The usage of transesterified oil blends on various CI engine applications have proved successful where reduced emissions and better performance characteristics are noticed. The usage of edible oils for biodiesel production is a major disadvantage rising to food scarcity and hence the application of non edible oils has become the need of the hour. The monitoring of engine combustion characteristics is highly essential in order to understand the engine behaviour and effectiveness of the fuel powered. Adjustments of injection timing enable the improvement of performance and engine emissions. The current study evaluated the various combustion characteristics of CI engine fuelled with B10 and B20 blends of Mahua biodiesel blends which was processed from non edible Mahua oil by acid esterification followed by alkaline esterification. The experiments were carried on a single cylinder, direct injection 3.5kW CI engine running at constant speed of 1500 rpm. The combustion parameters like In cylinder pressure and heat release were evaluated at 50% engine loading because the diesel genset engines also run on part load conditions. The blends exhibited slightly increased delay period and reduced peak cylinder pressure compared to diesel. The peak heat release was also slightly less compared to diesel.