PENGARUH RASIO KOMPRESI TERHADAP EMISI GAS BUANG CO DAN HC DENGAN BAHAN BAKAR LIQUEFIED PETROLEUM GAS PADA SEPEDA MOTOR YAMAHA JUPITER Z 110 CC

Abstract

The objective of this research are: (1) To investigate the effects of compression ratio to CO and HC emissions of exhaust gas by using liquefied petroleum gas as fuel on Yamaha Jupiter Z 110 cc motorcycle. (2) To investigate the lowest amount of CO and HC emissions of exhaust gas on Yamaha jupiter Z 110 cc motorcycle using liquefied petroleum gas as fuel after varying its compression ratio. The method used in this research was an experimental method. The research was conducted at the Laboratory of Automotive Mechanical Engineering Education Program JPTK FKIP UNS located at Ahmad Yani street no. 200 Kartasura, Surakarta phone (0271)718419 Fax. (0271)729928. The tools used to measure the amount of CO and HC emission of exhaust gas was gas analyzer type 898 OTC Stargas Global Diagnostic. The population in this research was a Yamaha Jupiter Z 110 cc motorcycle and the sample of this research was a Yamaha Jupiter Z 110 cc motorcycle with 2P2675042 engine number that used the conversion sets such as a modified carburetor and liquefied petroleum gas as fuel. The amount of CO and HC emission of exhaust gas measurement based on SNI 09-7118.3-2005 test method which organized the measurement of L category  vehicle on idle condition. The data analysis technique used in this research was descriptive investigation method. The descriptive investigation method used was comparative study. The data were obtained from the measurement result documentation of the exhaust gas emission of CO and HC by applied three different compression ratio that were 8.6 : 1 (low), 9.3 : 1 (standart) and 10 : 1 (high). Based on the result of this research, it can be concluded that: (1) The higher compression ratio of the engine caused the higher combustion chamber pressure and temperature at the end of compression stroke. The characteristic of liquefied petroleum gas that have high octane rating about 110 RON and lower flammability limit about 460˚C need the high pressure and temperature before finally burned at the moment when ignition timing started. So that the high compression ratio will caused more effective combustion processes on the engine that used liquefied petroleum gas as fuel. (2) The amount of CO emission of exhaust gas produced on Yamaha Jupiter Z 110 cc motorcycle by using liquefied petroleum gas as fuel at 8.6 : 1 (low) compression ratio was 0.135 %, at 9.3 : 1 (standart) compression ratio was 0.037 % and at 10 : 1 (high) compression ratio was 0.026 %. Then the amount of HC emission of exhaust gas produced on Yamaha Jupiter Z 110 cc motorcycle by using liquefied petroleum gas as fuel at 8.6 : 1 (low) compression ratio was 1533 ppm, at 9.3 : 1 (standart) compression ratio was 1270 ppm and at 10 : 1 (high) compression ratio was 820 ppm. The measurement result data showed that the lowest amount of CO and HC emission of exhaust gas produced on Yamaha Jupiter Z 110 cc motorcycle by using liquefied petroleum gas as fuel was at 10 : 1 (high) compression ratio that was 0.026 % for CO and 820 ppm for HC.