Some water pump stuff:
Inside BMW's Latest Powertrain Technologies
Water Pump Tech
OK here, from a piece regarding sensors for centrifugal water pumps:
Quote:
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Alternately, low load sensors can detect:• Minimum flow• Dead-heading• Flow restriction (i.e., plugged discharge filter or strainer,clogged spray nozzles, closed discharge valve, etc
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http://www.warrender.com/upload/prod...28dab2a7fd.pdf.
So me thinks automobile water pumps could cavitate just like that hair dryer and not like that boat, were flow to be stopped.
But then... the flow isn't ever stopped even when the stat is closed. Circulation is constant through head and block.
Now I think whether t-stat is open or closed likely has very small effect on pump load- too small to matter. For what my opinion on that is worth.
And:
Quote:
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In centrifugal pumping applications with no static lift, power requirements vary, as the cube of the pump speed and small decreases in speed or flow rate can significantly reduce energy use. For example, reducing the speed (flow rate) by 20% can lower input power requirements by approximately 50%.
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http://www1.eere.energy.gov/industry...pdfs/38949.pdf
Combine that with the SuperChevy dyno stuff, and underdriving the water pump can save HP but don't do it at the expense of low rpm cooling. And they didn't even bother reporting testing below 3000 rpm cuz it was too small.