Q$5.$ The following data relates to a four$-$stroke CI engine operating at the sea level conditions of $1\mathrm{.}013$ bar and $10C$:$bp=275kW,$ speed $=1800rpm,$ air $\frac{?}{?}$ fuel ratio $=20$:$1,bsfc=0\mathrm{.}24k\frac{g}{k}Wh,$ Vol$\_$Effy $=80\%.$ The engine is fitted with a mechanical supercharger so that it may be operated at an altitude where the atmospheric pressure is $0\mathrm{.}75$ bar. The power consumed by the supercharger is $9\%$ of the total power produced by the engine, and the temperature of the air leaving the supercharger is $30$ degC. Assume that the air$/$fuel ratio and the volumetric efficiency remain the same. Calculate the following: $($a$)$ Engine capacity and bmep of the unsupercharged engine. $($b$)$ Increase in air pressure required in the supercharger to maintain the same net output of $275$ kW $.$

$($Ans: $($a$)$ Vd$,$e $=0\mathrm{.}024495m3,$ bmep $=7\mathrm{.}48$ bar, $($b$)0\mathrm{.}442$ bar$)$