Abstract: - Fuels are one of the important research objectives now a day because its own preferences in various sectors like transportation, industrial and agricultural needs. In order to develop the additional requirement some mixed fuels known as biodiesels is an encouragement in research areas as an alternative fuel source, look on this karanja oil mixes with diesel can give good results in Indian context. In the present work experimental investigations are carried out to evaluate the performance of single cylinder, four stroke, direct injection dual fuel, variable compression ratio engine with pure diesel, Karanja biodiesel (B5, B10, B15, B20) and with enrichment of CNG through inlet manifold (like 2lpm, 4lpm, 6lpm) by varying load (25%, 50%, 75%, 100% load) and at rated speed 1500 rpm.

Initially the experiments are conducted with injection opening pressure 200 bar and at compression ratio of 16, And the experimentations are repeated by varying Injection opening pressure (at 200bar, 220bar and 240bar) and compression ratio (at 16 CR, 17 CR and 18CR) combinations. The effects of various performance, combustion and emission parameters are computed.

The Results obtained from experimental investigations are presented for comparative effects of CNG and karanja bio diesel. The blends of karanja in the diesel under standard conditions have shown distinct performances at various loads, B20 has stood best of all the other blends with the brake thermal efficiency and BSFC equal to that of pure diesel.

Keywords: Bio diesel, Karanja oil, Blends, Engine, Emissions, Brake thermal efficiency