[TR] Fan Hookup

[Jim Muller]

On 11 Nov 2007 at 21:24, DLylis at aol.com wrote:

> I ain't no scientist, but when a temperature gradient is set
> up does the coolant not do it's level best to become all the
> same temperature?

Well, yes, but it's a question of how fast.  And what other things 
are going on.

The only physical connections between coolant in the radiator and the 
coolant in the block are the narrow diameter radiator hoses.  When 
the engine is running the heat transfer due to water convection is 
very much greater than the heat flow through the water itself, which 
is how it keeps the block cool at all.  Meanwhile, air convection 
happens within the engine compartment.   This carries heat away from 
the block so that eventually it will cool down by itself.  Depending 
on various engineering values (i.e. specific features of each car) 
rather than science per se, either of these phenomena could be 
faster.  Certainly keeping the fan on could help air flow around the 
block if the air can't convect by itself.  But neither of these 
phenomena is fast compared to the water flow when the engine is 
running.  Yes, keeping the fan on would cool things down a little 
faster, but only just a little and nothing under a Triumph bonnet 
would benefit from it.

-- 
Jim Muller
jimmuller at rcn.com
'80 Spitfire, '70 GT6+



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