In the view of unstable supply & cost of petroleum diesel, being an alternative source bio-diesel is used. Bio-diesel is an oxygenated, non-toxic, sulphur free, biodegradable,renewable and alternative fuel for petroleum diesel.In this project Evaluation of food based and non food based bio-diesel has been made for four bio-diesel blends. I have used different blends of palm, castor & karanja oils with diesel in combination of 40% & 60% those are PKB40,PKB60,PCB40,PCB60. Also analysed smoke levels at various injection pressures of 190 bar,210bar & 220bar as Fuel injection pressure plays a very important role in the combustion process of diesel engine and hence affects the engine performance. This will give important perspective on how bio-diesel blends can give performance comparable to petroleum diesel.