`1.0` gallon pure octane `( "density" 2.65 kg//"gallon")` on combustion prodeces `11.53 kg CO,CO_(2)` and `H_(2)O.CO` is formed partially due to combustion of octane which is responsible to decrease the efficiency of engine. If complete combustion of octane to `CO_(2)` and `H_(2)O` provide `100%` efficiency to engine, calculate efficiency of engine in the above case.