Air consumption for a 4-stroke SI engine is measured by means of a circular orifice of diameter 30 mm. The Cd for the orifice is 0.63 and the pressure across the orifice is 155 mm of water. The barometer reads 750 mm of Hg. Temperature of air in the room is 37oC. The piston displacement volume is 1780 cc. the compression ratio is 6.8. The fuel consumption is 8 kg/hr and having heating value of 43.6 MJ/kg. The BP developed at 2500 rpm is 28 kW. Determine, (a) volumetric efficiency, (b) air-fuel ratio, (c) brake mep, and (d) relative efficiency on the brake thermal efficiency basis.