Wix re efficiency increasing with use

[ZeeOSix]

I can see that on a race engine that barely makes any oil pressure at idle. Most of our vehicles are at pump relief pressure by 1,500rpm. As the engine runs faster more oil goes through the oil pump pressure relief. The engine could have the same oil pressure from 1,000rpm to 6,000rpm.

Sounds like a variable flow oil pump. If so, they still increase flow above a certain RPM. There's no way the engine is getting the same oil flow volume at idle and 6000 RPM. They are usually two-stage if ECU controlled, and have a low flow below a certain RPM, then switch to a high flow above that. Variable flow PD pumps are designed to save a very low amount of HP in oil pumping power (run the hydraulic pumping HP equation), but they also cut back the oil flow at higher RPM which can be controversial on if they will actually provide more than the bare minimum oil flow to keep the engine healthy. If designed right they should work fine, but if they are designed on the ragged edge of enough flow vs RPM then that's another issue. I'm glad none of my vehicles have variable flow oil pumps, give me old fashioned PD pumps.

What part of the engine uses more oil as the engine runs faster? Assuming the engine isn't a Ford 7.3 or 6.0 diesel.
Only thing I can think of is hydraulic lifters maybe.
I'll be sure not to use fiberglass hydraulic filters any more. Sold, case closed.

Journal bearings and oil splash or piston oil squirters need to flow more as engine RPM increases. And oil flow is used to help cool parts they come in contact with. Any part of the engine that doesn't get a bare minimum flow of oil is going to suffer at some point.

 

[ZeeOSix]

Air filters do it too. The air filter test is ran at fixed speed. Even project farm tests show a surge of dirt when the flow is increased. That's why I shop vac off my air filter front and back every oci.
My dodge Dakota beater uses around 70 to 100cfm choohing down the highway at 65mph. I go to pass a tractor trailer and floor it then it's using somewhere around 400cfm while constantly vibrating from the engine and going over bumps and washboarded road surfaces.

Yeah, that's why I called that example "A leaf catcher air filter working on cake theory". I think any filter could shed some already captured debris if the flow going through it is increased enough. But at a steady flow rate, air filters will get more efficient due to cake layer, whereas an oil filter will get less efficient (some more than others depending on media design and performance) with loading, as seen in the ISO efficiency test. Both will shed some debris to some degree with flow increase and dP pulsations. Watch that video in post 38, and even that special metal fiber filter had a very small decrease in efficiency due to flow pulsations. Losing efficiency from dP pules and losing efficiency as the filter loads up a constant flow rate are two separate things going on.

I'd venture to say that air filters that are higher in their efficiency rating are going to be less susceptible to debris shedding with large dP changes due to large flow rate changes going through them - like going from idle to redline at WOT.

 

[ZeeOSix]

My kid got a little optical and digital microscope for Christmas maybe I can use it to count particles.

Could at least look at media with light behind it and come up with some kind of "efficiency" estimate, lol.

 

[ZeeOSix]

Then why do I always see a dirty intake behind hind a heavily loaded air filter that should have been changed a long time ago?

Even high efficiency air filters let some particles through, as none are 100% efficient. Maybe if you rigged up a HEPA filter out of a clean lab that would be pretty close to a 100% efficient air filter. And of course if there is a leak around the filter's seal it's going to let some debris past the air filter.

 

[ZeeOSix]

Liquid under pressure behaves differently than air.

To add ... the forces from fluid flow is much greater than from air due to the huge viscosity difference. A person can stand in a 25 MPH wind, but look at what happens if they stand in a 25 MPH flow of water, or even if a car is in a couple feet of water flowing at 25 MPH. Same thing is going on as the air or oil flows through the media of a filter. The oil flow will provide much more force from the flow on whatever it flows past while it goes through a constant area of media. Increasing the total flow area of the media will bring down the velocity through the media, and therefore the flow forces.

 

[ZeeOSix]

My Truck has 2 fuel filters but I think they are the same efficiency as there are no identifying marks on the filters like primary or secondary.

The filters are monitored and the DIC has a countdown. When they get replaced the % drops quickly and then slows down considerably as time progresses. Not sure if they are getting more or less efficient during the last 20% of their life but I change them when they drop to less than 10%.

Are they in series or parallel? If in series, I'd think one is a pre-filter for the 2nd one.

 

[Pablo]

To add ... the forces from fluid flow is much greater than from air due to the huge viscosity difference. A person can stand in a 25 MPH wind, but look at what happens if they stand in a 25 MPH flow of water, or even if a car is in a couple feet of water flowing at 25 MPH. Same thing is going on as the air or oil flows through the media of a filter. The oil flow will provide much more force from the flow on whatever it flows past while it goes through a constant area of media. Increasing the total flow area of the media will bring down the velocity through the media, and therefore the flow forces.

PV=nrt

Not going to compress a liquid

 

[ZeeOSix]

PV=nrt

Not going to compress a liquid

Yeah, but fluid/air compression isn't a factor in flow going through filter media for air and oil filters used on vehicles.

 

[CleverUserName]

Are they in series or parallel? If in series, I'd think one is a pre-filter for the 2nd one.

I'm 99% they are parallel based on the sensor locations. It also makes sense as they are the same filter there are just 2 of them.

It kinda seems like they filter better as they load up with stuff based on the what I see with the % tracking down with mileage.

 

[Pablo]

Yeah, but fluid/air compression isn't a factor in flow going through filter media for air and oil filters used on vehicles.

True enough just pointing out a difference

 

[ZeeOSix]

I'm 99% they are parallel based on the sensor locations. It also makes sense as they are the same filter there are just 2 of them.

It kinda seems like they filter better as they load up with stuff based on the what I see with the % tracking down with mileage.

If they are in parallel the total media area is doubled, and the flow velocity through them is probably very low. In that case, it's possible that they can get more efficient with use. It's all about the velocity of the flow going through the media.

Oil filters used on a typical road vehicle are relatively small - some seem very small for the engine they are on - and the media area is only around 80 to 200 sq-in for most oil filters. And there can be as much as 10+ GPM of oil going through them at high engine RPM. So it's no wonder they get less efficient with loading at those flow rates if the media isn't designed well to hold already captured debris. Even the filters that were 99% @ 20 in the Ascent ISO efficiency test lost some efficiency, but it was very small compared to the lower efficiency filters.

 

[oil pan 4]

Sounds like a variable flow oil pump. If so, they still increase flow above a certain RPM. There's no way the engine is getting the same oil flow volume at idle and 6000 RPM. They are usually two-stage if ECU controlled, and have a low flow below a certain RPM, then switch to a high flow above that. Variable flow PD pumps are designed to save a very low amount of HP in oil pumping power (run the hydraulic pumping HP equation), but they also cut back the oil flow at higher RPM which can be controversial on if they will actually provide more than the bare minimum oil flow to keep the engine healthy. If designed right they should work fine, but if they are designed on the ragged edge of enough flow vs RPM then that's another issue. I'm glad none of my vehicles have variable flow oil pumps, give me old fashioned PD pumps.


Journal bearings and oil splash or piston oil squirters need to flow more as engine RPM increases. And oil flow is used to help cool parts they come in contact with. Any part of the engine that doesn't get a bare minimum flow of oil is going to suffer at some point.

If the skirt squirters are only getting say 70psi at 1,500rpm and 70psi at 6,000rpm how are they flowing more oil?

 

[ZeeOSix]

If the skirt squirters are only getting say 70psi at 1,500rpm and 70psi at 6,000rpm how are they flowing more oil?

I didn't claim they get more oil in the case you're describing - obviously if they are fed with 70 PSI then they flow a certain amount based on the oil viscosity. I basicakly said as engine RPM increases it needs a minimum oil flow to all parts to protect them from wear and damage, and getting oil to the cylinder walls and oil from a squinter to the bottom of the piston to also cool it are all parts of the required flow volume from the pump. Oil flow through the journal bearings also helps cool them. Start cutting the oil flow from the pump more and more, and a lack of lubrication will result at some place in the engine at higher RPM. That's why engines need more oil flow as the RPM increases.

Do you have an oil flow output volume of the pump vs engine RPM graph for this engine? Or even a pressure vs engine RPM graph if it's a two stage variable output pump? And what's the location of the oil pressure sensor? Does it show there is actually a constant 70 PSI from 1500 to 6.000 RPM with the oil at a constant temperature? Don't think even a computer controlled oil pump would be programmed like that. Why would the engine need the same oil flow at 1500 RPM then it needs at 6000 RPM? ... which is what would be happening if there was 70 PSI at both 1500 and 6000 RPM. The main purpose of variable volume pump is to decrease the flow volume more than a standard PD pump at lower RPM to cut pump HP and save fuel - a thing to try and meet CAFE. And it's possible the pressure you are seeing is at some other location besides after the oil filter ... wouldn't know without seeing the details of the oiling system and pump design. Need to know the oil flow volume going into the engine vs RPM to know exactly whats going on.

 

[oil pan 4]

My Truck has 2 fuel filters but I think they are the same efficiency as there are no identifying marks on the filters like primary or secondary.

The filters are monitored and the DIC has a countdown. When they get replaced the % drops quickly and then slows down considerably as time progresses. Not sure if they are getting more or less efficient during the last 20% of their life but I change them when they drop to less than 10%.

Every diesel engine that has 2 fuel filters I've ever bothered to look up has a 20 to 40 micron primary and a 15 to 4 micron secondary.
I'm starting to see some after market 2 to submicron secondary filters.

???

Not sure I follow?

You are saying the intake system is dirty after filter?

Yeah seen it plenty of times on neglected engines.

 

[CR94]

[Deleted]

 

[Pablo]

Every diesel engine that has 2 fuel filters I've ever bothered to look up has a 20 to 40 micron primary and a 15 to 4 micron secondary.
I'm starting to see some after market 2 to submicron secondary filters.
Yeah seen it plenty of times on neglected engines.

Filter failed- time, miles, conditions

 

[CR94]

Then why do I always see a dirty intake behind hind a heavily loaded air filter that should have been changed a long time ago?

Because there's a tear or other hole in it? I've never seen dusty intake beyond the air filter, despite running them longer than most do.

 

[GW.]

Intake plenums and throttle bodies get dirty from PCV valves all the time. Dirty crankcase vapors are to blame.

 

[Pablo]

Intake plenums and throttle bodies get dirty from PCV valves all the time. Dirty crankcase vapors are to blame.

Sure but shouldn’t be dusty or abrasive

 

[oil pan 4]

Because there's a tear or other hole in it? I've never seen dusty intake beyond the air filter, despite running them longer than most do.

Yeah that's what I thought too. Only ever found a hole once, appeared to be chewed by a mouse.