According to the research entitled “the innovative engine prototype powered by diesel and LPG as fuel for agricultural” in 2019 the problems found while using the engine were as follows: the accumulated heat in the auxiliary combustion chamber reached 300 C in case of gasoline engine use and a lot of black smoke in the exhaust was found at the speed higher than 1800 rpm in case of a diesel engine use. In order to extend the research and solve two foresaid problems the objectives of this study were 1) to develop an auxiliary combustion chamber for cooling 2) to develop a scalable gas-air mixing device and 3) to compare diesel and LPG consumption rates by modifying a small diesel engine Yanmar version TF120DI to install LPG fuel systems and ignition system. In addition a gas-air mixing device was modified while an auxiliary combustion chamber was developed to reduce the compression ratio to the same level as the gasoline engine for replacing the position of the original diesel fuel injector. This method could support LPG fueling only whose function was characterized by the function of a gasoline engine. The auxiliary combustion chamber could be removed and then installed a diesel injector to return using diesel fuel. From an experiment to compare the modified engine operating as a gasoline engine it was found that the temperature of the auxiliary combustion chamber and the temperature of the engine cylinder head of Honda GX160 were measured at the maximum speed of 182 C and 186 C respectively. It was found that carbon monoxide content was 0.41 % and 1315 ppm hydrocarbons. When used as a diesel engine it was found that the black smoke was exhausted at 1.5 % which was similar to the diesel engine before the modification. From the experiment of using the power engine for pumping water with an Irrigation propeller pump with the diameter of 8 inch at a constant engine speed of 1000 rpm it was found that the average diesel usage was 0.65 kg/hr or about 0.77 L/hr with the cost of 21.00 Baht/hr and if using LPG as fuel the average LPG consumption was 0.57 kg/hr with the cost of 13.71 Baht/hr which could save up to 34.71 % of costs.

Nowadays the majority of environment problem is pollution of vehicle including the noise of engine combustion. For this reason this thesis aims to compare and study the parameters which affect noise reduction on exhaust pipe. Not only reduce the noise pollution but also maintain the efficiency of the engine. These two substances must be considered. Therefore the researcher emphasized to study the parameters on 3 types of muffler with an equal volume: direct reverse and offset type of mufflers. Initiated by data collection the pressure and the velocity in muffler at the speed of engine at 1000 RPM (slow-running engine mode) and 4000 RPM (maximum running engine mode) were investigated. The data were applied into the program that called “SolidWorks” in order to study parameters. In this step the relation between the pressure and velocity of exhaust were represented. In addition the muffler models were selected to manufacture and test by the standard of The Department of Land Transport. As a result there are two major parameters of the muffler. Firstly the metamorphism of the exhaust gas flow direction pleasurably causes the lower noise at the speed of engine at 1000 RPM. Besides an increase of the flow gas distance can diminish noise at the speed of engine at 4000 RPM as well. However this muffler models were tested under the working mode of catalytic device that is standard equipment for automotive vehicles.

The objective of this work is to investigate the effects of water injection on performance of 5-stroke SI engine converted from the conventional 4-stroke SI engine.The cylinder head of the 2ndand3rd cylinder was modified and connected to each other to be the ultra-expansion stroke or second expansion stroke (5thstroke). The engine was performed on a dynamometer at different engine speeds and loads of 1500 to 3000 rpm and 25% to 75% of full load respectively. The water was injected during the second expansion stroke (5th stroke). Fuel and air consumptions engine torque rotational speed air/fuel ratio and temperatures of intake air engine oil cooling water and exhaust gas were recorded to use for calculating brake specific water and exhaust gas were recorded to use for calculating brake specific fuel consumption (BSFC) and engine efficiency. The results showed that at low engine speed of 1500 rpm for all loads the water injection improves BSFC and the engine efficiency by 26% and 3.3% respectively. However a large amount of injected water shows insignificant improvement on BSFC and the engine efficiency due to short residence time especially at high engine speed. The deterioration of engine oil can be observed after test. These findings are relevant to engine design or modification especially at low engine speed.

Presently the rail transit system plays a major role in the commercial world that they currently use diesel engine not only causing to a lot of fuel consumption but also generating numerously pollution. Therefore this project aims to study the break-even point of investment under comparison of brake specific fuel consumption and pollution of locomotive engines. By experimental works there are 3 types of locomotive engine: Pielstick M.T.U. and Caterpillar which are the difference of the combustion chamber and the fuel injection systems. The simulation load on the static tests (Dynamometer) was used following the regulation characteristic curve which is standard of State Railway of Thailand. As a result of testing the engine using common rail type of fuel injection system M.T.U. was the lowest brake specific fuel consumption at all of engine by the average of all engine speed 206 g/kW-h of brake specific fuel consumption. It is lower than Caterpillar (Semi common rail with direct injection) which is 314 g/kW-h equivalent 34.39 % while Pielstick engine a mechanism fuel injection system is 389 g/kW-h equivalent 47.04 % For pollution area there are Hydrocarbon (HC) Nitrogen Oxide (NOX) and black smut. The engine with direct injection system relieved the previous substance less than the pre-combustion engine. Moreover the compound of carbon monoxide (CO) was found that the pre-combustion engine (Pielstick) discharged carbon monoxide (CO) less than the direct injection engine (Caterpillar) whereas the common rail engine emancipated same substan cenear by with the pre-combustion engine (Pielstick). However the new technology of the engines is high maintenance costs. Therefore a number of applications have to be needed to make a quantitative value for the investment.

The purposes of this study were 1) to create a construction of design program for practical skills system of engine repairing 2) to determine the quality of design program for practical skills system of engine repairing 3) to evaluate the users’ satisfaction of a design program for practical skills system of engine repairing. The sample used in this study consisted of 30 lecturers from automotive division university and 39 lecturers from the office of vocational education commission. The tools used in this study were the quality assessment for practical skills system of engine repairing and the satisfaction assessment of the users to design program for practical skills system of engine repairing. The statistics used for data analysis were percentage mean standard deviation and t-test for dependent samples. The results of the study were as follows: 1) the quality of were very good level design program of for practical skills system of engine repairing( = 4.70 S.D. = 0.21). 2) User’s satisfaction level after accessing the program were very good level ( = 4.60 S.D. = 0.11). 3) The results were compared to assess the satisfaction level of the user from Nakhonphanom university and the office of vocational education commission towards of design program for practical skills system of engine repairing in the field of design content and application found that in each of the satisfaction level did not differ significantly at .05 level. 4) The results were compared to assess the satisfaction level of industrial community education and technical college towards of design program for practical skills system of engine repairing in the field of design content and the application found that in each of the satisfaction level did not difference at significance level .05