+1
I imagine this will be a majorly lurked thread, so while I don't like resurrecting them, I feel the above deserves to be in here.
Rotella T6 15w40 at Walmart
- Thread starter Jay Freddy
- Start date
I imagine this will be a majorly lurked thread, so while I don't like resurrecting them, I feel the above deserves to be in here.
^^^ Yep, pumps produce flow ... and pressure is what is created when that flow is going through a resistive flow path. A pump with zero restriction on its outlet will not "create" any real pressure. The more flow resistance you put on the pump outlet, the more pressure is produced to make the flow go through the resistive flow path.
True...
The pump delivers a rate of flow. That flow meets with (and
hopefully overcomes) a resistance in the system and the result of this
is pressure. Therefore, what is read on the gauge is NOT the amount of
pressure the pump is putting out – it is the amount of resistance that
is currently being overcome in the system... therefore the rate of
flow in our engine oil is more desirable than the amount of pressure...
In case the OP is wondering what we are talking its about a positive
displacement pump namely a Gerotor... here is a widely used pump that
sports the advantages listed below the animation but on the question
whether a change in temp or a change viscosity will change the GPM
flow rates I'll refer to a engineer at Titanspeed pump manufacture...
Given your gerotor pumping system would I see more GPM running a 30
versus a 40 grade oil or would the GPM be the same???
Quote Bob Sanders Titanspeed pump company...
"Slightly more would flow as there is less viscosity which resists
flow."
The choice word "Slightly" is underemphasized given PD pump curves.True...
The pump delivers a rate of flow. That flow meets with (and
hopefully overcomes) a resistance in the system and the result of this
is pressure. Therefore, what is read on the gauge is NOT the amount of
pressure the pump is putting out – it is the amount of resistance that
is currently being overcome in the system... therefore the rate of oil
flow in our engine is a more desirable parameter than the amount of pressure...
In case the OP is wondering what we are talking its about a positive
displacement pump namely a Gerotor... here is a widely used pump that
sports the advantages listed below the animation but on the question
whether a change in temp or a change viscosity will change the GPM
flow rates I'll refer to a engineer at Titanspeed pump manufacture...
Given your gerotor pumping system would I see more GPM running a 30
versus a 40 grade oil or would the GPM be the same???
Quote Bob Sanders Titanspeed pump company...
"Slightly more would flow as there is less viscosity which resists
flow."
The choice means the 30 and 40 are not equal and the advantage goes to the 30...
Actually the opposite ... a higher viscosity will make the PD pump more efficient - ie, less "pump slip".
How Much Does Viscosity Affect Pump Performance?
Viscosity will affect positive displacement and rotodynamic pumps differently. In positive displacement pumps, higher viscosity limits leakage (slip), increasing the displacement volume and volumetric efficiency.
www.pumpsandsystems.com
"Viscosity will affect positive displacement and rotodynamic pumps differently. In positive displacement pumps, higher viscosity limits leakage (slip), increasing the displacement volume and volumetric efficiency."
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Nope, see post #46.
Yeah if your PD pump is giving you even noticeable variable flow rate at all expectant operating temps under the bypass limit, then the engine designer picked a shoddy PD pump.
