$1.$ Two possible OHV combustion chambers are being considered. The first has two valves, and the second has four valves per cylinder. The diameter of the inlet valve is $25$ mm for the first design and $15\mathrm{.}5$ mm for the second. If the second design is adopted, calculate the percentage that the total valve perimeter is increased by$.$ If the valve lift is the same between the two designs, calculate the percentage increase in curtain flow area.

$2.$ Why does a GDI system allow for great thermal efficiencies as it relates to compression ratios?

$3.$ What is the "rule of thumb" recommendation for valve lift for a $40$ mm diameter valve?

$4.$ For tuning an intake runner, would a designer choose a long or short intake runner to maximize engine torque at a high rpm$?$

$5.$ What is a typical pressure for the fuel feeding a port fuel injector, in psi?