ooo man sorry i dont research my d-series stuff. but if you had any idea what i was talking about then you would realize i said the D16A1 or 3, 9.5:1 or ZC, 9.6:1(not the D16z6)...which is a DOHC dseries motors....and even if the stroke might be shorter by 3mm, and rev slower. But they defs are stronger than the D15b, and the D16z6 garbage motors. just my .02, and if you want you can take your precious time and come back w/ better research that defeats mine, b/c i have much better things to do w/ my life.