I think it is time to take a look at the automotive water pump.
 There are 2 major types of pumps, centrifugal and positive
 displacement, we are interested in the centrifugal group.

 Within that group there are 2 types of designs; open impellor and
 closed impellor. Open impellor are used in almost all automotive
 water pumps.


 The open impellor type are used for their low cost of manufacture
 and their relative ease of cleaning, should they become blocked.


 The closed style is however far more efficient but is substantially
 far higher in cost to produce, and far harder to clean if they
 become blocked. Blockage in our situation is not a factor. Open
 style impellor pumps are never used on flammable or explosive
 materials as the clearance between the impellor and the volute can
 be reduced to zero by thermal expansion. Automotive pumps run with
 very high clearances to avoid the same problem, this makes them low
 efficiency.


 We must now consider the application they are being used on. In
 Industry the pump is designed around a set of parameters that suit
 the customers requirements, and in general used at a constant
 speed. In the case of the automobile and other internal combustion
 engines this speed can vary considerably.



 The automotive pump must be able to deliver sufficient flow at low
 rpm and or low speed and high engine load to cool adequately. If
 you double the speed of this pump you require the cube in energy,
 i.e. 2x2x2=8.


 Consider an engine running at 2000 rpm at idle and then at 6000rpm
 or higher as we do at cruise, the auto environment never for
 domestic use run at so high rpm for any length of time. You have
 increased the speed by a factor of 3, so now you require the cube
 of 3, 3x3x3=27.



 I have no argument with Pauls formulae for Volts x Amps = watts,
 and the conversion between HP to Watts, what is in dispute is that
 you have increased the rpm by a factor of 3 but have not increased
 the flow by anywhere near that factor, but are consuming 27 times
 the power. You could only possibly hope to increase the flow rate
 by a factor of 3 by using variable geometry impellors and volute.
 This aint going to happen.


 In any case to increase the flow by this amount and be able to
 exchange 3 times the heat is also not going to happen with a heat
 exchanger designed to suit the output of the pump So where does
 this leave us. It leaves us with a pump that is highly inefficient
 and a vast waste of energy, but is acceptable to the auto
 manufactures, and where do you think all that energy goes? Some is
 lost in slippage within the pump due to high clearances, the higher
 pressure is able to pass easily to the low pressure side thus
 reducing pumping efficiency, but the rest goes into heating the
 cooling water!!!


 Some European car manufactures have woken up to this and are using
 electric pumps, also many of the rotary racing boys here and
 probably elsewhere are using electric pumps. They consume a
 fraction of the power of a mechanical pump, but are highly
 efficient. I will be running an electric pump made by Davis Craig
 of Australia, check them out. I also Know of a tri rotor here in
 Tauranga that is a race car that has run an electric pump for some
 years.

 Andrew.  Campbell

 What kind of race car? What brand of electric pump? What size is
 the fuse?

 Paul Lamar



 Is there an advantage to using one of the racing water pumps, such
 as Re-medy or others, with or without a reduction pulley?

 https://www.google.com/search?q=mazda+rx8+racing+water+pump&tbm=isch&imgil=2gpHUwm9gUYUoM%253A%253BNIMFr80W67YWjM%253Bhttp%25253A%25252F%25252Fwww.rx8club.com%25252Fmazmart-88%25252Fre-medy-water-pumps-rx8-stock-158707%25252F&source=iu&pf=m&fir=2gpHUwm9gUYUoM%253A%252CNIMFr80W67YWjM%252C_&usg=__zjVVF3yl6aeTS1XbSpkdH_8Aq0g%3D&biw=1098&bih=1011&ved=0ahUKEwjr0-Dkk67TAhXGeCYKHQfwA0cQyjcISg&ei=ahr2WOv2MMbxmQGH4I-4BA#imgrc=sMZ6zvpWCp47wM:


Scott Gettings

Could be the RX8 pump impeller is a little crude.

To test it you would need a thermo couple embedded near the lower spark plug
and then do some flight testing. About the only automotive scenario that is
a valid water pump test is NASCAR racing where the engine runs near full power
for two or three hours. Some drag race engine have no cooling system at all
as the engine runs full power for only a few seconds.

Paul Lamar

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