Differential Pressure Data, Pure 1 & Motorcraft

[DudeNiceRide]

Originally Posted by ZeeOSix
Originally Posted by DudeNiceRide
Why is this a sticky'd topic? Study is appreciated, but seems pretty unscientific from which to draw hard conclusions. They do make laboratory test standards and require calibrated gauges for this stuff for a reason.

It's more scientific than what anyone else has done and shared on this board. He mentioned his setup and instrumentation, which seemed pretty decent. It's good info IMO.


Sorry, I'm just a seasoned lab-rat who likes his data squeaky clean. My apologies for lightly bashing the work here.

It is rather intriguing how infrequent the PRV opens. I wonder how some of the newer lube systems would fair given the variable displacement pumps which only give the engine "what it needs" to improve efficiencies, MPG, and so on (?). At red-line, the VDP wouldn't necessarily run 1:1 off the crank RPM like the old-style mechanical pumps.

Also have to remember most car/truck hydraulic circuits are equipped with a pressure regulating valve (PRV) to limit the system oil pressure. If the system pressure exceeds the PRV, the oil filter may not even see any additional oil or pressure -- it will bleed off through the PRV to the crankcase.

 

[CR94]

Originally Posted by DudeNiceRide
... It is rather intriguing how infrequent the PRV opens. .... If the system pressure exceeds the PRV, the oil filter may not even see any additional oil or pressure -- it will bleed off through the PRV to the crankcase.
Don't confuse the system pressure-relief valve with the filter bypass valve.

I suspect the bypass valve opens more frequently on typical newer vehicles than it during in the test in question, because filters have shrunk so much---partially compensated by the trend to lower viscosity oils.

 

[ZeeOSix]

Originally Posted by DudeNiceRide
It is rather intriguing how infrequent the PRV opens. I wonder how some of the newer lube systems would fair given the variable displacement pumps which only give the engine "what it needs" to improve efficiencies, MPG, and so on (?). At red-line, the VDP wouldn't necessarily run 1:1 off the crank RPM like the old-style mechanical pumps.


The goal of variable output oil pumps is to reduce the oil volume going to the engine, which means the filter will have less flow and therefore less delta-p. So the BPV should open even less often.

Originally Posted by DudeNiceRide
Also have to remember most car/truck hydraulic circuits are equipped with a pressure regulating valve (PRV) to limit the system oil pressure. If the system pressure exceeds the PRV, the oil filter may not even see any additional oil or pressure -- it will bleed off through the PRV to the crankcase.


As CR94 said, the BPV and oil pump PRV are not dependent on each other. The filter BPV only operates from the delta-p across the filter, and delta-p in the filter is not caused by how much oil pressure is in the system, but rather how much oil flow (and the viscosity of the oil) is going through the filter. If the flow was zero, and the pressure was 100 PSI, then the delta-p across the filter would be zero.

 

[Kjmack]

Bumped for a great read