On Saturday 22 October 2005 09:06 pm, Randall wrote:
> Looking at it from an engineer's point of view, the thermal parameters
> of the radiator are extremely constrained by space and cost, while using a
> bigger water pump is cheap and easy. It just makes sense to run an bigger
> pump if that will let you get away with a smaller radiator.
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. Time is also an
important consideration because all heat transfer takes place over time. To
much flow from the water pump can also lead to trouble if the rest of the
system cannot accommodate it.
A limiting factor is the surface area of the radiator and its inherent
efficiency. While the brass tubes are wonderful conductors of heat, the lead
solder is not, nor is the loss of the central tubes to accommodate the
starting hand crank that nobody uses. A furnace-brazed aluminum radiator with
small tubes and thin vanes (similar to the core used in the Corvette) would
be ideal, if expensive. Thicker is not usually better for radiators, and oil
and transmission coolers are better located away from the radiator instead of
in front of it (or hidden in the tank as in many modern radiators).
The "pump" can also be be the one that moves air across the radiator. At slow
roads speeds or at rest, this would be the fan, and at higher road speeds,
the forward motion of the vehicle moves air through the radiator (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; it suffered
an unrelated oil pump failure) and the design of the front apron is important
at those speeds. The fiberboard radiator duct [MOSS 855-125 (TR3), 855-130
(TR4)] is an inexpensive and must-have item and might be better fabricated
from aluminum or PVC sheet for durability if not authenticity.
It also surprises me that no one has mentioned constructing a radiator fan
shroud. That would certainly be cheaper and more efficient than an electric
pusher fan and, again, aluminum or PVC sheet - the latter easily heat-shaped
around a box form - would work well.
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 in
addition to installing the factory-supplied fiberboard radiator duct. A
shroud on the back of a non-crank hole radiator sounds like a good idea as
well if you don't strive for "authenticity".
--
Hoyt
1954 TR2 TS561L
1959 TR3A TS33111L
1960 TR3A T543923L (note DMV error)
1960 TR3A TS74076L
1961 TR3A TS63304L
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