> wrote in message
...
> On Fri, 02 May 2014 00:28:35 -0700, mike > wrote:
>
>>On 5/1/2014 9:08 PM, Rick wrote:
>>>
>>> "mike" > wrote in message
>>> ...
>>>> On 5/1/2014 4:46 PM, MLD wrote:
>>>
>>>
>>>> operation
>>>> can the pressure on the output side of the pump significantly exceed
>>>> the pressure on the input side?
>>>
>>>
>>>
>>> Yes, and it looks like a lot of you have no idea how much it can, and
>>> does.
>>>
>>I'd like to hear the rationale in a closed system.
> Restriction to flow affects the "head" of the pump. No restriction,
> no head pressure. A good water pump may produce a 5 psi head, and draw
> an equivalent depression on the low side of the pump for a maximum
> pressure differential of 10psi - but that is a "blueprinted" pump at
> optimal speed with an adequately restrictive radiator.
>
> Real world numbers are generally quite significantly less. Measured
> 3psi on BMW 328 just this week at 3000 RPM. Above and below 3000 it
> dropped off. That was with diluted coolant (about 20-25% glycol) due
> to having just repaired a leak and having the normal "fun" bleeding
> all the air out of the nasty little Kraut!!

Having performed thousands of automotive cooling system flow/pressure and
pump performance tests, I can say you have no idea, either.

Without getting into particulars, recently....5500 pump RPM...10 psi at the
pump inlet, 200+ GPM into the block at 80 PSI pump outlet pressure