A four stroke petrol engine 80mm bore, 100mm stroke, is tested at full throttle at constant speed. The fuel supply is fixed at 0.068kg/ml and the plugs of the four cylinders are successively short circuited without change of speed, brake torque being correspondingly adjusted. The brake power measurements are the following; With all cylinders firing =12.5kw With cylinder No.1 cut off =9kw With cylinder No.2 cut off =9.15kw With cylinder No.3 cut off =9.2kw With cylinder No.4 cut off =9.1kw. Determine I.P of the engine under these conditions. Also determine the indicated thermal efficiency. Calorific value of the fuel is 44100KJ/kg. Compare this efficiency with the air standard value. Clearance volume of one cylinder is 70×103mm3 .