We completed testing of the tank today, and the result is a resounding success. Front and back temperatures on the engine have equaled out completely. Overall temperature at peak performance does not exceed 90 degrees C - textbook. One tip: - careful of modern thermostats. The cheap ones do not open on time and the expensive ones that do re rated too high. The result is that the heating cycle is unbalanced and this is not good for this kind of system. Recovery and equalization takes so long that damage cannot be ruled out. Drilling holes in the thermostat does not assist in any way. One thing that occurred to us was to put a paddle fan on the alternator as that will run air over the outside of the tank bottom. Not necessary as the tank performs so well that one might even be running a bit cool at low revs. Well done Manie!