A unique high swirl bomb (max. swirl rate of 22,000 rev/min.) has been constructed to simulate conditions in the small direct injection Diesel engine with direct and positive control of pressure, temperature and injection rate. The bomb is equipped with 3 alternative heads as follows: a) an anemometer head for pre injection velocity surveys b) an instrumented head for heat release tests c) a photography head. In mode b) the bomb operates with a high speed data acquisition system and in mode c) with a 8000 frame per second camera. An extensive series of heat release and photogr^hy tests has been performed and the paper summarises these results.