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This study describes the development of engine test applicable to motorcycles. Due to the dramatically stringent of emission regulation, the aim of this development is to develop the engine test specifically for motorcycles based on the unconventional fuel, of which test results is comparable to field trial test results. Furthermore, this developed engine test is able to distinguish the engine oil in each performance level. Resulting in this comparison the newly development of engine test is comparable to field trial in aspects of detergency, anti-wear performance, and oil consumption.

Biodiesel is widely used as a diesel component worldwide as well as in Thailand. Even there are so many research papers studied about biodiesel combustion, performance and emission, the various sources of biodiesel and engine technologies makes it more complicated to conclude how biodiesel combustion react to the engine behavior, especially for transient state operation. Some of biodiesel user feels that the presence of biodiesel component in diesel fuel influence on poor engine driveability even only 5% V/V. While, there is a few publications comment on the low sensitivity of diesel fuel ignition delay quality when running with advance diesel common-rail DI engine. The first experiment was done on low pressure diesel combustion which represented the conventional diesel technology, aiming to study the effect of fuel injection pressure on biodiesel combustion. The results shown that, the higher content of biodiesel blended fuel has no significant effect on diesel combustion.

Diesel Dual Fuel (DDF) operation is a promising alternative engine operating mode. Previous research studies have reported a DDF engine operating under low load conditions suffers from high HC emissions, mostly Methane. The current study investigated the use of a multiple direct injection strategy for improvement of low-load DDF operation in a commonrail direct injection single-cylinder diesel engine. Natural gas was supplied at 70% of energy replacement ratio. Results indicated that depending on engine conditions, a double-pulse injection had potential for combustion control and provided an effective way to reduce NOx and methane emissions. Moreover, the double-pulse injection helped improve the combustion stability, reduce the pressure rise rate, and decrease the maximum cylinder pressure, compared to DDF operation with a single pulse injection.

The higher portion of biodiesel blended fuel will result in lower power output since biodiesel itself has lower energy input (B20 gave about 3% lower torque output at peak torque speed). In the ELR (Engine Load Response) Test Cycle, biodiesel blended fuel emitted less smoke than diesel fuel, while CO and NOx emission of biodiesel blended fuel and diesel fuel are comparable. Biodiesel particulate matter (PM) seemed to be higher than diesel fuel. In addition, additized biodiesel blended fuels (B5, B10 and B20) proved qualitative in oxidation stability, acid value, etc. Biodiesel specific lubricant confirmed its functions by evaluating the viscosity increase, fuel dilution, TAN, TBN and wear metal content during engine durability test. The used oil analysis affirmed that the lubricant could effectively be used with particular biodiesel blended fuel in advanced, heavy-duty common-rail DI diesel engines.

The diesel/natural gas engine configuration provides a potential alternative solution for PM and NOx emissions reduction from typical diesel engine operations. However, their engine operations suffer from high NMHC/methane emissions and poor engine performance, especially at light loads. By increasing the diesel pilot quantity, the performance and reduction of NMHC/methane emissions can be improved but the emission levels are still very high. Clearly, a typical DOC is not good enough to treat NMHC/methane emissions. Methane has been known as one of most stable species that is difficult to catalytically oxidize in lean burn environment and low exhaust temperatures. An aftertreatment system exclusively designed for treating methane emissions from DDF operations is therefore necessary. The current work is aimed to establish an effective computational tool in order to study the newly proposed catalytic converter system concept on treating methane from DDF operations.

The special blended fuel - gasohol E10 (RON 91) used for the test was prepared to the gasoline RON 91 specification. The test vehicles were six four-stroke motorcycles. Testing results for motorcycle emissions, performance and driveability were compared with gasoline RON 91. Furthermore, the four-stroke and two-stroke motorcycle engines were tested for their durability and performance, comparing gasoline and gasohol E10. The chemical properties of the specially blended gasohol E10 was almost the same as gasoline RON 91 except the 3% lower heating value and the lower stoichiometric air-to-fuel ratio, i.e., 14.2 for gasohol E10 and 14.6 for gasoline RON 91. The results of vehicle performance and emissions comparing gasohol E10 and gasoline RON 91 showed that gasohol E10 had better fuel economy when operating with the low to medium speed conditions.

In Thailand, exhaust emission from automobile has been one of the major pollution problems. It is known that Intake Valve Deposit (IVD) causes poor driveability and deterioration of exhaust emissions, but there has been no established test method of IVD in Thailand. Toyota 1G-FE engine was selected for an IVD test. After the evaluation of IVD from various experiment using the matrix of various engine speed and load, the combination of 3000 rpm and 50% opened throttle was determined to be the most appropriate operating condition of this IVD test. This test method has good repeatability and can differentiate IVD weight from different fuels or additives. This new test method may be considered to be the standard IVD test method for Thailand in the future.

As the consequence of air quality detenoration and the car overpopulation in Bangkok Metropolitan Area, unleaded gasoline was introduced in 1991 In using unleaded gasoline for cars with soft exhaust valve seats, their recession was found to be excessive after only 3000 - 12 000 km of usage on the highway at 120 km/h Such cars represented about 15 percent of the national car population in 1993 Using an anti-valve seat recession additive is one solution used to prevent valve seat recession An engine test simulating field conditions to evaluate additive effectiveness was implemented Potassium-based and sodium-based additives were tested and the test results led to the conclusion that the effective anti-valve seat recession additive treat rate suitable for car population and driving condition in Thailand was 10 mg of potassium or sodium per kg of fuel Unleaded gasoline with anti-valve seat recession additive has replaced leaded gasoline in Thai market as of 1995 Finally, leaded gasoline was completely phased out as of January 1, 1996 by Government regulation