"Guv Bob" > wrote in message
m...
"MLD" > wrote in message ...
>
> > wrote in message
> ...
> > On Sun, 21 Apr 2013 18:50:29 -0700 (PDT), "
> > > wrote:
> >
> >>On Apr 21, 6:11 pm, Tony Hwang > wrote:
> >>> Ashton Crusher wrote:
> >>> > I was thinking of putting a higher pressure cap on one of my cars to
> >>> > increase the factor of safety against boiling. Looking thru the web
> >>> > for info on the likelihood of changing from 7 psi to 13 psi causing
> >>> > leaks I found little on that issue but did find a couple references
> >>> > to
> >>> > the pressures created by the water pump. One site boasts of a 19
> >>> > PSI,
> >>> > $25 cap to get you thru your "hard driving".
> >>> >http://www.mishimoto.com/mishimoto-h...tor-cap-13-bar....
> >>> > Thought I'd see if anyone else has heard of this. The claim was that
> >>> > the water pump could create over 30 PSI of pressure. Since that is
> >>> > double the normal operating pressure of most modern cars I find it
> >>> > hard to believe. If the system was at full 15 psi of pressure while
> >>> > the car is idling and then your floored it and ran it up to near
> >>> > redline and created another 30psi of additional pump pressure, or
> >>> > even 10 psi of additioingnal pressure downstream at the radiator
> >>> > cap,
> >>> > you
> >>> > would immediately cause the system to have to vent to the overflow
> >>> > to
> >>> > relieve this higher pressure. I've never seen a car vent due to me
> >>> > revving the engine up while I'm working on it. Thoughts?????
> >>>
> >>> Hi.
> >>> There is a over flow bottle for coolant/anti-freeze. Ever
> >>> cleaned/flushed your rad. and maintain proper level of
> >>> coolant/anti-freeze in your rad.? If the car is old, messing with cap
> >>> can spring
> >>> a leak.- Hide quoted text -
> >>>
> >>> - Show quoted text -
> >>
> >>AMEN!
> > A water pump cannot produce system pressure because it just moves
> > water from one side of the pump to the other. Expansion due to heat is
> > what builds pressure..
>
> I guess you need to know how a centrifugal pump works. Pressure rise
> across the pump is function of the square of its speed. Double the pump
> speed and the delta P across the pump increases 4X. Expansion due to
> heat
> will increase system pressure if it is in a closed system. If a fluid can
> expand without being constrained---no significant change in pressure.
> MLD

MLD, do you know where to find a flow rate vs RPM curve for any common stock
water pumps? I'm surprised I can't seem to find anything mfr spec curves
at the various mfrs and parts houses. Doesn't matter what mfr or vehicle --
just any common street car single head pump.

Found this Flow vs Delta P characteristic.
http://www.bing.com/images/search?q=...urve&FORM=IGRE

MLD