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Ok, a couple more points to make.
1. Todd has done something very useful, *started*
getting performance data with the EWP.
2. What was the outside temperature? This makes a
difference, because there are two ways you can get enough cooling -- really cool
the water down before it goes into the engine, with a small flow rate, or use a
higher flow rate and a smaller delta T. The first will work in cooler
weather, he may be flow limited in hotter weather. Time and *testing* will
tell.
3. The actual horsepower required to pump water
through the system is *not* all that much. I will post some results later today
that I derived from my *actual tests* on an engine driven pump mounted on the
block. (on different computer). Dale and Jim make a good point about the water
pump thrashing when the thermostat closes -- drives up the power
required.
4. with respect to the quote below, I have long
suspected that Davies Craig would be looking for a measurement of engine power
saved that made their EWP look as favorable as possible. So they *might* quote
the highest power drain that a water pump could absorb.
5. As I stated before, when I was testing the stock
pump by driving it with an electric motor, I could easily drive it with my
table-saw motor up to 5400 rpm. Paul wanted to see what it would do at
7000 rpm, so he sent me a larger pulley, and I tried it. That increased the
power requirement enough that the motor would blow the circuit breaker.
The power absorbed by the pump clearly goes up as the square (or cube?) of the
RPM, so don't overspeed your pumps!
As another point to be considered, there has been
previously discussed the need for higher volume flows to prevent local hot spots
around the spark plugs from causing local boiling. I am not sure how to
test this in the EWP case.
Bill Schertz
<... "up to 30 HP." ... current drain
is .134 HP ... Maximum flow rate of [the EWP is] only 88L/min compared with a
maximum of 240L/min for the same engine using an older mechanical water pump
design ...>
Beware people
with an agenda - like "... figures don't lie, but liars figure
...
Most folks with an agenda will
exaggerate to make a point.
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