You cannot equate those figures
251cc equals 15.32 cubic inches.
40 square feet is 5760 square inches. 5760 square inches times 0.1 inch equals 576 cubic inches. Since there are 277.4196 cubic inches in a (US) gallon, 576 cubic inches is about 2.49 gallons.
This is not a valid conversion. Cubic units is a measure of volume while square units is a measure of area.
2,440 cubic inches.
883cc is 54 cubic inches.
1300cc equals 79.33 cubic inches.
1620 cubic inches
19 cubic feet equals about 32,832 cubic inches.
656.25 cubic inches is about 0.01075 cubic meters.
3,520 cubic inches equals 2.037 cubic feet.
1.831 cubic inches.
195cc equals about 12 cubic inches.