Originally Posted by ZraHamilton
In theory, could a filter media with wire backing (fram ultra, wix xp) be strong enough without a center tube at all? It would need metal end caps for the media/wire to be glued into with a resin. Without a center tube, there would be less flow restriction.
If the wire backing was strong enough to do the job without a center tube, then it would have to be just as stiff structurally as a center tube. Center tubes don't cause much delta-p compared to the media ... unless of course the center tube has louvers and they are barely opened up to a fine slit. That can happen, so always inspect louver formation if buying filters that use a louvered center tube.