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Evaluation of the combustion process in a wall-wetting direct-injection diesel was accomplished by calculation of the apparent rate of heat release from the measured pressure history for several engine speeds, loads, and start-of-combustion timings. At most of the conditions tested, the combustion process seemed to be characterized by transitions from premixed burning to airborne-diffusion burning, and finally to wall-type diffusion burning. Advancing the timing increased the amounts of premixed and airborne-diffusion burning relative to wall burning. The premixed portion of the burn also increased as the engine speed was increased. The results of this study suggest that the diffusion burn in this engine progresses from being mostly airborne at the lightest load to being mostly from the wall at the heaviest load.