"Guv Bob" > wrote in message
m...
> "MLD" > wrote in message
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>>
>> "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
>
> Thanks. Still looking for RPM vs Floweret

You're right, not an easy thing to find. Why not give one of the many
manufacturers a call and ask for what you want.
MLD


>