is provided for each piston 18 of each cylinder 16 in this regard each crank arm 30 is located in axial alignment with its respective cylinder the crank arms 30 have predetermined radial displacement from the eccentric centerline ec l ordinarily being all equal to a radial length r l wherein 2r l equals c in fig1 for example fig2 shows a modified crankshaft 28 for a four cylinder combustion engine 12 in which a first set a of crank arms is located on a first side of the modified crankshaft while a second set b of crank arms is located on a second opposite side of the modified crankshaft each crank arm 30 extends the radial length r l from the eccentric centerline ec l accordingly one aspect of the aforesaid modifications is to change the radial length of the crank arms from being centered on the original true centerline tc l to being centered on the new eccentric centerline ec l each modified crankshaft journal 32 includes an off set portion 40 the off set portion 40 has a maximum 40 39 that is equal to the off set o the maximum 40 39 of the off set portion 40 is shown located on the second side of the modified crankshaft that is on the side thereof facing toward the second set b.