> But too big a pump (too large a GPM rating) doesn't leave the water
> and air in
> contact with each other long enough and reduces efficiency.
Nope, that's a myth. A common and time-revered one, but a myth none the less.
The reason some engines overheat without thermostats is because the pressure cap
is on the high pressure side of the radiator. Without the thermostat to limit
flow/pressure to the radiator, the dynamic pressure blows water out the cap.
Then the engine overheats due to lack of water.
> Too
> much flow from the water pump can also lead to trouble if the rest of the
> system cannot accommodate it.
That part is true, except that the problem is too much pressure, not too much
flow (see above). And after all I was talking about the design phase, so
presumably all the components would be designed to work together.
BTW, the racers up the WP flow/pressure even more, to help cool their
substantially higher output engines.
> A limiting factor is the surface area of the radiator and its inherent
> efficiency.
Agreed, that's part of my point.
> While the brass tubes are wonderful conductors of heat,
"Wonderful" perhaps, but by no means ideal. Aluminum is much better, almost
half the thermal resistance.
> (of note,
> the remaining TR3S in LeManns ran with no ill effect with its radiator fan
> removed after fan blade failures in the first two TR3S vehicles;
I've likewise driven for months at a time with no radiator fan on my TR3A ...
just have to remember to shut the engine down at traffic lights.
> The fiberboard radiator duct [MOSS 855-125 (TR3), 855-130
> (TR4)] is an inexpensive and must-have item
True, but it was only fitted to later TR3A by the factory. TR3 and early TR3A
did not have it originally.
> That would certainly be cheaper and more efficient
Guess that would depend on how you define efficiency. To me, a fan that only
consumes power when it's needed for cooling is bound to be more efficient than
one that consumes power all the time.
> than an electric pusher fan
Mine's mounted as a puller, to avoid disturbing the airflow in front of the
radiator.
> I like the idea of inserting a pipe plug into the water pump bypass line and
> drilling it to allow a reduced volume of water through the by-pass
Go right ahead, it probably won't hurt anything. Assuming of course that you
believe the original engineer made a mistake when he sized the bypass line ...
But I was quite happy with the setup on my late TR3A (recored radiator, no crank
hole, 7 psi cap, non-sleeved thermostat, Hayden electric puller fan, open
bypass) and will be moving it over to my "new" TR3 when the time comes. Only
change I plan to make is adding braces for the radiator header tank. Otherwise
they seem to crack every 10 years or so for me. Mebbe I should slow down for
the bumps instead ... Nah !
Randall
59 TR3A TS39781LO (now totaled :(
56 TR3 TS13571L next project
71 Stag LE1473L daily driver wanna be
63 Sports 6 HB7826LCV rustoration project (for sale)
57 TR3 TS21731L rusting quietly 2000 miles away
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