A Study of Fuel Economy and Exhaust Emission according to Engine Coolant and Oil Temperature

Abstract

As oil prices increase and regulations on emissions are tightened, demands for improved engine performance such as fuel economy and exhaust emission have increased accordingly. Therefore, various new technologies have been developed to meet such demands. Among them, cooling system is spotlighted because it has great effect on fuel economy, but there has been little work on cooling systems. In this study, we measured friction losses of engine parts according to engine oil temperature (using the strip-down method) and also obtained optimized oil temperature which has the minimum friction losses. In additions, we analyzed the correlation between engine oil temperature and coolant temperature. Based on these results, we determine the optimal range of engine oil temperature and investigate the effect of engine speed and indicated mean effective pressure on fuel consumption and exhaust emission characteristics. Finally, we found that although the fuel consumption was improved in the selected oil temperature range, the characteristics of exhaust emission were not improved under the conditions.