Investigating the impact of Karanja oil biodiesel and JP-8 fuel on diesel engine performance, emission and wear are very important for military track and wheeled vehicles due to their great potential as alternative fuels. In the present study, a military 585 kW CIDI engine was fuelled and tested with diesel, Karanja oil biodiesel and JP-8 respectively. The performances of fuels were evaluated in terms of brake horse power, specific fuel consumption, brake specific energy consumption, brake mean effective pressure, thermal efficiency and heat release rates. The emission of carbon monoxide (CO), unburnt hydrocarbon (UHC), and oxides of nitrogen NOx with the three fuels were also compared. Both Karanja oil, after transesterification and JP-8 exhibit the properties (density, viscosity and calorific value) within acceptable limits of ASTM standard. Performance of both JP-8 and pure Karanja oil biodiesel were slightly lower than diesel. Emissions of CO and UHC were found lower with both Karanja oil biodiesel and JP-8 as compared to diesel fuel. However, only JP-8 fuel had lower NOx emission whereas Karanja oil biodiesel had 10% higher NOx emission. The engine wear was also tested after a 100 hours run.