bow poundage is not a good measure. It does have something to do with it, but Kinetic energy is the factor most often used. Another thing to keep in mind is that not all mechanical heads work the same, or need the same amount of KE. A well tuned bow also plays a factor in how well the heads work. A good rule of thumb is 55 ft/lbs out of a well tuned bow should be able to produce good results with heads of 1 1/2" or less. Again though this is only a general rule and there are some exceptions.

TAKE YOUR KIDS HUNTING AND YOU WON'T BE HUNTING FOR YOUR KIDS