At high RPM the pump sometimes pumps too little water, not because it is
turning too slowly but because it is turning too quickly!!! The phenomenon
of "cavitation" means that the pressure behind the blades becomes very
small, smaller in fact than the vapor pressure of water at whatever
temperature the engine is running (engineers, please forgive my vast over
simplivication). When this happens the pump effectively stalls and quits
pumping. Kinda like a slipping clutch, reducing engine power will allow it
to grab and then you can get back on the gas (then rebuild when you get
home.) Of course, it won't quit entirely but the flow is severely reduced.
A larger pump on the fan on those high revving engines, and perhaps a more
efficient water pump will provide better cooling because it will move more
water through the radiator.
Another case of less is more.
Hal
-----Original Message-----
From: owner-spridgets@autox.team.net
[mailto:owner-spridgets@autox.team.net]On Behalf Of Chris Kotting
Sent: Thursday, November 05, 1998 6:29 AM
To: 'Evangelos G. Makris'; Mostyn
Cc: SPRIDGETS
Subject: RE: cooling system question.....and more ramblings
Evangelos -
You've got it right, but I think he's talking about using a larger
crankshaft pulley, which would spin the waterpump, fan, and alternator
>faster<.
Chris Kotting
ckotting@iwaynet.net
On Thursday, November 05, 1998 8:35 AM, Evangelos G. Makris
[SMTP:emakris@hol.gr] wrote:
> Mostyn wrote:
> > 6. the sugestion for a larger pully is a great one also. It should
handle
> > the cavitation at higher RPM
>
> Larger pulley where? On the fuel pump, the crankshaft or the
> alternator?
>
> If my memory serves me right, a larger pulley on the water pump
> will make the fan turn slower, much like the gears on bikes, right?
>
> So, if the fan turns slower is cooling improved?
>
> Evangelos
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