Effects of Engine Cooling System on Engine Performance: Balancing Engine Power and Fuel Consumption

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Effects of Engine Cooling System on Engine Performance: Balancing Engine Power and Fuel Consumption

Hisano / Nakagawa / Nakao / Sakurai / Tanaka

During high engine load, adequate engine cooling is necessary to prevent irregularly highly machine temperatures and spark knock that are issues affecting high power from being achieved. However, excessive cooling during low engine load or cooling locations that do not require cooling relatively exacerbates fuel consumption. Therefore, optimization of the engine cooling system is needed to achieve higher performance of motorcycle engines.First of all, in water-cooled engines, conventional water cooling system adjusts the cooling amount via flow channel switching with a thermostat, which is opened in high water temperature. However, with the bypass channel, water may bypass the radiator but still continues to circulate, thereby leading to loss arising from heat transfer from the cylinders. Moreover, use of a thermostat allows water to flow through the radiator even during low engine loads under high water temperature operation, thereby resulting in further heat transfer from the cylinders. In order to solve this issue, we consider that an electromagnetic valve installed in a single path cooling circuit without bypass channel blocks water circulation and creates zero flow without depending on engine operation condition. As a result, we achieved early engine warming, loss reduction, and fuel consumption improvement.Next, with respect to the optimization of cooling distribution, we found it desirable to concentrate cooling near the spark knock spots and hot spots and to warm the cylinder block for loss reduction simultaneously. As a specific method, water inflow from the cylinder head instead of from the cylinder block can reduce knock strength.