Magnum cooling

I suspect you are having an airflow issue. Looking at the shroud for those electric fans, I think you are losing efficiency because it is not pulling much air from a large portion of the radiator in the corners, since the shroud is very thin.

Is the shroud sealed to the radiator with foam or rubber? Maybe it is leaking around the edges, losing efficiency?

I am hoping to try a clutch fan if I ever get my junk together. The full size truck fan clutch takes up a lot of space, but there are Dakota and Durango fan clutches that appear to be thinner when I see them in junk yards. Hoping to go that route on mine and then run a shroud that is more conventional and doesn't restrict the corner sections of the radiator as much.