The exhaust gas from a two-stroke cycle compression-ignition engine is exhausted at an elevated pressure into a large chamber. The gas from the chamber is subsequently expanded in a turbine. If the mean temperature in the chamber is \(811 \mathrm{~K}\) and the pressure ratio of expansion in the turbine is 4:1, calculate the isentropic enthalpy drop in the turbine per unit mass of gas.

\([256.68 \mathrm{~kJ} / \mathrm{kg}]\)