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Greenhouse gas emissions (GHG) from light-duty vehicles have received attention recently because of increased focus on global warming and climate change. Relative to emissions of regulated pollutants like hydrocarbons and nitrogen oxides, nitrous oxide (N2O) emissions from all vehicles are generally very low. However, N2O is a powerful greenhouse gas, and small emissions of N2O can contribute substantially to total GHG inventories. Two fleets of different vehicle models, both meeting the current US Tier 1 emission standard, were evaluated in an effort to develop a better understanding of N2O emissions from modern three-way catalyst-equipped vehicles. Nine 1997 Ford Crown Victoria vehicles operating on clean-burning US Federal Phase 2 Reformulated Gasolines were assessed over 60,000 miles. For additional comparison, testing was also conducted with catalysts from six 1994 Toyota Camry vehicles, which had previously undergone 110,000 miles of controlled mileage accumulation.

We report on a comprehensive fuel additive study where two different detergent chemistry types, Mannichs and polyetheramines, are ranked with regard to injector deposit control in a research direct-injected gasoline (DIG) engine. The engine used was a conventional dual-sparkplug, 2.2-liter Nissan engine modified for direct injection using one of the sparkplug holes. The engine was run under 20% rich conditions to accelerate injector deposit formation. The two detergent chemistry types are shown to perform quite differently with the Mannichs showing superior performance. The Mannich detergent chemistries can reduce the DIG injector flow loss after using Howell EEE fuel from a high of 11.23% to a low of 3.14% whereas the best polyetheramine detergent chemistry tested reduced it to 8.17%. One of the Mannichs was further tested in a year 2000 specification gasoline with 150 ppm sulfur, and a North American type gasoline with 420 ppm sulfur.

The oxidation of surrogate diesel fuels composed of mixtures of three pure hydrocarbons with and without their cetane numbers chemically enhanced using 2-ethylhexyl nitrate (2-EHN) is studied in a variable pressure flow reactor over a temperature range 500 - 900 K, at 12.5 atmospheres and a fixed reaction time of 1.8 sec. Changes in both low temperature, intermediate temperature, and hot ignition chemical kinetic behavior are noted with changes in the fuel cetane number. Differences appear in the product distribution and in heat release generated in the low and intermediate temperature regimes as cetane number is increased. A chemically enhanced cetane fuel shows nearly identical oxidation characteristics to those obtained using pure fuel blends to produce the enhanced cetane value. The decomposition chemistry of 2-EHN was also studied. Pyrolysis data of 10% 2-EHN in n-heptane and toluene are reported.

A 100,000-mile fleet test in nine gasoline-powered passenger cars was carried out. The impact of motor oil phosphorus levels on engine durability, oil degradation, and exhaust emissions has been previously described. The results of additional emissions control systems studies, and measurements of the engine oil additive elements which are present on the catalysts, are now presented. These studies include conversion efficiencies for the aged catalyst at the end of the test by a combination of light-off experiments, air/fuel sweep tests, and an auto-driver FTP. The performance of the lambda sensors is also presented. The relationships between engine oil additive levels and composition and emissions systems durability is presented.

Manganese oxide deposits which are exclusively in the form of Mn3O4, a benign form of manganese, are introduced in the exhaust stream from use of MMT, an octane-enhancing, emission-reducing fuel additive. The physical and chemical effect of these deposits on catalytic converters has generated some controversy in the literature. In this paper, we will focus on the effects that manganese oxide deposits have on catalytic converters. The physical effect of these deposits on the morphology of the converters was investigated by B.E.T surface area measurements, scanning electron microscopy (SEM), and x-ray fluorescence (XRF). The chemical effect was investigated with tests using both slave-engine dynamometers and a pulse-flame combustor to probe for differences in catalyst performance. Data from an extensive vehicle fleet which was tested according to a program designed in consultation with the EPA and the automobile industry will be presented.

The use of lead-free gasoline in conventional passenger car engines poses some problems that are discussed in this paper. Under heavy-duty operation, severe exhaust valve seat wear may occur. This will eventually result in one or more valves remaining open with extremely high exhaust emissions. The combustion chamber deposits formed in the absence of lead are typically more carbonaceous. These deposits have a higher heat capacity than lead deposits and the result, after extended mileage, is higher octane number requirements for the engines operated on nonleaded gasoline. The use of aromatic blending stocks to increase the octane number of nonleaded fuels to approach the octane quality of today's leaded gasolines increases undesirable exhaust emissions. The amounts of phenol, benzaldehyde, and total aromatic aldehydes in the exhaust gas are directly proportional to the aromaticity of the fuel.

Major engine-design features of the 17.6 cu in. engine are described and engine development is traced by photographs and sectional drawings. Fuel testing with the 17.6 engine produced these results: ratings were obtained of many API-NACA pure hydrocarbons, which permitted relating variable compression-ratio results with supercharged results; Army-Navy performance numbers above 100 were established; the most sensitive fuels were indicated to be most prone to failure by preignition. The engine also contributed greatly to the development of spark plugs. The catalytic effects of spark plug electrode materials on the ignition of methyl alcohol and unleaded benzene are discussed.

THIS paper analyzes ignition-delay data and knocking characteristics of fuels. An approach to the problems of fuel sensitivity and engine severity has been made by attempting to relate the properties of the fuel-air mixture as shown from ignition-delay data and the temperatures and pressures reached by the compressed gases in an engine. The relation between octane numbers and ignition-delay characteristics of the fuels is examined. Antiknock properties of tel are investigated. It is shown that the amount of antiknock effectiveness is related to the amount of tel decomposed.

THIS paper represents a method by which the knocking characteristics of automotive engines may be compared in relation to the Research Method and Motor Method engines. The effects of many engine variables on the ratings of sensitive fuels in passenger-car engines are illustrated. These variables include compression ratio, engine speed, air density, distributor tolerances, and temperature. Direct comparisons are made of the manner in which 1955 passenger cars utilize fuel antiknock quality. It is indicated that two knock test methods must be used to achieve fuel quality control as fuel quality is recognized by engines operated in passenger cars.

A NEW research tool, the crank angle-time recorder, is described. This instrument conveniently obtains a permanent record of the time at which various combustion phenomena occur in the engine cycle. Use of the recorder in studies of normal and abnormal combustion (deposit-ignited surface ignition) has provided information of interest to both engine designer and petroleum refiner. Studies include determinations of those deposit-ignited flame fronts which result in knock, effect of fuel antiknock quality and additives on surface ignition, and resistance of fuels to surface ignition. The records obtained show that considerable variability exists in the time at which normal flame fronts arrive at an ionization gap. Some factors affecting magnitude of this variability are ignition timing, fuel-air ratio, engine throttling, changes in manifolding, and fuel type.

SEVERAL factors are involved in the answer to the question, “How do atmospheric conditions affect the ability of a fuel to satisfy the antiknock requirement of automotive engines?” As is well known, an increase in atmospheric temperature increases the octane-number requirement of engines. This paper points out, however, that this causes little change in the road octane-number ratings of commercial fuels. Increasing the absolute humidity has the opposite effect to increasing the temperature and tends to counteract the undesirable effects of changing temperature throughout the various seasons of the year. Increasing the barometric pressure or decreasing the wind velocity both increase the tendency of commercial fuels to knock. Factors indirectly related to weather conditions, such as the coolant or thermostat used in an engine, also affect the knocking tendency of a fuel.

RESULTS of an investigation directed toward determining why deposits increase antiknock requirement are discussed here. Data are presented which indicate that substantially 100% of the increase in octane-number requirement caused by deposits results from a combination of thermal and volume effects. An analysis procedure is given which indicates that deposit-thermal effects may result entirely from the heat that is stored in the deposits. Thus, the deposits absorb heat during the combustion process in one cycle and transfer it to the fresh charge during the intake and compression portions of the next cycle. The findings reported in this paper show that those engines with the smallest area of combustion-chamber surface, for a given displacement, would be expected to have the smallest thermal effects and hence should have minimum deposit effects.

DEPOSIT-induced ignition (the erratic ignition of the fuel-air mixture by combustion chamber deposits) is one of the problems hindering the development of higher compression, more efficient engines. Deposit-induced ignition results in uncontrolled combustion, which often is followed by knock. In some modern engines, the suppression of knock originating through this mechanism may require higher fuel antiknock quality than that required to suppress ordinary knock. Fuel composition and volatility have been found to affect the amount of deposit ignition. Reduction in fuel end point reduces deposit ignition. Among individual leaded hydrocarbons, aromatics produce by far the most deposit ignition, but the differences among full-boiling gasoline stocks of similar volatility do not appear to be related to their hydrocarbon-type proportions. Engine operating conditions favorable to carbon formation tend to increase deposit ignition and magnify differences among fuels.

THIS paper discusses a number of factors involved in the problem of octane-number requirement increase due to combustion-chamber deposits. A laboratory single-cylinder engine test procedure, which evaluates the effects of various fuel and oil factors, is presented with data showing its correlation with passenger-car operation under light-duty, city-driving conditions. The influence of engine operating conditions during accumulation of deposits and the importance of engine conditions selected to evaluate the magnitude of the requirement increase are illustrated. It is indicated that organic materials formed from both fuel and oil are of major importance in deposit formation. Data are presented which show that tel added to pure hydrocarbons of different chemical types may have different effects. It is shown that the carbon/hydrogen ratio of leaded pure hydrocarbons influences the amount and composition of the deposit formed.

THE striking advantages of high-compression engines - both in terms of increased power and lower fuel consumption-are emphasized here. This paper reports the results of a series of tests on a high-compression test engine arranged to permit operation at compression ratios from 6/1 to 12/1. The behavior of a variety of experimental and commercial gasolines was studied over this range of compression ratios. Bhp gains as high as 26% resulted when the compression ratio was increased from 6/1 to 12/1. Similar gains in fuel economy resulted.

DATA obtained with a cylinder of passenger-car-engine size are discussed. Compression ratios of from 5.7 to 15 to 1 have been explored rather completely with four types of combustion chamber. The investigation of this compression ratio range has included the determination of fuel economy at 1200 and 3000 rpm, with particular emphasis on part-load economy. In order to make it possible to compare results over a wide range of compression ratios, fuel economy data are presented in terms of relative thermal efficiency. Knocking data are presented in terms of air density in the combustion chamber and in terms of an empirical equivalent of air density. It is shown that, over a considerable compression ratio range, the knock-limited combustion-chamber air density on isooctane or 80 octane-20 heptane is independent of compression ratio. It is shown that turbulence has rather considerable effects in improving part-load economy and knock-limited performance.