Diesel engine with alternate fuel ( a combination of Coconut Biodiesel and Triacetin additive) has been tested and the additive percentage has been fixed on the basis of better performance.Engine performance is studied with combustion pressure monitoring and with derived heat release rate calculations. Exhaust gas analysis has been taken up and several component reductions have been observed. After investigating the cylinder vibration in both FFT and time wave plots, 10% triacetin blend is concluded as befitting blend which does not create undue detonation or knock which may ultimately reduce the reliability of the engine.