transient premixed flames under conditions similar to those occurring in a sparkignition internal combustion engine. The model consists of the numerical integration of the basic conservation equations for mass, momentum, energy, and species with the effects of turbulence modeled by the use of a turbulent diffusivity. In order to evaluate the effects of some of the assumptions and identify the significant parameters, a simplified system consisting of constant volume adiabatic combustion was considered. With simple chemical kinetics and constant turbulent diffusivity, there are three parameters in the problem: a non-dimensional speed of sound, a non-dimensional temperature rise due to combustion, and a Damkohler parameter relating diffusion and chemical reaction rate effects. Two types of flames were modeled, a flat flame in linear coordinates and a cylindrical flame.

The performance, exhaust emissions, and fuel consumption of a White Engines, Inc. L-163-S engine were determined using a gasoline and a diesel fuel. Values of fuel economy and exhaust emissions were predicted for Environmental Protection Agency hot-start urban and highway driving cycles simulated from steady-state results. The emissions calculated for the simulated cycles were found to be similar in magnitude to the calculated before-catalyst emissions of an equally-powerful spark-ignition engine. The diesel fuel produced higher mass emission rates of unburned hydrocarbons and carbon monoxide but lower oxides of nitrogen than the gasoline which was used. Fuel consumption and exhaust mass emission rates are presented across the speed and load operating range of the engine.

A detailed analysis has been made on the Cetane Scale presently used to rate the autoignition quality of fuels. The effect of the increase in temperature and pressure, as a result of increasing the compression ratio, on the ignition delay has been theoretically and experimentally analyzed. It has been found that the ignition delay is more sensitive to air temperature than air pressure. The sensitivity increases with the drop in the cetane number of the fuel. Many techniques have been examined to modify the present cetane scale. A modified scale has been developed by raising the inlet temperature from 150°F to 350°F without changing the rest of the rating technique. The modified scale is very effective in extending the scale to zero cetane number and is able to rate the low ignition quality fuels.

When vehicle exhaust emission tests or vehicle fuel consumption measurements are performed on a chassis dynamometer, the dynamometer is usually adjusted to simulate the road experience of the vehicle. In this study, road load versus speed data were obtained from 64 light-duty vehicles. Dynamometer power absorption settings to simulate the measured road loads are computed. These dynamometer settings are regressed against vehicle frontal area and vehicle inertia weight. It is concluded that the dynamometer load settings are most accurately predicted on the basis of the vehicle frontal area. The frontal area based prediction system is then improved by separating vehicles into different classes and by including estimations of the effects of the vehicle protuberances.

Data from dynamometer tests is presented which shows the fuel consumption penalty when emission requirements constrain air-fuel ratio to near stoichiometric mixtures. This was verified on one vehicle.

A simple model of the energy required to negotiate the two Federal test cycles is described and then used as a bssis for a graphic representation of the relative energy consumption. The utility of the concept is demonstrated by comparing certification fuel economy data and projections with the aid of the relative energy consumption plot.

The potential fuel economy and exhaust emission benefits that might be obtained by smoothing the flow of traffic have been investigated. Substantial improvements in fuel economy and reductions in exhaust emissions are possible if the flow of traffic is smoothed. Traveling during the smooth flow conditions of the early morning (4 am) as compared to travel on the same urban route during highly congested flow (5 pm rush hour) resulted in a fuel economy improvement of 31% for hot-starts and 35% for cold-starts. Also, traveling during smooth flow conditions resulted in reductions in HC, CO, and NOx emission levels of 54%, 52%, and 2% respectively for hot-starts and 35%, 52%, and 13% respectively for cold-starts. The reported results were obtained by simulating traffic conditions on a chassis dynamometer.

After 50 years of parallel development and growth, a comparison of safety statistics between U.S. public highways and the General Motors Proving Ground 200 km private road system shows: the Proving Ground has approximately a five times lower accident rate, seven times lower fatality rate, thirty-five times lower injury rate, and almost nine times lower property damage rate. Accident analysis and preventive countermeasures are discussed philosophically and by practical examples. This exceptional safety record has been achieved by having trained drivers operating well-maintained vehicles on properly designed driving schedules using a road/roadside system designed for safety. All known Proving Ground accident causation factors now have operational countermeasures except sleep, and this remains a problem for which solutions are sought. “Progress: There must always be a better way.”*

This paper describes the results of a test program to evaluate various roadway disturbances present in the driving environment. The specific objectives were to pare down the list of possible roadway disturbances to the worst cases, identify handling problem areas, find meaningful response parameters and compare responses of different vehicles which might influence the results. The program provided an accident data analysis, survey questionnaire results and full scale test results which found the pavement/shoulder dropoff (requiring an edge climb maneuver) to be the most severe and most likely disturbance to result in lane exceedance. This occurs when the vehicle is scrubbing one set of tires on the shoulder edge (or encountering the edge at too shallow an angle for climb), thereby climb), thereby requiring the driver to apply a large steering deflection to get the car to climb back onto the pavement. In this case the vehicle will “spin out” if the speed is high enough.