The account for forging variations, the NHRA allows for an additional .015-inch of stroke length. Not surprisingly, many racers now offset grind the Compstar LS7 cranks to 4.013- to 4.015 inches to gain an additional 1.3- to 1.5 cubic inches of displacement, depending on bore diameter. With a 4.185 bore and a 4.015-inch stroke, the SAM Tech’s COPO LS7 checks in at 441 cubic inches.