There are many application areas, where the ability to accurately predict the speed of expansion of fragments from explosively disseminated porous shells is important. For inert materials this speed in part determines the size of the resulting cloud. For reactive materials this speed in part determines the ability to ignite the material and determines the trade-off between reactive and inertial fragment effects. Gurney analysis has been used extensively for many years to approximate the speed of fragmenting solid material shells. This work investigates the behavior of HE driven porous shells in spherical and cylindrical geometry and identifies factors to use to multiply solid shell Gurney velocity by to predict the speed of a porous shell.