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This is a summary compilation and analysis of exhaust-emission results and operating parameters from forty-five heavy-duty gasoline and diesel-powered vehicles tested over a 7.24-mile road course known as the San Antonio Road Route (SARR); and, for correlative purposes, on a chassis dynamometer.(2) Exhaust samples were collected and analyzed using the Constant Volume Sampler (CVS) technique similar to that used in emission testing of light-duty vehicles. On the road course, all equipment and instrumentation were located on the vehicle while electrical power was supplied by a trailer-mounted generator. In addition to exhaust emissions, operating parameters such as vehicle speed, engine speed, manifold vacuum, and transmission gear were simultaneously measured and recorded on magnetic tape. The forty-five vehicles tested represent various model years, GVW ratings, and engine types and sizes.

Seven motorcycles, ranging in size from 100 to 1200 cm3, were tested for emissions characterization purposes. They were operated on the federal seven-mode test procedure (for 1971 and older light-duty vehicles), the federal LA-4 test procedure (for 1972 and later LDVs), and under a variety of steady-state conditions. Four of the machines tested had 4-stroke engines, and the other three had 2-stroke engines. Emissions which were measured included hydrocarbons, CO, CO2, NO, NOx, O2, aldehydes, light hydrocarbons, particulates, and smoke. Emissions of SOx were estimated on the basis of fuel consumed, and evaporative hydrocarbon losses were also estimated. Crankcase “blowby” emissions from one 4-stroke machine were measured. The impact of motorcycles on national pollutant totals was estimated, based on the test results and information from a variety of sources on national population and usage of motorcycles.

This paper describes a research program on exhaust emissions from snowmobile engines, including both emissions characterization and estimation of national emissions impact. Tests were conducted on three popular 2-stroke twins and on one rotary (Wankel) engine. Emissions that were measured included total hydrocarbons, (paraffinic) hydrocarbons by NDIR, CO, CO2, NO (by two methods), NOx, O2, aldehydes, light hydrocarbons, particulate, and smoke. Emissions of SOx were estimated on the basis of fuel consumed, and evaporative hydrocarbons were projected to be negligible for actual snowmobile operation. During emissions tests, intake air temperature was controlled to approximately -7°C (20°F), and room air at approximately 24°C (75°F) was used for engine cooling. Based on test results and the best snowmobile population and usage data available, impact of snowmobile emissions on a national scale was computed to be minimal.

To characterize exhaust emissions from water-cooled 2-stroke outboard motors (the predominant type), four new motors were tested on dynamometer stands. The engines ranged from 4-65 hp in size, and operating conditions were chosen along lines of simulated boat loading. All the measurements were taken at steady-state conditions. Emission concentrations were measured in raw exhaust gas and after the gases had been bubbled through water in a specially constructed tank. Constituents measured included hydrocarbons, CO, CO2, NO, NOx, O2, light hydrocarbons, and aldehydes. Emissions of sulfur oxides (SOx) were estimated on the basis of fuel consumed, and all the exhaust emissions data were used with available information on population and usage of motors to estimate exhaust emission factors and national exhaust emissions impact.

In an attempt to characterize emissions from small air-cooled utility engines, five gasoline-fueled models were operated over a variety of speeds and loads, and important exhaust constituents were measured. These emissions included hydrocarbons, CO, CO2, NO, O2, aldehydes, light hydrocarbons, particulates, and smoke. Emissions of SOx were estimated on the basis of the fuel consumed; evaporative losses of hydrocarbons were also estimated. The impact of small engine emissions was calculated on the basis of the test results and information on national engine populations and usage. From these data, it appears that the 50 million or more small engines currently being used account for only a small part of pollutants from all sources.

The theory of submerged jets is applied quantitatively and qualitatively to diesel fuel sprays, based on simple considerations of the inherent invalidity of the single-particle “ballistic” approach. Approximate theoretical results are obtained for penetration velocity, penetration versus time, and fuel-air ratio within the spray. Modeling experiments are discussed and the jet approach used to explain two types of diesel combustion situations-fuel entrapment by insufficient penetration in the presence of air swirl and the efficacy of the MAN process.

The design and development of an instrument for the measurement of total hydrocarbons in diesel exhaust are described, and its ability to measure steady-state and transient hydrocarbon emissions is indicated. The two-section system comprises a sampling train and flame-ionization detector and a chromatograph electrometer, recorder and backpressure regulator. A mixture of 40% H2 and 60% He was found to be the best fuel for low O2 response with the system. The method has been used for more than a year in evaluating hydrocarbon emissions from a wide variety of diesel engines under a number of typical operating conditions. The greatest advantage of the high-temperature system is its potential for expressing the total hydrocarbon content in diesel exhaust.

The major events in the development of a “pumpless” gas engine concept are related. The immediate objective of the subject program was to develop a combustion system for natural gas fueled engines which, when compared with conventional gas engines, would be operationally simpler and easier to maintain with no appreciable penalty in specific fuel consumption. The pumpless gas principle was successfully demonstrated on a single-cylinder, 2-cycle engine. The concept was then extended, with the aid of combustion photography, to a single-cylinder, 4-cycle laboratory engine. The feasibility of the concept was further demonstrated by the conversion of a commercially available 4-cycle, 4-cyl diesel engine.

Exhaust heat utilization for internal combustion engines has centered around turbosupercharging in recent years, neglecting the promising field of compounding a piston engine with a gas turbine in which, unlike turbocharging, turbine power is fed back to the engine crankshaft. The piston engine can cope with high gas pressure and temperature, whereas the gas turbine can efficiently utilize the energy at relatively low pressure and temperature and large volume flows. By compounding, this-piston engine will handle the high pressure, high temperature phase of the combustion cycle and extend the expansion ratio of the gases to atmospheric pressure by completing the low pressure, low temperature phase in the gas turbine. The marriage of the two engines will result in an outstanding power package with the highest thermal efficiency possible.

Fuel conservationists will welcome this practicable proposal for converting railroads from diesel fuel to propane gas propulsion. Propane is no newcomer to the fuel family, but the advantages of economy, simplicity of operation, minimal maintenance, and extended life of equipment, as presented in this paper, show up its unexploited and extensive potential use in all mobile units. This careful study includes experimental results and data especially applied to railroad engines, even to conversion plans for existing engines that allows an interchangeable fuel system to accommodate present supply and variable cost factors in the United States.

This paper presents the results of an investigation of the normal sources of hydrocarbon emissions of passenger cars. The sources were considered to consist of the crankcase ventilation and exhaust systems, the carburetor, and the fuel tank vent. Many studies involving the emissions from several of these sources have been conducted and reported; however, it is believed that this is the first study designed to develop emission data from all the sources of a single group of passenger cars. Although only five vehicles were used, several mechanical conditions and engine and power train configurations were examined. The largest single source of hydrocarbon emissions was found to be the exhaust, followed by the road draft tube. Relatively minor emissions were measured as a result of fuel evaporation from the carburetor and fuel tank during periods of operation and hot soak.

This paper discusses the experimental work that produced a revised military standard piston ring (conformable steel-rail oil control ring) with improved oil consumption and wear characteristics. The testing of these parameters was accelerated by the use of radio-tracer techniques. The effects of variables such as engine speed, load, jacket temperature, air-fuel ratio, intermittent starts and stops, and cyclic load operation is described. Performance characteristics of the present standard and experimental piston rings are included.