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Improvement of Gasoline Engine Performance By Modifying the Engine Cooling System
Published June 28, 1996 by Society of Automotive Engineers of Korea in South Korea
Event: KSAE Spring Conference
This paper is purposed on improving the characteristics of knock, emission and fuel consumption rate by optimizing the location and size of water transfer holes in cylinder head gasket without change of engine water jacket design. The cooling system was modified in the direction of reducing the metal surface temperature in the head and increasing the metal surface temperature in the block.
The optimization of water transfer holes in cylinder head gasket was obtained by "flow visualization test''''. The water transfer holes were concentrated in front side of the engine in order to reduce thermal boundary layer in the water jacket of No. 2 and No. 3 combustion chamber in the cylinder head, which would have a large knock intensity, and increase thermal boundary layer in the water jacket of the cylinder block.
When the modified coolant flow pattern was applied as mentioned in this paper, the knock characteristic was improved. The spark timing was advanced up to 2° in low and middle speed range at a full load. Also, HC emission at MBT was reduced by 5.2% , and the fuel consumption rate was decreased up to 1% in the driving condition of 2400 rpm and 250 kpa. However, since this coolant flow pattern mentioned in this paper might deteriorate the performance of vehicle cooling system due to the coolant flow rate reduction, a properly optimized point should be obtained.