Transient heat flux measurements were obtained at four positions on the cylinder head of a four-stroke single-cylinder spark-ignition engine. Tests were performed for both fired and motored operation of the engine. The primary engine operational variable was engine speed. The results showed that the heat flux varies considerably with position of measurement. At fired conditions, the initial high rate of increase of heat flux at each position of measurement correlated with the calculated time of arrival of the flame at that position. Finally, as expected, the peak heat flux was found to increase with increased engine speed.