The diesel engine has for many decades now assumed a leading role in both the medium and medium-large transport sector due to their high efficiency and ability to produce high torque at low RPM. Furthermore, energy diversification and petroleum independence are also required by each country. In response to this, biodiesel is being considered as a promising solution due to its high calorific value and lubricity conventional petroleum diesel. However, commercial use of biodiesel has been limited because of some drawbacks including corrosivity, instability of fuel properties, higher viscosity, etc. Biodiesel are known for lower CO, HC and PM emissions. But, on the flip side they produce higher NOx emissions. The addition of alcohol to biodiesel diesel blend can help in reducing high NOx produced by the biodiesel while improving some physical fuel properties. In the present study karanja oil is used for production of biodiesel i.e Karanja oil methyl ester (KOME) while ethanol, isopropanol and isobutanol are the alcohols being used. The blends are prepared by volume with 70% of fossil diesel, 20% of KOME and 10 % of respective alcohol. Engine performance such as Brake thermal efficiency, Brake specific fuel consumption and exhaust emission characteristics such as NOx, CO, HC and smoke opacity were evaluated at two different compression ratios from no load to 20% increment till the full load. The aim is to find the most optimum alcohol to be blended with a viable compression ratio to match up to the performance standards of fossil diesel while an improvement on the tightening emission norms and superior physical fuel characteristics. The results are promising for profitable use of biodiesel with addition of alcohol and to supplement a part of the increasing energy demand.