[Fot] TR2/3/4 engine cooling

[Michael Porter]

On 5/12/2019 7:15 PM, Peter Vucinic via Fot wrote:
>
> Hi John,
>
> Went through that many years ago. Could never get it to function 
> properly on my TR4. Gave up in the end is it was all way too hard and 
> complicated. Engine always ran hot no matter what I did. I had an 
> electronic controller which gave variable speed to the pump unit. But 
> that didn’t make any difference in my case.
>

Unfortunately, pumps are almost always rated by their flow rate through 
an open orifice, and one has to figure in the pumping losses through the 
engine.  So, if an engine produces x amount of heat per minute, then the 
actual flow rate, given the specific heat of water, has to be able to 
remove x amount of heat per minute.  A cast-iron engine with lots of 
rusty-crusties in the passages is certainly going to have a flow rate a 
fair amount lower than an open orifice (not that those rusty-crusties 
aren't important--heat transfer off of rusty cast iron is higher than 
with any other metal because of the surface area).

The other big problem with pumps is that one needs to know their flow at 
specific head pressures, because without the pump being able to build 
pressure and still move fluid, hot-running engines will inevitably 
succumb to nucleate boiling and overheat.

In theory, one could have an electric pump that's more efficient than a 
mechanical one, in the same way that electric fans, with the maximum 
efficiency blade pitch matched to the motor rpm, are more efficient than 
engine-driven fans.  However, I suspect that the makers of the kits out 
there are assembling them from the parts available, not engineering them 
to requirements.


Cheers.

-- 


Michael Porter
Roswell, NM


Never let anyone drive you crazy when you know it's within walking distance....

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