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This paper focuses on the fuel contribution to crankcase engine oil degradation in gasoline fueled engines in view of insoluble formation. The polymerization of degraded fuel is responsible for the formation of insoluble which is considered as a possible cause of low temperature sludge in severe vehicle operating conditions. The main objective of the study is to understand the mechanism of formation of partially oxidized compounds from fuel during the combustion process, before their accumulation in the crankcase oil. A numerical method has been established to calculate the formation of partially oxidized compounds in spark ignition engines directly, by using 3D CFD. To further enable the possibility of running a large number of simulations with a realistic turn-around time, a coupled approach of 3D CFD (with simplified chemical mechanism) and 0D Kinetics (with full chemical mechanism) is proposed here.

A study of diesel fuel as a lubricant for diesel engines was conducted with the aim of dramatically reducing engine friction and eliminating the need to change the lubricating oil. A prototype single-cylinder engine modified for diesel fuel lubrication was made, and it was confirmed that firing operation is possible. Piston friction during the firing operation was reduced by modifying the shape of the cylinder liner surface to improve the retention of the lubricating oil. The study produced valid findings concerning engine lubrication, not only with diesel fuel, but also with ultra-low viscosity oil.

Precise analytical methods for characterizing diesel fuel yielding the lowest particulate emissions were developed. The methods consist of preparative-scale high pressure liquid chromatography (HPLC), field ionization mass spectrometry (FIMS), analytical-scale HPLC, and carbon-13 nuclear magnetic resonance spectrometry (13C-NMR). A diesel fuel was first separated into an aliphatic fraction and an aromatic fraction by semipreparative-scale HPLC. Then, the aliphatic fraction was analyzed by FIMS and the spectrum was compared with that of the whole fuel. The aromatic fraction was analyzed by analytical-scale HPLC to obtain the chromatogram of the aromatic hydrocarbons with a high S/N. In addition to these analyses, the fuel was analyzed by 13C-NMR to obtain the concentration of the carbon atoms of the straight chain, branched chain and aromatic-ring in hydrocarbons.

In order to investigate the effect of sulfur and distillation properties on exhaust emissions, emission tests were carried out using a California Low Emission Vehicle (LEV) in accordance with the 1975 Federal Test Procedure ('75 FTP). To study the fuel effect on the exhaust emissions from different systems, these test results were compared with the results obtained from our previous studies using a 92MY vehicle for California Tier 1 standards and a 94MY vehicle for California TLEV standards. (1)(2) First, the sulfur effect on three regulated exhaust emissions (HC, CO and NOx) was studied. As fuel sulfur was changed from 30 to 300 ppm, the exhaust emissions from the LEV increased about 20% in NMHC, 17% in CO and 46% in NOx. To investigate the recovery of the sulfur effect, the test fuel was changed to 30 ppm sulfur after the 300 ppm sulfur tests. The emission level did not recover to that of the initial 30 ppm sulfur during three repeats of the FTP.

Detergent additives in automotive gasoline fuel are mainly designed to reduce deposit formation on intake valves and fuel injectors, but it has been reported that some additives may contribute to CCD formation. Therefore, a standardized bench engine test method for CCDs needs to be developed in response to industry demands. Cooperative research between the Petroleum Association of Japan (PAJ) and the Japan Automobile Manufacturers Association, Inc. (JAMA), has led to the development of a 2.2L Honda engine dynamometer-based CCD test procedure to evaluate CCDs from fuel additives. Ten automobile manufacturers, nine petroleum companies and the Petroleum Energy Center joined the project, which underwent PAJ-JAMA round robin testing. This paper describes the CCD test development activities, which include the selection of an engine and the determination of the optimum test conditions and other test criteria.

The compositions of hydrocarbons in diesel fuel, exhaust gas and particulates were analyzed and the relationships among them were determined. It was found that the compositions of the hydrocarbons in the exhaust gas were almost the same as that of the fuel, and that the hydrocarbons in the particulates corresponded to their heavy fractions. When the engine condition was fixed, both the soluble organic fraction (SOF) and insoluble fraction ( ISF) showed positive correlation coefficients versus HC×R310, where HC denotes the hydrocarbon emission and R310 denotes the backend fraction, as measured by the fraction of fuel boiling above 310°C. On the other hand, when the engine condition was varied, ISF had negative correlation coefficients versus HC×R310, while SOF showed positive correlation coefficients.

The properties of diesel fuels were investigated in terms of particulate emissions to clarify the specification of such a diesel fuel for minimizing particulate emissions. Diesel fuels were analyzed using thin layer chromatography (TLC), and gas chromatography/mass spectrometry (GC/MS). These analysis revealed the entire composition of hydrocarbons in diesel fuels according to molecular formula. The entire composition of hydrocarbons in diesel fuels could be expressd on a three-dimensional graph: the X-axis as carbon number, the Y-axis as H/C ratio and the Z-axis as the amount of hydrocarbons of identical molecular formula. By using the graph, the properties reported so far were investigated. Also, simplified images of the fuel sprayed into a cylinder and its flame were derived from the observational results previously reported.

The effects of diesel fuel properties (aromatic content, cetane index and T90), cetane improver, oxygenates, high boiling point hydrocarbons and aromatics distribution on diesel exhaust emissions were studied under the Japanese 10-15 test cycle and the ECE+EUDC test cycle. The test vehicle was a TOYOTA COROLLA with a natural aspirated, 2.0L displacement, IDI diesel engine. It was demonstrated that particulate emissions are highly correlated with T90 and that NOx is affected by the aromatic content of fuel. A reduction in particulates emissions was observed in fuel with a lower cetane number by adding cetane improver, but this reduction was limited. Cetane improver had no effect on NOx emissions in the 45 # 60 cetane number range. Oxygenates reduced particulate emissions remarkably but had little effect on NOx emissions. A decrease in the soot in particulates was particularly observed.

The 50% and 90% distillation temperature (T50 & T90), aromatics, olefins and sulfur content are regulated in California Phase2 Reformulated Gasoline. The effects of these properties on the exhaust emissions were investigated. Twelve test fuels with little interaction between T50, T90, aromatics and olefins were prepared. Exhaust emissions were measured using a TLEV according to 1975 Federal Test Procedure (75 FTP). T50 had a large effect on exhaust HC emissions. T90 also affected HC emissions. Both increasing and decreasing T50, T90 showed increasing exhaust HC emissions. These results suggest that an optimum range of T50 and T90 exist for lowering exhaust HC emissions. The effects of sulfur on exhaust emissions were also investigated. A Pt/Rh type catalyst (production type) and a Pd type catalyst (prototype) were prepared. These catalysts were put on a 94MY TLEV. Increase of sulfur lead to increase of the exhaust emissions with both catalysts.

Engine dynamometer tests were conducted to evaluate the effect of detergent additives and gasoline components on Combustion Chamber Deposits (CCD). Additives with polyether amine (PEA) and with polyolefin amine (POA) chemicals were used. Three kinds of POA additives were used. Our results show that some kinds of additives and aromatics in gasoline increase CCD formation. Different polyolefin detergents show different tendency of CCD formation. The amount of CCD showed good relationship with the unwashed gum level of the gasoline. In general, smaller dosages produce less CCD. This means that detergents which have good IVD and PFID effectiveness at smaller dosage are better with regard to CCD. We analyzed the CCD by C13-NMR, GPC and IR method. The detergent contributes to CCD. Vehicle emissions tests were carried out to evaluate the effects of CCD on exhaust emissions.

Vehicle emissions tests were conducted using a 1992 model year Toyota Camry for California under the 1975 Federal Test Procedure. Nine fuels of different composition were prepared. Effects of gasoline composition and sulfur content on tailpipe and engine-out emissions were investigated. Exhaust mass emission test results indicated that gasoline distillation properties and sulfur content have large effect on non-methane organic gas emissions. Furthermore, fuel, engine-out, and tailpipe hydrocarbons were speciated and the relationship between fuel and exhaust specific ozone reactivity analyzed. From these studies, it is concluded that aromatics are the largest contributor to the specific ozone reactivity of exhaust emissions and these aromatics, in emissions, are mainly unburned and partly oxidized aromatics from the fuel. Fuel MTBE correlates with exhaust olefins and oxygenates.

Quality control of gasoline constituents and its effect on the Intake Valve Deposits (IVD) has become a recent issue. In this paper, the effects of gasoline and oil quality on intake valve deposits were investigated using an Intake Valve Deposit Test Bench and a Sludge Simulator. The deposit formation from the gasoline maximized at an intake valve temperature of approximately 160 °C, and the deposits formed from the engine oil were maximum at approximately 250 °C. Therefore, the contribution of the gasoline or the engine oil appears to depend on the engine conditions. The gasoline which contains MTBE or ethanol with no detergent additive slightly increases the deposition amount. The gasoline with a superior detergent significantly decreases the deposition amount even when MTBE or ethanol is blended in the gasoline. Appropriate detergent fuel additive retards the oil deterioration.

In response to various reformulated gasoline regulations, several studies have been conducted to evaluate the relationship between fuel properties and vehicle exhaust emissions. These studies, however, have focused on the fuel effect and have not examined the most promising advanced technology emission control systems on low emission vehicles. Toyota's reformulated gasoline research first set out to study the effect fuel compositions has on 2 different emission control systems. On both systems, non-methane hydrocarbon (NMHC) emissions were significantly affected by the 50% and 90% distillation temperature (T50 and T90). A correlation was also found exhaust olefine content and the amount of MTBE contained in the fuel. Research was also conducted on the specific ozone reactivity (SOR) of exhaust hydrocarbons. Various fuels with similar specifications but blended from different feedstocks were evaluated.

Fifty percent distillation temperature (T50) can be used as a warm-up driveability indicator for a hydrocarbon-type gasoline. MTBE-blended gasoline, however, provides poorer driveability than a hydrocarbon-type gasoline with the same T50. The purposes of this paper are to examine the reason for poor engine driveability caused by MTBE-blended gasolines, and to propose a new driveability indicator for gasolines including MTBE-blended gasolines. The static and dynamic evaporation characteristics of MTBE-blended gasolines such as the evaporation rate and the behavior of each component during evaporation were analyzed mainly by using Gas Chromatography/Mass Spectrometry. The results of the analysis show that the MTBE concentration in the vapor, evaporated at ambient temperature (e.g. 24°C), is higher than that in the original gasoline. Accordingly, the fuel vapor with enriched MTBE flows into the combustion chamber of an engine just after the throttle valve is opened.

The effects of methanol/cosolvent/gasoline blends on hot weather driveability are surveyed. Results show that startability after engine-off soak drastically deteriorates in an EFI vehicle. By observing the behavior of the fuel in the delivery pipe during hot-start testing and the injected fuel spray shape at high fuel temperature, the authors confirmed that the main cause of this malfunction was the vapor lock in the injector nozzle. The relationship between hot weather driveability and fuel properties is discussed. The gasoline volatility expression commonly used to indicate deterioration in hot weather driveability was found to underestimate the increase in volatility of blended fuels at higher temperatures. A suggestion is made for a modification to the expression to include the effects of methanol blending on volatility characteristics at high temperatures so that EFI vehicle hot-startability may be predicted.

In many countries, cetane number and distillation properties of diesel fuel have been changing, thus affecting the performance of diesel engines. This paper describes investigations made on the effect of diesel fuel quality on white smoke (one of the important emissions of diesel engines). The result of simple laboratory tests simulating high altitude conditions plus field tests using three types of disel engines supplied with various types of diesel fuels is given. It was found that white smoke appearing tendency correlated best with cetane number and the 90 percent distillation point of the fuel. The field tests performed at high altitude correlated well with the simple laboratory tests.

A methanol fueled, lean burn system has been developed to improve both specific fuel consumption and NOx emissions. A 1.6L four-cylinder engine with increased compression ratio has been used to develop this system. Three major components of the Toyota Lean Combustion System (T-LCS) have been applied: (1) A helical port with a swirl control valve (2) A lean mixture sensor (3) Timed, multi-point fuel injection. A 2250 lb. Inertia Weight test vehicle has been fitted with this engine, and fuel system materials have been modified. This methanol, lean burn system has improved the fuel economy by about 12% still satisfying the 1986 emission standards of the U.S.A. and Japan. Aldehyde emissions have also been evaluated.