What Ed has called 'thermo-siphon' cooling is still used in some
applications (mostly very heavy industrial engines), but called
'ebullient cooling' in more modern parlance. Water jackets are designed
so that small bubbles generated by nucleate boiling on the water jacket
side of the very hottest parts of the cylinder head can rise through a
vertical path (with no traps) though the water jacket and from thence
through the upper hose and into the top tank of the radiator.
I have a '57 IH Farmall Cub 'Lo-Boy' tractor (a tiny little thing) which
has a 60 cubic inch (1 liter) all iron I-4 flathead engine--which uses
ebullient cooling. Factory rated at all of 13 HP !!!
Vertical flow radiators are definitely an artifact of the thermo-siphon
(or ebullient) cooling era !! It's really kind of surprising to see how
long it took auto manufacturers to figure out that a water pump is FAR
less likely to cavitate when a cross-flow radiator is used !! This is
true 1. because the free surface of the water in the 'suction side' tank
is located above the water pump and 2. because very little flow
restriction exists between said free surface and the pump rotor.
Greg
Ed Solstad wrote:
Tess-
Most cars from the 30's were water cooled with a few, mostly European,
being air cooled.
The overwhelming majority of water cooled cars used thermostats
coupled with a water pump whereas a few relied on "thermo siphon"
which incorporated large diameter hoses without benefit of a pump. The
water would heat up in the engine and then rise up through the upper
radiator hoe to the top tank of the radiator where it would cool of
and sink to the lower tank to began the process all over.
The primary way of burning yourself would be to take the radiator cap
off of an overheated cooling system and rapidly pour in cold water.
The cold water hit the hot block and make like a geyser as the hot
water and steam came shooting out of the open radiator top tank. You
hopefully didn't get scalded and soon learned that you had best pour
the water in very slowly while at the same time keeping as much of
your body as possible out of the line of fire of possible eruptions.
I have a degree of personal experience having resurrected my
grandfather's thermo siphon cooled 1922 Maxwell touring car and
driving it when I was in high school in the late'50's.
Regards,
Ed Solstad
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