[Fot] Aluminum Radiators

[TeriAnn J. Wakeman]

On 1/5/22 2:50 AM, Philip Gott wrote:
> 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….
> Never went anywhere to my knowledge.
> Phil Gott

Never went anywhere probably due to overheating 😁 😁 😉

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.


TeriAnn

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