I can remember on our sbc that during a run the fan was off. Just the waterpump. At the shutdown the fan would be turned on. The car never got over 190 degrees on a hot day. You could be moving water too fast, but, as dumb of a question as this might be.... have you checked to see if you have a gasket issue? If you sucked an intake you are leaning your car way out and would get the temps you are seeing. Just a thought.