I started with smaller setups, and still have a few running next to the big one. Readings on those:
Engine: 66.44 V, 50.00 A, 3321.97 W
Conduit: 24.751768
Ratio: ~7.45 MJ/t/kW (~7.84 if you adjust for the 5% loss from the conduit)
Engine: 64.02 V, 32.00 A, 2048.53 W
Conduit: 15.142484
Ratio: ~7.39 (~7.78)
Engine: 61.41 V, 12.00 A, 736.95 W
Conduit: 5.214881
Ratio: ~7.07 (~7.45)
(The big one gives a ratio of ~7.47 (~7.86))
Like I said, I've been getting consistent results all the way up to 20 kW.
Edit: the issue seems to be using the multimeter on conduits? I tried hooking up 6 pulverizers to the setup that the multimeter said was getting 24.75/t average. Each conduit attached to a pulverizer reported an average distribution just over 4/t, but they weren't getting enough energy to run continuously, even at minimum speed (which would be 1/t). So it looks like the multimeter is reporting values that are too high by a factor of 8 when used on conduits outputting energy, I guess.