COMBUSTION SPACE = BORE/2 X BORE/2 X 3.14 X COMBUSTION AREA DISTANCE = xxx (cubic inches)
COMBUSTION SPACE = ((.5 X .5) X 3.14) X .181 = .142 (cubic inches)

SWEPT VOLUME = BORE/2 X BORE/2 X 3.14 X STROKE = xxx (cubic inches)
SWEPT VOLUME = .5 X .5 X 3.14 X 1.25 = .981 (cubic inches)

CR = SWEPT VOLUME + COMBUSTION SPACE/COMBUSTION SPACE
CR = (.981 + .142)/.142
CR = 7.908

Another easy way of figuring volume is ((Bore x bore) x stroke) x .7854 = Volume

(I have a spread sheet that I made up years ago that does all the math for me. It has formulas for lots of mechanical problems, and all I have to do is plug in the measurements and it spits out the answer.)

AV8TOR