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was the reason why the after cooler was designed to cool the air and cooling the air increases the density of the gas. Therefore we can say that the engines with after-cooler installed with it tend to have higher output than the engines without after-cooler. After-coolers do have pathways for water from the radiator. This water does the heat transfer thereby cooling the air that goes into the combustion chamber. It is not only about cooling the air that goes into the combustion chamber that it does, it increases the density of the air thereby increasing the power output.