Pilot fuel quantity and intake temperature are two important parameters controlling the combustion process in dual fuel engines. Experiments were conducted on a LPG diesel dual fuel engine at various intake temperatures and pilot quantities. Ignition delay, rate of pressure rise, combustion duration and heat release patterns have been presented at low and high loads. An increase in the concentration of the gaseous primary fuel significantly increased the ignition delay. At high outputs the combustion of the gas by flame propagation which follows the ignition process of the pilot and the entrained gas was the dominant feature. However, at low loads combustion of the pilot fuel and the gas entrained in it were only significant.. The rapid combustion of the gaseous fuel at high output conditions, particularly when the intake temperature was high, resulted in rough engine operation.