In this research biodiesel is produced from Xanthium strumarium L. seed oil commonly known as cocklebur, linoleic acid is also separated from same. These are used to make an attempt to enhance Calorific value of Karanja oil biodiesel fuel. Cocklebur biodiesel is also blended with diesel to find suitability with machine hardware and to find best input variables, also an attempt is made to reduce NOx emissions using EGR and retarded injection. It is found during this research that there is increase in Calorific value of Karanja oil biodiesel by addition of Cocklebur biodiesel as well as Linoleic acid, but rise in HCV is more due to addition of Cocklebur biodiesel than linoleic acid. It is also noticed that increase in BTE of Karanja oil biodiesel is more due to addition of Cocklebur biodiesel than linoleic acid in same amount under best engine operating conditions. It was noticed that there is decrease in fuel consumption as compared to Karanja oil biodiesel for same power output. It was observed that adding Cocklebur biodiesel lowers the emissions of NOx from diesel engines as compared with diesel as well as Karanja biodiesel without affecting the engine performance.