Best way i can think to discribe is.... its a gift from the gods!!!
I had my hand forced on thursday when for the second time in a month the water pump housing just cracked at the bottom this time and it was a N1 as well. So if it lasts longer than one track session i am quids in with my run with alloy water pumps. Brought the only possible soluiton ( electric as no other options here) even with having to repair the broken alloy housing. Thank the gods that i brought some alumimium solder, man does that stuff rock :-). We had to use the housing without the impeller so we removed the shaft and soldered a blanking plate over the end where we cut the bearing out of the housing. Covered the whole thing with a resin to made sure and connected the pump up which was about an hours work including the wiring.
Any way first run was not good, car got real hot in about 2 minutes then read instructions tell us to remove the thermostat. Got 3rd degree burns removing the little sucker.....fixed! car temp on long track runs was down from 96 with the N1 to 92 even with a 4 degree hot ambient temp on the day ( 42 ). No fan even but was very careful woth that though and would suggest a small thermofan to deal with that side of slow movement or traffic.
I brought the 110 litre/min unit it has its own small fan to keep it cool.
Disco i can follow your thoughts on the alt failing but that still leaves the battery to run the pump . If the belt was to break driving the alt would be the same. Where as if the belt driving the the alt and the water pump was to break, would result in no pump at all and the alt light you can help but notice when the belt or water pump housing breaks in two as i have found out twice now.
It not quite a plastic either its more like a fibre glass type material, you can see the fibre inforcment in the material. Any way it worked for me, very happy