Its a water turbine paddle wheel. the bike back wheel sits on the rollers and up against the car wheel, the bike spins the car wheel, which , when water is applied to the turbine house, applies a force on the 1 meter long arm , which presses down on the load cell, which displays kilos on the digital scales. so this kilos reading is multiplied by the engine revs and gives a figure.
for example 11.5 kilos x 7000 rpm:- i dont bother about the three zeroes, so 11.5 x 7 = 80.5
if i tweak something and it becomes 11.6 kilos, or 7050 rpm , then it is on the correct path of adjustment.
calculations or fiddle figures arent necessary for seeing if the power increases or decreases when adjusting fuel or timing - i am happy if i see the scales or revs increasing when i adjust something.
I have just put together a logger which can be plugged into the computer, but otherwise its just as easy to use a video camera sighted on the scales and revcounter if some logging is desired.
the water doesnt cost so much, and can even be returned to a header tank if i had one. Mind you , it will boil after prolonged running as heat is generated.
I can also bolt on a seperate engine and run with a chain to the sprocket if i wish to bolt it onto the turbine shaft. at the moment the sprocket is just hanging so i dont get tangled up in it.