A six$-$cylinder $4-$stroke cycle petrol engine is to be designed to develop $320$ kW of $($b$.$p$)$ at $2600$ rpm$,$ the bore $/$ stroke ratio is to be $1$:$1\mathrm{.}3.$ Assuming the mechanical efficiency is $(90\%)$ and an indicated mean effective pressure of $10$ bar, determine $($a$)$ The required bore and stroke. If the compression ratio of the engine is to be $(7$:$1)$ determine $($b$)$ The consumption of petrol in kg$/$h and in kg$/$bp$.$hr$.$ Take the ratio of the indicated thermal efficiency of the engine to that of the constant volume air standard cycle as $0\mathrm{.}6$ and the calorific value of the petrol as: $44770$kJ$/$kg$.$