$8\mathrm{.}39$ A spark$-$ignition engine with a compression ratio of $8$ operates on an Otto cycle using air with a low temperature of $60F$ and a low pressure of $14\mathrm{.}7$ psia $.$ If the energy addition during combustion is $800Bt\frac{u}{l}bm,$ determine $(a)$ the work output and $($b$)$ the maximum pressure.

calculate for n effiency in $\%,$ work in ft$-$lbf$/$lbm$,$ v$2$ in lb$/f{t}^3,$ T$3$ in R$,$ p$3$ in psia