The actual efficiency that an engine is capable of extracting the energy from a fuel due to the combustion process for useful work is known as the Combustion Efficiency or the Fuel Conversion Efficiency. The combustion efficiency can be calculated from: The energy content of several common fuels are: Fuel Energy Content, (Mj/kg) Petrol 44 Diesel 43 Natural Gas 50 Liquefied Petroleum Gas 49 Propane 46 Methanol 20 Hydrogen 120 Example The table below provides examples of the combustion efficiencies for a 3L, V6, twin turbo petrol engine at different engine speed and load sites. Engine Condition Units Part Load Maximum Torque Maximum Power Engine Speed (rpm) 1500 4000 6500 Torque (Nm) 45 550 464 Fuel Flow (kg/hr) 3 62 94 BSFC (g/kW.hr) 378 270 298 Energy Content, Qhv (Mj/kg) 44 44 44 Combustion Efficiency, ηc (%) 22% 30% 27%
