A lot depends on how much " juice" your turning loose!

Spitfires may require a little more kinetic energy to push through a deer than say a Snyper or a Steel head, so to be on the safe side you want to know what your set up is generating in kinetic energy.

Most feel a person needs a minimum of 50-55 foot pounds of KE to get positive consistent results on whitetails using a mechanical. Depending on the cut, and the style of the head even these numbers could be lacking in my opinion. There are other varibles, but that gives you an idea of what you want to look at.