COOLING SHROUD
by Ben Prince
My wife and I lived in a very warm climate for a number of years. In these conditions where summertime temperatures
routinely exceeded 100 degrees Fahrenheit, our TF did not fare
well. The worst over-heating situation occurred in heavy stop-
and-go traffic when the engine was subjected to prolonged
idling.
To cope with this harsh environment, a number of
modifications were made to the cooling system in our TF. The
aggregate effect of these changes resulted in significant
improvement.
Perhaps the most interesting of the cooling improvements was
the installation of a shroud. It is merely a cylinder that
surrounds the fan, creating a "ducted-fan".
The flow of air to a fan tends to follow the path of least
resistance. Without a shroud, some portion of air will be
drawn from around the tips of the fan blades in the engine
compartment, bypassing the radiator. With a shroud, the blade
tips are blocked from extraneous air, forcing the cooling air to
pass through the radiator to the fan.
The cylindrical shroud that I made is approximately 1/4 inch
thick and 2-3/8 inches in depth. It has a slight taper, the
inside diameter measuring 12-7/8 inches for the edge that is
in contact with the radiator, and 13-3/8 inches on the engine-
side face. (Please see the center photographs.) The depth was
set at 2-3/8 inches because anything larger could not be
installed in our TF without removing the radiator.
The shroud was made from the rim of a heavy duty plastic
container that normally holds potted plants. The container
label identifies it as a "nurturing planter" made by Bemis, but
other brands should work. The plastic appears to be
polypropolene, but I am not certain. The planter was purchased
from a discount hardware/garden store for about $10 US.
A relatively fine tooth saw was used to cut the rim from the
planter to form the shroud. Because of radiator
protrusions, the shroud was notched on one edge to achieve a
proper fit.
The shroud is held in place with four springs. One end of
each spring hooks over the lip of the shroud, and the other end
connects to the radiator frame. It was necessary to bore a
couple of 1/8 inch holes in the radiator frame for spring attach
points. (I drilled cautiously, assuring that radiator tubes
were not penetrated.)
Before installing the shroud, I wanted to make certain that
the plastic would not melt or distort when subjected to heat. I
removed a piece of the plastic from an unused portion of the
planter, and much to my wife's chagrin, the sample was placed in
her kitchen oven. No distortion occurred until the temperature
reached 300 degrees Fahrenheit -- a temperature well above that
of a radiator. The experiment verified that shroud distortion
or melting would not be a problem.
The shroud fits very nicely on our TF. I not tried,
however, to install one in any other vehicle. I have no idea if
it will work with other T-series cars, or even with other TFs.
It will be interesting to learn what other owners encounter and
what adaptations they make.
