Differential Pressure Testing Update

[Jim Allen]

Nothing much to report on currently. Thus far, I have data for the setup I am running now ( P1 w/10W30 MC Super Duty CJ-4/SM) at 12K miles but I am still collecting filters for new-state testing, which won't start until I have finished the 15K interval on the MC oil I am currently running.

I will be using 5W20 Castrol GTX for the test (I have almost two cases of SM laying around). Thus far, I have a MC FL820S, Bosch D3410 (both courtesy 2010FX4), Fram XG2 Ultra and Royal Purple to test DP. I don't intend to go out a buy every filter on the planet to test. I may get a couple of others on my own, but only if I get interested enough to test them.

Right now, it appears that what I was told by several engineering types at filter mfrs that bypass event are "infrequent" appears to be true. Even with a 12K filter and heavy oil, in normal driving (my normal), I rarely approach the DP where bypass is possible and then mostly when the oil is cold. I have wrapp the warm engine up to 5800 rpm with oil @ 175F and just barely got into bypass territory. Once or twice I have gotten on the engine cold (EOT < 50F), getting OP over 100 psi and even then DP was only about 9-10 PSI.

 

[ZeeOSix]

Originally Posted By: Jim Allen
Right now, it appears that what I was told by several engineering types at filter mfrs that bypass event are "infrequent" appears to be true. Even with a 12K filter and heavy oil, in normal driving (my normal), I rarely approach the DP where bypass is possible and then mostly when the oil is cold. I have wrapp the warm engine up to 5800 rpm with oil @ 175F and just barely got into bypass territory. Once or twice I have gotten on the engine cold (EOT < 50F), getting OP over 100 psi and even then DP was only about 9-10 PSI.


Good info Jim. Really appreciate you getting this test setup on your truck and reporting your test findings.

My theory way back was that even with cold oil, the flow volume of cold oil through the filter is reduced because the oil pump will go into pressure relief with less oil flow - thereby sending less oil to the filter. As you know, the combination of oil flow volume and viscosity due to the oil temperature, along with the flow resistance factor of the filter's media, determines the delta-P across the media.

It appears that even with cold oil and relatively high engine revs, that the filter's delta-P is still below bypass opening point. I could see where if the oil was really cold (ie, below zero) that the oil filter would go into bypass with some revs because the oil pump's pressure relief valve may not be able to regulate very well in super extreme conditions, and inadvertently send too much cold oil volume through the filter causing high delta-P and a bypass event.

 

[Texan4Life]

+1 thanks for the update!

 

[dnewton3]

Two thoughts here:

1) it's nice to see an experiment to back up theory, rather than the typical bench-race opinions we so often get around here.

2) I'd like to see how a "normal" filter performs (a Classic or such other normal offering). I'd be willing to purchase and send to you, if you're interesed.



The fact that you're seeing very few DP events (except in the expected cold oil early operations) means that fitlers are not loading up to a point of bypass. I realize that it's early in the testing, but I'm willing to make a prediction, and then we'll see if my mantra plays out.

As I've said before, macro wear data shows that differences between filtration efficiency really does not manifest into reality in the crankcase. When it comes to protection, as long as the OEM min specs are met, the wear is not statistically shifted if you use a super-premium filter or a decent normal filter. And that is because the level of protection is good enough to sustain the required level of cleanliness, and anything past that is moot generally speaking. Now, in micro-analysis cases, there might be some shift, but it takes a LOT of UOA data for one machine to prove this, and to date, I've not seen anyone here ever try this. And, I SERIOUSLY doubt there would be a payback relative to the cost; if you spent 2x more money (think Ultra to a Classic), would you get half the wear? NO! The data I've seen in industrial applications shows the law of diminishing returns creeps in, as your filtration improves. What you get with premium filtration is longer OCIs, especially with bypass filtration.

The delta P topic is similar; the bypass valve does not often go into bypass mode, and therefore it's construction, and location, and leaf spring type really don't make much of any difference, because they are not in action often. And what little they are in action, their atributes mean little as long as the function physically happens. The event of the bypass ation is WAY more important than whether it's at the dome or base end, leaf or coil spring, etc.

Finally, I predict that even "normal" filters are capable of filtering for a much further OCI than folks think, because if they don't load up to bypass frequently, they apparently have availble flow to sustain safe operation. Some folks might say "well, they flow for sure, but that's because they are open like a seive ..." But I would remind you that unless the wear data significantly shifts with those "seive like" pores, it's all moot.

 

[Jim Allen]

I have one "normal" filter in the mix, the MC FL820S donated by 2010FX4 and I hope to put some others in as well.

Dave, I generally agree with everything you said.

It looks to me like the "average" filter is somewhere around 93-95% @ 20um, absolute in the 35 um range. That's pretty good when you think about it. Looks to me like the average large filter (typical American V8 size) holds 12-18 grams of contamination. I have seen some averages of how much contamination is generated by an engine per mile of operation but I don't have a good enough handle on it to make any statements here. I could characterize it as "not a lot" but there are other factors like moisture and oxidation residue, both of which have an effect on the filter in a way that's not always easy to predict. Neither are much of a factor in engines with a "good" operational cycle (ie not a worst-case short hopper or something that gets fried in extreme heat).

The need for better filtration comes into play in certain situations, especially where contamination inputs are high. This would be true of many HD off-road engines. I think this may be why we only have those white paper test where they inject large amounts of contaminants artificially to measure wear. That is the venue where the most help is needed and where better filtration pays for itself. I think that those tests are valid in their own venue but not really accurate in representing the world of passenger car engines where contamination inputs are extremely low. The lack of testing may indicate that the engineers already know what we think we do... that it's not all that relevant, But the sales types glommed onto those HD engine tests as a tool to sell product but they don't accurately represent the situation generally found in the easy life of a modern street car or light truck. I do think they might apply more to older non-roller engines that naturally shed more metal, so maybe a '70s smallblock Chevy, or somesuch, is the ideal recipient for these new high efficiency fitlers that can clean the oil well and quickly.

 

[Coprolite]

If I had a used engine of unknown provenance, I would use the highest capacity filter that I could as opposed the the normal view here that the cheapest filter is the way to go since short OCI and heavy cleaning is happening. This would be the optimal time to have the DP setup to govern FCI length.

Of course, it is also usually the time that people can't afford such luxuries...

 

[dnewton3]

I will supply one Purolator Classic and one Fram EG (OCOD) for the testing.

Those who cringe and the thought of such inferior filters are advised to avert their eyes from the horror ...

 

[ZeeOSix]

This is always a good thread to link to for added reading about delta-P across an oil filter. Kind of ties in with what Jim is doing with his test setup.

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2088643&page=1

 

[ZeeOSix]

Originally Posted By: dnewton3

The delta P topic is similar; the bypass valve does not often go into bypass mode, and therefore it's construction, and location, and leaf spring type really don't make much of any difference, because they are not in action often. And what little they are in action, their atributes mean little as long as the function physically happens. The event of the bypass action is WAY more important than whether it's at the dome or base end, leaf or coil spring, etc.


When you say "leaf spring" bypass valve, are you referring to the flat spiral type used on some Purolators? Or are you referring to the leaf spring located in the dome end that is supposed to hold all the guts of the filter tightly together. If the latter, then that kind of leaf spring is not associated with the bypass valve.

 

[Jim Allen]

Originally Posted By: ZeeOSix
Originally Posted By: dnewton3

The delta P topic is similar; the bypass valve does not often go into bypass mode, and therefore it's construction, and location, and leaf spring type really don't make much of any difference, because they are not in action often. And what little they are in action, their atributes mean little as long as the function physically happens. The event of the bypass action is WAY more important than whether it's at the dome or base end, leaf or coil spring, etc.


When you say "leaf spring" bypass valve, are you referring to the flat spiral type used on some Purolators? Or are you referring to the leaf spring located in the dome end that is supposed to hold all the guts of the filter tightly together. If the latter, then that kind of leaf spring is not associated with the bypass valve.


I was not clear. I mean the leaf spring that olds the filter element in place.

 

[ZeeOSix]

Originally Posted By: Jim Allen
Originally Posted By: ZeeOSix
Originally Posted By: dnewton3

The delta P topic is similar; the bypass valve does not often go into bypass mode, and therefore it's construction, and location, and leaf spring type really don't make much of any difference, because they are not in action often. And what little they are in action, their atributes mean little as long as the function physically happens. The event of the bypass action is WAY more important than whether it's at the dome or base end, leaf or coil spring, etc.


When you say "leaf spring" bypass valve, are you referring to the flat spiral type used on some Purolators? Or are you referring to the leaf spring located in the dome end that is supposed to hold all the guts of the filter tightly together. If the latter, then that kind of leaf spring is not associated with the bypass valve.


I was not clear. I mean the leaf spring that holds the filter element in place.


Question was in response to DN3's post.

 

[Jim Allen]

Originally Posted By: ZeeOSix
This is always a good thread to link to for added reading about delta-P across an oil filter. Kind of ties in with what Jim is doing with his test setup.

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2088643&page=1


Excellent reference, thanks! It really does seem to correlate well, though I can't tell how much my oil pump is delivering at any moment in time. I do have some specs on it though, so I might be able to get a rough Idea of GPM by rpm.

 

[dnewton3]

Originally Posted By: ZeeOSix
Originally Posted By: Jim Allen
Originally Posted By: ZeeOSix
Originally Posted By: dnewton3

The delta P topic is similar; the bypass valve does not often go into bypass mode, and therefore it's construction, and location, and leaf spring type really don't make much of any difference, because they are not in action often. And what little they are in action, their atributes mean little as long as the function physically happens. The event of the bypass action is WAY more important than whether it's at the dome or base end, leaf or coil spring, etc.


When you say "leaf spring" bypass valve, are you referring to the flat spiral type used on some Purolators? Or are you referring to the leaf spring located in the dome end that is supposed to hold all the guts of the filter tightly together. If the latter, then that kind of leaf spring is not associated with the bypass valve.


I was not clear. I mean the leaf spring that holds the filter element in place.


Question was in response to DN3's post.

Sorry for the misleading statement.

I was tying to show the variety of construction types and ended with a mixed metaphor so to speak. There are all kinds of bypass valves and locations, different media types, multiple locating springs, different materials for ADBV, etc.

Unfortunately, it's not hard for my super fast typing to get ahead of my incredibly average brain speed ...

My apologies.

 

[rrounds]

I got a question, does the bypass open just once during a bypass event or does it open and closed many times during one event? On some cars the oil filter is as small as what I put on my motorcycle, so when you start the engine and its 7*f out and the fast idle is at 2400 rpm I can see the bypass fluttering open and closed until the oil thins a little and flowing better. It might not happen with 0/20 oil but a lot of older cars still run 10/40 or thicker.

ROD

 

[dnewton3]

For it to "flutter" it would have to be on the cusp of the delta-P intialization point, and also have a variable resistance or input that was causing a pulsation.

I seriously doubt if flutters open/close for more than a fraction of a second, if at all.

Even if it did, it would be such a small volume relative to the total flow, that it would not matter at all. To "flutter", it would have to be at the extreme low end of the delta-p to overcome the spring pressure, but then the "relief" of pressure from opening would close the delta-p back off, and the spring would seat the valve. And then the delta-p would escalate again, etc, etc.

Does it happen? Maybe.
Can you detect it? Most likely not.
Can you avoid it? Probably not.
Will it hurt anything? Almost assuredly not.
Will it affect filtration to a point where wear is generally statistically affected? Absolutely not.

You're worrying about minutia that is so small and inconsequential that it's totally moot.
But then again, this is BITOG; it's what we do here ...

Allow me to quote myself:
Originally Posted By: dnewton3
Two BITOGers could argue the merits of differences in Skim and 2% milk, relative to the viscosity of fat content, relating to the ability to swallow one's breakfast cereal ...

 

[Jim Allen]

The bypass will respond to fluctuations in oil pressure so if it's right at the opening pressure it may do something like a flutter as it responds to slight pressure changes (oil pressure does fluctuate a few psi in each direction).

In any case, bypass opening isn't always (or often) a complete, full opening of the valve and a total bypass of the media. It opens just enough to relieve the pressure over it's set limit so oil is almost always flowing thru the media and the partly open bypass at the same time.

I am not clear how the industry defines a bypass "event," because I didn't ask for a definition. From the context of the discussion, I interpreted it as when the valve opens to any degree and fully closes.

I hate to keep harping on my own truck... but that's the only experience I have where I can watch differential pressure in real time. When the truck starts, it flares to around 2200 rpm. When the (10W30) oil is cold, 30-40F, DP will bump right at the point where the bypass is beginning to open. The spec for the P1 currently fitted is that the bypass starts to open at 8 psi and is fully open at 16. I don't have the datalogs right here in front of me but I think the highest I have see is a tick under 10 psi... but that was a full-bore acceleration test to 5200 rpm with the oil at 45F... not MY norm, certainly. At that temp, the oil is at over 30 cSt... about as thick as 140 grade gear oil. If I drive sedately during warmup, I can keep the DP below the bypass cracking point (cracking being the point where the valve just starts to "crack" open). Remember that I am using an oil that is much heavier than spec'ed and I see cold oil pressure of 80-90 psi regularly (the oil pump relief begins to bypass at around 80 psi) even driving sedately. When I get on it cold, I have seen 110 psi or so.

What things can you do to avoid filter bypass?

1) Run the spec'ed oil viscosity, or "go thinner."

2) Use oils with better cold flow performance.

3) Drive sedately when the oil is cold.

4) Don't run the engine at high revs until the oil is fully warmed up.

5) Use a filter with a higher bypass specification (I'll leave it to you to think of the caveats that will go with that).

6) Use an oil filter with more media area (oversized, but with roughly the same efficiency as the one you are replacing) or one with high capacity, such as a fully synthetic (blown glass) type media (not a cell/syn blend).


Overall, just chill. The bypass won't open often, even if you don't do much to try and avoid it. When it does open, remember it's usually of short duration and a high percentage of the oil is still being filtered.

 

[ZeeOSix]

Jim, is your data acquisition system fast enough to see if the bypass valve does "flutter" some when it's active? How often does your logger record data?

 

[Jim Allen]

Originally Posted By: ZeeOSix
Jim, is your data acquisition system fast enough to see if the bypass valve does "flutter" some when it's active? How often does your logger record data?


In theory it does. It collects data 5X per second, so in that second, if I saw pressure at 9, 10, 1, 9, 10 I would imagine that could be interpreted as flutter ... but I'm not generally. Only occasionally do I see any change in data during that second and it's never much. Several possible reasons for that, including that the flutter (if any) is pretty slow.

I'm still figuring out how to post the data. Even when I sort out all but the data I'm interested in, just three minutes of recording results in a 14 page printout of data. I'm probably just going to chop out some of the more interesting parts to post... when I have time to sort thru it all.

 

[ZeeOSix]

Originally Posted By: Jim Allen
Originally Posted By: ZeeOSix
Jim, is your data acquisition system fast enough to see if the bypass valve does "flutter" some when it's active? How often does your logger record data?


In theory it does. It collects data 5X per second, so in that second, if I saw pressure at 9, 10, 1, 9, 10 I would imagine that could be interpreted as flutter ...


I would interpret that as a bypass event. If you saw that pattern repeatedly every few seconds, then I'd call that a slow "flutter".

 

[rrounds]

Some Subaru filters have a 20LBS psid filter and most Fords have 8LBS psid filters, I wonder why Subaru specs a higher bypass on their engines? Honda filters for the S2000 also have a high psid, higher than any other oil filter I've tested. Is it to make sure most if not all the oil goes through the filter, even if its cold. With such a high psid I would think it would lower the oil pressure a bit to the bearings when you start it up when its cold outside. That is one reason why I run the Baldwin B7042 oil filter, over twice as large as the Honda filter for the S2000.

ROD