Mechanical fans sap engine horsepower. Electrical fans basically don't
(except for the much more efficiently produced electrical power coming from
the alternator).
A cooling fan is needed only at low car speeds (when insufficient air flow
is passing through the radiator). If you drove your car at highway speeds
all the time, you could probably totally eliminate the cooling fan. This is
why most modern cars now have (or will have) electric fans, if they have one
at all. This is also why the electric fan is thermostatically controlled so
it comes on only when needed which usually will be at low/no forward car
speed and if additional heat load (i.e., air conditioning or hot ambient
temperature) exists. You will also note that electric fans are getting
smaller and smaller. Again, this is because they are hardly needed. Car
design engineers are also decreasing the "open grill area" on the front of
cars (to reduce air drag) and using approaches to "duct" air flow to the
radiator in a way that increases air flow and cooling efficiency. There are
liquid cooled engines in development that don't even use a radiator (so no
fan will be needed). Of course, you could buy a Volkswagen Beetle (no
radiator, no fan, no coolant).
Now a true story: Years ago, I owned a '73 Datsun 240Z. If you are
unfamiliar, it had a 2393 cc straight 6 cylinder engine. I was driving on
the interstate from Mobile, AL to Pascagoula, MS when the fan & alternator
belt broke. It was around 9 pm on a Sunday night so everything was closed.
It happened to be around 35 degrees Fahrenheit. Since I had to get home in
order to go to work the next day, and had no other means to travel, I
decided to proceed without the belt. I drove about 40-50 miles doing the
following:
speed up to about 80 mph (keeping a wary eye out for cops) and drove until
the temp gauge started to approach the "hot" mark then coasted to a stop,
idled a minute or two, then shut down the engine to wait for the temp gauge
reading to reduce to some low value. I repeated this several times until
arriving home about 2 hours later. When I reached home, I checked under the
hood and found that not only was I overly conservative, but I could even
open the radiator cap without it even boiling out coolant!!! It seems the
car had such excellent cooling that not having the fan had not even
perturbed it. HOWEVER, the problem I did have was that I was running down
the battery by having to run the lights (no belt = no alternator = no
battery charging). Fortunately, when I realized this after 1 or 2 cycles
(didn't occur to me at first!!) I also minimized headlight on-time and used
the coast down to "pop the clutch" for restarting the engine.
I wouldn't recommend this, but it worked for me in an emergency.
Roy
'60 TR3a TS63103LO (in restoration)
techman@metrolink.net
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