Engine Displacement: 

The engine displacement is the number of

cubic inches (cu. in.) the piston displaces
when it moves from bottom
dead center to top dead center. 

To calculate displacement, calculate the Area of the piston face; multiply that
by the Stroke, then by the Number of cylinders. 
Example: (D=A x S x N) 11.800 x 3.750 x 8 = 354 cu. in.