Temperatures were measured at several points on the liner and firedeck of an insulated 2-L single-cylinder, open-chamber, diesel engine. These temperatures were found to vary significantly with location. The results of these measurements were compared with the predictions of a three-dimensional time-varying thermostructural model incorporating a single-zone thermodynamic simulation of the gas cycle. On the basis of this comparison, values for several thermal boundary conditions required for engine design were deduced. Using these values, relatively good agreement was found between the experiment and model across the range of experimental conditions.