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Fuel, Lubricant and Additive Effects on Combustion Chamber Deposits

Exxon Research and Engineering Company-S. R. Kelemen, M. Siskin, H. S. Homan
University of Utah-R. J. Pugmire, M. S. Solum
Published 1998-10-19 by SAE International in United States
There is continuing interest in understanding how fuel, fuel additives, and lubricants contribute to combustion chamber deposit (CCD) weights and compositions in order to better anticipate the impact of CCD on exhaust emissions and engine performance. For this reason, we have characterized a range of CCDs from bench engines and vehicles using solid state 13C Nuclear Magnetic Resonance Spectroscopy (NMR) and X-ray Photoelectron Spectroscopy (XPS). Differences in CCD composition and structure were related to the fuel, fuel additives, and engine oil used in the test. CCDs derived from most fuels run in modern engines are predominantly organic. The fraction of aromatic carbon ranges between 24 and 74% depending on fuels and test conditions over a test length of 1,000 to 20,000 miles. These aromatic carbons exist in predominantly 1 and 2 ring structures that are independent of the amount of aromatic carbon in the CCD. These 1 and 2 ring aromatic carbon units are even present in CCD produced from non-aromatic fuels and non-aromatic lubes. The major structural difference among CCD appears in the average…
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Combustion Chamber Deposits from Base Fuel and Commercial IVD Detergent Packages

Exxon Research and Engineering Company-S. R. Kelemen, M. Siskin, W. J. Most, P. J. Kwiatek
University of Utah-R. J. Pugmire, M. S. Solum
Published 1998-10-19 by SAE International in United States
We are interested in learning how commercial intake valve detergents contribute to combustion chamber deposits (CCD) in modern vehicles run for higher mileage. It is appealing to use short mileage (<5,000 miles) tests to evaluate the CCD performance of gasoline. However, the ability to extrapolate CCD performance to higher mileage (≥10,000 miles) is uncertain because of changes in CCD formation processes. For this reason, CCD from base fuel and a commercial IVD detergent package were generated in duplicate 10,000 mile tests using four 1996 model-year vehicles. The detergent package used a polyalkylamine detergent combined with a synthetic carrier fluid and achieved 94% intake valve deposit (IVD) reduction averaged across the four vehicles tested. The CCD weights were found to be variable between repeat tests but, when pooled across the four vehicle fleet, the CCD weights were found to be statistically the same for both the additized fuel and the base fuel. The aromatic carbon, hydrogen and organic oxygen levels in the CCD were the same for base and additized fuel when pooled across the 4-car…
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THE EFFECTS OF GASOLINE OCTANE QUALITY ON VEHICLE ACCELERATION PERFORMANCE - A CRC STUDY

Exxon Research and Engineering Company-D. V. Swaynos
Amoco Oil Company-J. C. Callison
Published 1991-10-01 by SAE International in United States
A study was conducted under the auspices of the Coordinating Research Council, Inc. (CRC) to assess the potential effects of gasoline octane quality on vehicle acceleration performance. Twelve participating laboratories, representing both the oil and the automotive industries, tested a total of 182 vehicles as part of the 1989 CRC Octane Number Requirement Survey. The vehicles consisted of 78 with electronic knock control systems (knock sensors) and 104 without. All testing was performed using the 1989/1990 CRC FBRU fuel series. The results showed that acceleration performance of vehicles with knock sensors was significantly affected by gasoline octane quality. Octane effects on acceleration performance were most pronounced at maximum-throttle (detent) conditions and at octane levels below the vehicle octane requirement for trace audible knock; however, some knock-sensor vehicles did show improved acceleration performance with fuels at octane levels above the octane number requirement. Acceleration performance in non-knock-sensor vehicles was unaffected by octane quality.
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Improved Design of Onboard Control of Refueling Emissions

Exxon Research and Engineering Company-George S. Musser, Hugh F. Shannon, Albert M. Hochhauser
Published 1990-02-01 by SAE International in United States
Onboard refueling control technology has been successfully applied to two vehicles with 98+% efficiency in tests with 10.5 RVP fuel at 84° F. The Onboard system, which controls exhaust, evaporative, refueling, and so called “running losses”, was constructed out of components found in current automotive evaporative control systems. During refueling, the tank vapors are forced into the enhanced charcoal canister by a flowing liquid seal in the fillpipe. The canister was removed from the engine compartment and mounted within the vehicle frame close to the fuel tank. Each vehicle demonstrates a different possible safe location from a crash worthiness viewpoint. In order to further improve safety by preventing the expulsion of liquid gasoline upon gas cap removal, the orifices in the production tank vent lines were removed so that the fuel tank is at atmospheric pressure at all times. As modified, no significant driveability differences from production vehicles were found. Both the production and onboard vehicles met current exhaust and evaporative standards. In addition, results of laboratory simulated rollover tests showed zero fuel spillage.
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Coordinating Research Council Study of Winter Exhaust Emissions With Gasoline/Oxygenate Blends

Exxon Research and Engineering Company-William J. Most
Published 1989-09-01 by SAE International in United States
Under the auspices of the Coordinating Research Council, a program was conducted to determine the effect of gasoline/oxygenate blends on exhaust emissions (particularly carbon monoxide) for three types of emission control technologies. Tests were performed at sea level and high altitude and at temperatures of 75°F, 50°F, and 35°F. The primary fuel set consisted of a 13 psi RVP hydrocarbon-only gasoline, a hydrocarbon/11 volume percent MTBE blend, and a hydrocarbon/splash-blended 10 volume percent ethanol blend. Additionally, sea level tests were conducted with a hydrocarbon/11 volume percent ethanol matched-volatility blend and at limited conditions with a hydrocarbon/16 volume percent MTBE blend. The cars and emission control technologies tested were six 1986-88 “Adaptive Learning” closed-loop three-way catalyst systems, six 1983-86 closed-loop three-way systems without the adaptive learning capability, and four 1979-80 carbureted oxidation catalyst systems. The Adaptive Learning vehicles exhibited a small CO emissions reduction (grams/mile) at high altitude and very little response at sea level. The closed-loop, nonadaptive cars showed a variable reduction in CO with increasing fuel oxygen at high altitude and a diminished response…
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Oil-Film Thickness in a Bearing of a Fired Engine

Exxon Research and Engineering Company-M. S. Filowitz, W. H. King, J. K. Appeldoorn
Published 1982-02-01 by SAE International in United States
Relative oil-film thickness has been measured in a main bearing of a fired, single-cylinder CLR engine. The bearing is electrically insulated from the block and a small voltage impressed between the bearing and crankshaft. When film thickness becomes less than a critical value, a series of electrical discharges occurs. The relative film thickness is determined by the extent of the electrical discharge.Relative film thickness was found to increase with speed and viscosity and decrease with load as predicted from the Sommerfeld parameter. Oils containing V.I. improvers gave thinner oil films than predicted by their low-shear viscosity, but slightly thicker films than predicted by their high-shear viscosity. One oil, containing a low molecular weight polymer, was even better than its low-shear viscosity Newtonian counterpart.
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Oil Film Thickness in a Bearing of a Fired Engine Part II: The Bearing as a Capacitor

Exxon Research and Engineering Company-R. C. Craig, W. H. King, J. K. Appeldoorn
Published 1982-02-01 by SAE International in United States
A new technique has been developed to measure the actual oil film thickness in a fired engine bearing over the complete engine cycle. It involves isolating the bearing electrically from the rest of the engine, imposing a high-frequency AC voltage, and measuring the capacitance of the entire bearing. From this, the oil film thickness can be determined as a continuous function of time.The precision of the new technique is excellent and is sensitive enough to detect cycle-to-cycle variations in peak pressure, as well as such conditions as engine knock and misfire. The effect of engine load and speed and of oil viscosity is clearly noted.The overall conclusion from this work is that this technique is probably the best method currently available for determining the load carrying ability of engine oils in fired engines.
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TECHNICAL VERSUS CUSTOMER KNOCK SATISFACTION - TWO DECADES

Exxon Research and Engineering Company-E.S. Corner, A.M. Hochhauser, H.F. Shannon
Published 1978-02-01 by SAE International in United States
This paper reviews 20 years of data dealing with customer reaction to gasoline octane quality. Four technical studies and one marketing survey are covered. An analysis of the data shows that customer reaction to engine knock has not changed during this period. Agreement among three of the technical studies was good. ΔRON, the difference in Research Octane Number requirements between trained observers and customers, varied from 3.0 RON at the 50th percentile satisfaction level to 1.7 RON at the 90th percentile satisfaction level. The marketing survey shows that these values of ΔRON are a good measure of the number of customers in the marketplace who consider knock to be a problem. The fourth technical study measured ΔRON to be at least twice as large as the values in the other studies. This discrepancy is traced to the design of the questionnaire used to evaluate customer reaction to knock.
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Critical Factors Affecting Automotive Sulfate Emissions

Exxon Research and Engineering Company-B. Krause, R.A. Bouffard, T. Karmilovich, E.L. Kayle
Published 1976-02-01 by SAE International in United States
Two recently completed experimental programs provide data on four critical factors affecting automotive sulfate emissions: catalyst selectivity, catalyst age, driving mode, and gasoline sulfur level. A fifth factor, excess O2 level is discussed, but was not studied experimentally.In the first program, 20 1975 California model cars each accumulated 80 000 km on fuel containing 300 ppm sulfur. The cars used three different catalyst systems and were tested under four different test conditions: Federal Test Procedure (FTP), the Fuel Economy Test (FET), the Sulfate Emission Test (SET), and 80 km/h cruise. The results showed that SO4= emissions from one of the systems were about three times higher than SO4= emissions from the other two systems. SO4= emissions from all systems reached a peak within the first 10 000 km of the test and declined thereafter. Averaged over the 80 000 km of the test, FTP SO4= emissions from all 20 cars were half the peak value measured at 6 400 km and half EPA's previous estimate for SO4= emission from these types of vehicles. Data obtained…
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Fuel Economy Improvements Through Emissions Inspection/Maintenance

Exxon Research and Engineering Company-J. Panzer
Published 1976-02-01 by SAE International in United States
A study was carried out that permitted determination of the impact of annual emissions inspection/maintenance on fuel economy. When 50% of a car population was rejected for high emissions and tuned up, the estimated gain in fuel economy among the rejected cars was 13%. This effect was calculated by quantifying the effects of individual engine malfunctions on fuel economy and applying the results statistically to a car population whose distribution of malfunctions was known. The approach used permitted calculation of fuel economy effects when distributions of some car characteristics, driving patterns, and engine malfunctions are known. The results apply only to pre-1975 cars. It was found that repairs carried out to correct only emissions should produce about three-quarters of the fuel economy benefit achieved by a complete tune-up. When deterioration between annual inspections was considered, and 50% of the car population was rejected for high emissions, the net gain in fuel economy among the rejected cars was about 7.5%, which was significant at the 95% confidence level. The net gain in fuel economy among rejected…
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