there sure are lots of speculation and dreaming here, that is for sure.
a brush motor and a generator are one in the same, cept the brush timing
is set to optimize one or the other , on some air craft, they are both in one.
a starter and a generator , same unit ,with special dual brush arrangement.\
(or similar trick)
your fan clutch test method
SHOULD never be repeated , a bad idea if ever there was. Why do that?. wow.!
The FSM of each car explains how to do it with out taking any risk.
this one does well.
Saturday Mechanic - Fan Clutch Replacement - Popular Mechanics
with hand move fan ,
engine off ,cold, the fan must fell like a knife in natural room temp. butter. if it feels seized to the pump , it is.
NOW start the motor , cold.
and then strobe light (a tool) the fan hub and then the pump pulley.
note the huge diffr in rpm at idle and 2000 rpm. a the 2 points. That is the slip.
next ,follow the above link for the hot test.
most ppl that report huge MPG , gains.
are:
1: dont know how to do it. ( maybe 10000 posts here like that)
2: or the fan hub was bad, why on earth compare something good to something new and good.
google #1 and find out how to do it accurately, it's NOT easy.
averaging , is one way.
same driver, same road, same weather, same every thing.
in science this is called holding the constants and changing only one variable.
control the variables or its all just for fun and is useless.
one more link
Fan Clutch Testing: How To Test A Cooling Fan Clutch | Suite101.com
ok some fan clutches have a spring trap. (opens and closes at a specific heat thru rad) [ bi-metal spring is only one type ]
other fan clutches have a thick Silicone grease inside that gets hard when hot (feels like butter at room temp)
buy a strobe light- tachometer and strobe your fan and learn what it really does. It slips like crazy when cold and then trips on , on hot days , at a red light.
YMMV. really. testing MPG below 2-3mpg is no simple matter.
in fact this is the natural background error, in the best of conditions.
reporting gains inside this range, requires publishing your study and proving all variables were controlled.
as each car has differences and conditions of repair.
if you don't understand it? , take it apart and behold, see what it really is.
But, I still like a flex fan. with the nice curved blades.
I hope my directions and ideas are well received.
All my life , I've fought to kill measurement errors.
otherwise, it's all for nothing.