A spark-ignition engine, designed to run on octane (C8H18) fuel, is operated on methane (CH4). Estimate the ratio of the power output of the engine with methane fuel to that with octane. In both cases the fuel-air ratio is stoichiometric, the mixture is supplied to the engine at the same conditions, the engine runs at the same speed, and has the same volumetric and thermal efficiencies. The heating value of methane is 50150 kJ/kg while that of octane is 44880 kJ/kg.