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<div class="moz-cite-prefix">On 1/5/22 2:50 AM, Philip Gott wrote:<br>
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cite="mid:2A9D9BC4-3F34-4B01-97F0-1144AAE6E553@aol.com">
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For a while, one of the chemical companies was advocating plastic
radiators. They even had some on display at an SAE conference.
Apparently they tested well. Their argument was that the
important factor was the net water to air heat transfer, and that
the limiting things were the water to radiator material and then
the radiator material to air, not the radiator material itself, as
I recall. They said they could mold a radiator into unusual shapes
that would enable better vehicle aerodynamics with more design
freedom in the front end….
<div>Never went anywhere to my knowledge.</div>
<div>Phil Gott<br>
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<p>Never went anywhere probably due to overheating 😁 😁 😉</p>
<p>But I agree the limiting factor is the engine cast iron to
coolant boundary because of the very low thermal conductivity of
cast iron. That's why engines are designed with coolant passages
everyplace they could make a passage. Why Chevy made 6 cyl
cylinder heads with narrower cylinder head water passages to
reduce coolant flow in the 1970s (so the engine would run hotter
to achieve SMOG numbers), And why the TR2-4 engines have a coolant
bypass coupled with skirted thermostats. In Triumph's case the
bypass was to insure some limited coolant flow during engine
warmup. If you completely block the bypass and the coolant is not
flowing you often get localized coolant boiling hot sports in the
cylinder head during engine warmup. This quickly raises the
temperature at the hot spots causing uneven thermal expansion of
the cylinder head, increasing the likelihood of cracks being
formed in the cylinder head. Warmup is a critical time for
cylinder heads because of uneven thermal expansion. Most if not
all radiator anti freeze liquids have chemicals that try to
increase coolant to metal surface adhesion. Add in chemicals like
water wetter attempt to provide better surface adhesion between
the cast iron and coolant in order to minimize localized hot
sports. But they don't help when someone blocks off coolant flow
during warmup in an effort to try and maximize coolant flow after
an engine is warmed up.</p>
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<p>TeriAnn</p>
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