So you're saying that you got a 40 deg temperature drop because one supercharger had less friction than the other?
So your compressor was dumping heat into the air flow at a rate high enough to raise the temperature by 40 degs higher than the other compressor? And you're attributing the temperature rise to internal FRICTION????
I'm not saying that you didn't actually measure this temperature delta, I just think it's highly more likely that something else was causing it, such as differing air mass flow rates, a misplaced thermo-couple or different pressure deltas across the compressor. In order for the air flow to have been 40 degrees hotter in one product vs. the other (at steady state, with everything else the same) the surface temp of the actual compressor must have been MUCH higher than 40 degrees hotter than the cooler compressor, which as you correctly stated, would be pretty stinkin' hot.