EFEK DIMENSI VALVE GAP PADA KINERJA MESIN DAN BUANGAN EMISI GAS DARI MESIN PENGAPIAN EMPAT TAK: STUDI PERCOBAAN

Abstract

Valve is an important part in internal combustion engine. Care must be taken to the valve mechanism in order to keep its ideal gap dimension. The gap dimension can alter because of wearing process and loosen of adjustment screw. Gap dimension indicates the amount of air-fuel mixture entering the combustion chamber and leak of compression pressure. The leakage caused by delay time in closing the exhaust valve. This research work shows that valve gap dimension has significant effect on the engine performance and exhaust gas emission. Laboratory experiment has been performed to establish the engine performance and exhaust gas emission. The engine has been tested is 4K type of four stroke spark ignition engine, with couple intake-exhaust gap dimension varies : 10mm-20mm, 15mm-25mm, 20mm-30mm, 25mm-35mm and 30mm-40mm. The result shows that optimum engine operation is 3000 rpm with couple intake-exhaust gap dimension 25mm-35mm. In that condition engine produces BHP = 49,40 hp, BTorsi = 11,80 kg-m, BMEP = 11,49 kgf/cm², BSFC = 0,26 kg/ hp- hour and BTE = 24,29 % according to the exhaust gases emission CO = 3,6 % vol., CO₂ = 13,1 % vol., HC = 225 ppm, and O₂ = 1,1 %.