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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 didnâ??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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<div class="moz-cite-prefix">On 5/12/2019 7:15 PM, Peter Vucinic via
Fot wrote:<br>
</div>
<blockquote type="cite"
cite="mid:!&!AAAAAAAAAAAYAAAAAAAAADpmE6eHDApHoEo2MzdQ3KnCgAAAEAAAAPQqZwPx6dBDkYOMNGopEUABAAAAAA==@netspace.net.au">
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<div class="WordSection1">
<p class="MsoNormal"><span
style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi
John,<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D">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 didnâ??t make any difference
in my case.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p>Â </o:p></span></p>
<p class="MsoNormal"><span
style="font-size:14.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p>Â </o:p></span></p>
</div>
</blockquote>
<p><br>
</p>
<p>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).<br>
</p>
<p>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.</p>
<p>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.</p>
<p><br>
</p>
<p>Cheers.<br>
</p>
<pre class="moz-signature" cols="72">--
Michael Porter
Roswell, NM
Never let anyone drive you crazy when you know it's within walking
distance....</pre>
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