This study specially focuses to alter different parameters instead to change design of parts. So to achieve end goal, finding the optimal situation of the engine run posses sets of mean responded terms like performance responses of break thermal efficiency (B.T.E.), mechanical efficiency (M.E.), break specific fuel consumption (B.S.F.C.), and emissive responses of nitrogen oxides (NOx), carbon monoxide (CO) and Un-burnt hydrocarbons (HC). These results were taken on the single cylinder, water cooled 10 H.P diesel engine fuelled with different blending of neem biodiesl-diesel. Experiments carried out on 10 H.P. single cylinder C.I. Engine which normally used by farmers for irrigation purpose.