Analysis of Engine Performance with NGV Nabila Sulaiman 1 , Sany Izan Ihsan 2 , AKM Mohiuddin 3 and Maizirwan Mel 4 Department of Mechanical Engineering, International Islamic University Malaysia ,IIUM Kuala Lumpur, Malaysia 1 jovialstar87@yahoo.com, 2 sihsan@iium.edu.my, 3 mohiuddin@iium.edu.my, 4 maizirwan@iium.edu.my ABSTRACT This paper presents experimental results carried out to evaluate brake thermal efficiency and fuel consumption by gasoline and compressed natural gas (CNG). In this experiment, a 4-cylinders gasoline engine has been modified to bi-fuel engine, then the engine is operated for the condition of fixed load condition to obtain same brake power output from both fuels and all the corresponding results such as fuel flow rate and brake thermal efficiency have been measured for evaluation. The test results show that gasoline has higher fuel consumption and brake thermal efficiency than CNG. Details results including fuel consumption and brake thermal efficiency have been discussed in this paper. 1. INTRODUCTION Natural gas vehicle (NGV) is not new in the industry; however, it is becoming an uprising issue because of its advantages compared to gasoline. The increasing number of vehicles from million of cars and light-duty trucks, almost exclusively operating on gasoline and diesel fuel, are major contributors to severe environmental problems such as global warming, haze and acid rain. The major sources of particulates (small unburned particles of hydrocarbons and sulfur) and nitrogen oxides are from diesel fuel that being used by heavy duty trucks and buses also caused emissions and these particulates have cancer-causing potential and it could cause significant respiratory problems. Alternate vehicle fuels such as natural gas have long been proposed as a way to provide significant air quality benefits over gasoline fuels. Significant advances have been made in the past few years that have highlighted the efficiency and emission potential of NGV. In transportation sector, natural gas is becoming more important because it is more environmentally friendly, safer and lower fuel cost compared to gasoline power vehicle. NGV was found to give NOx emission of about 75% less and produced approximately 35% less CO2, compared to conventional gasoline vehicles. Natural gas also has low well-to-wheel emissions, except for hydrocarbons that escape throughout the fuel chain. Lighter than air, with a high ignition temperature, it has better safety characteristics than gasoline, although a risk of explosion exists in closed spaces. In addition, in response to the high fuel prices of gasoline nowadays, it insisted the drivers to use alternative fuels like natural gas which is cheaper than gasoline. In this paper, the engine performance of NGV and gasoline has been investigated. An engine performance means how well an engine is doing its job in relation to the input energy or how effectively it provide useful energy in relation to some other comparable engines. Engine performance is a related parameter like speed, inlet pressure, temperature output and etc. The useful range is limited by various factors, like mechanical stresses, knocking, overheating etc. Due to this factor, there is a practical limit of maximum power and efficiency obtainable from an engine. The overall engine efficiency related to other efficiencies is encountered when dealing with the theory, design and operation of engines. The energy flow through the engine is expressed in three distinct terms which are indicated power (ip), frictional power (fp) and brake power (bp). Indicated power can be computed from the measurement of forces in the cylinder and brake power is computed from the measurement of forces at the crankshaft of the engine. The friction power can be estimated by motoring the engine. In this experiment, a computer control engine test bed has been used, where engine dyno can be setup with any load/speed conditions. By using this test bed, the results have been collected for evaluation. Therefore, the objective of this present experiment is to compare the fuel consumption and brake thermal efficiency between CNG and gasoline. 2. EXPERIMENTAL SETUP & PROCEDURES A proton Wira 4-cylinder engine, 8 valves engine was set up on a test bed. The engine has a bore 73 mm, stroke 63.6 mm, capacity 1597 cc and a compression ratio 10. The method by which the coil current is controlled gives the dynamometer varying types of power/speed characteristics, such as constant torque or constant speed. The engine is operated with variable load condition, starting from 3 N.m with increment of 3 until it reaches 18 N.m at each operating speed such as 2000 rpm to 4000 rpm. The airflow rate was measured with an airflow meter. The fuel system makes the engine can run both gasoline and natural gas. The gasoline consumption was measured with the fuel flow meter (load cell arrangement) and natural gas was measured with gas flow meter (pressure difference). 2.1 Equation of State