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  #81  
Old 09-05-2022, 09:44 AM
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DanH DanH is offline
 
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I recently got interesting in oil filters. Ran across this thread while searching something else. I'll bet that happens a lot. A few random notes....

Micron ratings come in two flavors, absolute and nominal. Neither is useful for decision making without also stating the beta value, effectively the percentage of a particular particle size captured by the filter.

I can claim my T-shirt will stop a 20 micron particle, and it probably will. However, the beta may be 2, i.e. 50% efficient, i.e. half the 20 micron particles pass through. Micron stated without a beta is just talk.

Most filter manufacturers test for a dual beta, i.e. beta at two particle sizes. If it's not published, ask. For example, the NAPA 1515 is a Wix 51515. The nominal micron rating is 21, but note the beta values, listed as 2/20=6/20. It means beta is "2" for a 6 micron particle and "20" for a 20 micron particle. A 2 beta means it is stopping 50% of the stated particle size, while a 20 beta is 95%.

Now look at the listing for bypass valve setting, 8 to 11 psi, about 25% lower than the bypass setting specified by Lycoming and Continental. It means dirty oil is bypassing the filter element more often than it does with a xx108 or xx109 internal bypass aviation filter.

Which raises another point. Screwing a NAPA 1515 onto a Lycoming adapter intended for use with a xx110 or xx111 filter effectively disables the adapter's 11-15 psi bypass. The 1515's bypass opens at a lower pressure.

A lower bypass opening pressure has nothing to do with burst pressure. The bypass relieves pressure across the filter element, but does not change can pressure.

Quote:
Originally Posted by Northernliving View Post
...I decided to cut some auto filters open after my last oil change for the purpose of looking at and measure some of the physical differences to the Tempest SpinEZ AA48110-2 filter I had been using.
These all seem to be good, well-constructed filters. The biggest difference that I noted was how the bi-pass filter was constructed. In the SpinEZ filter, it is internal to the filter spindle, the Wix had a spring at the filter end (bottom) and the entire media moved to open the bi-pass, and the K&N had a small simple spring bi-pass an the end (bottom).
Thank you Brian, but there are two misconceptions here. First, the AA48110-2 has no internal bypass, nor does the larger 48111. Same for the Champion versions. Pressure does not move the element. The bypass valve is in the engine's filter adapter. The leaf spring merely locates the element and holds it against the base plate. Same is true of the big coil spring found in the same locations in other filters.

The Wix bypass valve is the small top hat module sandwiched between the base plate and the filter element. It is self-contained; bypass flow is in through the holes you see around the perimeter, exiting into the center bore. Wix filters with no bypass substitute a module with the same external shape, but having no holes, internal diaphragm seal, or spring. It's just an inert filler.

The K&N pictured here does indeed have a poppet valve bypass, very similar to the bypass currently installed in the 108 and 109 aviation filters. I have not looked up its pressure rating.
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Last edited by DanH : 09-05-2022 at 09:52 AM.
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  #82  
Old 09-05-2022, 10:12 AM
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Toobuilder Toobuilder is offline
 
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There is often a lot of discussion concerning the "clogged filter bypass" scenario... How often does this actually occur, and even then, what is the actual realized downside? A reduction in TBO by 5 hours? Not that long ago, these engines had nothing but a course screen to keep the chunks at bay. Even the cheapest automotive filter is more effective at cleaning oil than the engine was designed for, so is it really an issue if you get a bypass every now and then?

The fact is, the "best" full flow filter is a compromise between filtration and flow. If we want enough flow to keep the bearings alive, it HAS to pass trash big enough to wedge in a bearing clearance and remove metal.

A paper filter is better than a perforated screen, but "clean" oil is relative.

A little research on "bypass oil filtration" is worth the time. These filters are so fine they will even strip the additives out of the oil (in addition to ALL the trash), but they dont flow enough to keep the bearings alive at full flow. Cant have it both ways.
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  #83  
Old 09-05-2022, 10:23 AM
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Mike S Mike S is offline
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Quote:
Originally Posted by Toobuilder View Post
A little research on "bypass oil filtration" is worth the time. These filters are so fine they will even strip the additives out of the oil (in addition to ALL the trash), but they dont flow enough to keep the bearings alive at full flow. Cant have it both ways.
Bypass filters do not filter the entire flow------that is what a full flow filter does.

Bypass filters take a portion of the flow and filter it, leaving most of the pump output to lube the engine.
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  #84  
Old 09-05-2022, 02:09 PM
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Toobuilder Toobuilder is offline
 
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Yes, exactly my point. They filter very effectively but just "ooze" while doing it. Over time, the crankcase is left with very clean oil, but no, the bearings are not protected if it starts making metal.

Even the best "full flow" filters pass debris large enough to score bearings. Clamp down the micron count (like with a bypass filter) and it wont flow enough to keep the bearings lubricated. Sure the oil will be clean, but not enough volume to keep the bearings afloat.

Like I said, "clean oil" is relative.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
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1940 Taylorcraft BL-65
1984 L39C - SOLD
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  #85  
Old 09-05-2022, 02:21 PM
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Mike S Mike S is offline
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Quote:
Originally Posted by Toobuilder View Post
Clamp down the micron count (like with a bypass filter) and it wont flow enough to keep the bearings lubricated.
Again, the bypass filter is only cleaning a small quantity of the oil being supplied by the pump. This clean oil is returned directly to the oil pan. It is not used as the pressure feed to lube the bearings etc.

The vast majority of the oil pump output is still being used to lube the engine.

Quote:
Originally Posted by Toobuilder View Post
Sure the oil will be clean, but not enough volume to keep the bearings afloat.
That is why we now have full flow oil filters-----they do flow enough to lube the engine.
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Flying as of 12/4/2010

Phase 1 done, 2/4/2011

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"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."

Last edited by Mike S : 09-05-2022 at 02:25 PM.
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  #86  
Old 09-05-2022, 03:42 PM
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DanH DanH is offline
 
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Quote:
Originally Posted by Toobuilder View Post
Even the best "full flow" filters pass debris large enough to score bearings.
What size would that be Mike?

Quote:
Clamp down the micron count (like with a bypass filter) and it wont flow enough to keep the bearings lubricated.
The Wix 51515 I used as an example is rated at 7 to 9 gallons per minute, which on its face is enough to satisfy the Lycomings we use. However, I'll need to get my hands on the appropriate ISO standard to know the viscosity used for the rating. Bet it ain't 50w

Bottom line regarding bypass deltaP is simple. It should open just below the pressure which would crush the element. Otherwise, it should never open.
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Last edited by DanH : 09-05-2022 at 04:06 PM.
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  #87  
Old 09-05-2022, 05:06 PM
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hgerhardt hgerhardt is offline
 
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Quote:
Originally Posted by DanH View Post
....... However, I'll need to get my hands on the appropriate ISO standard to know the viscosity used for the rating. Bet it ain't 50w .....
Exactly. No other engines in general use nowadays use that thick of an oil...except maybe Harleys.

Along that same line of thinking, it makes sense to maximize the filter media area to allow a higher flowrate, and probably less bypassing when oil is cold. All of the filters we typically use on Lycomings come in short and long versions. I've been using the long ones almost exclusively on my RV as there's plenty of room between the engine and firewall. But I have one of those odd Dual-Mag engines which offset the filter to where the RH mag would normally go. If you have enough clearance for the bigger filter, why not use one? They cost the same. (48110 vs 48111)

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  #88  
Old 09-05-2022, 05:50 PM
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BillL BillL is offline
 
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Quote:
Originally Posted by Toobuilder View Post
There is often a lot of discussion concerning the "clogged filter bypass" scenario... How often does this actually occur, and even then, what is the actual realized downside?
The by-pass addresses several scenarios. Cold oil is one, where the engine rpm goes high enough with low temps to yield a high delta-p across the filter. It may only happen a few times in winter under limits of oil and temperatures. If the event collapses the filter media then the aircraft could take off and result in engine failure.

The other is if debris clogs the filter media inflight (possibly engine making metal) it becomes the lessor of evils as the engine needs oil. As we know a few extra minutes or seconds of having engine power could be an airport landing vs a smoking hole.

The filters are industry standards to eliminate failure modes known only to the archives of NTSB and engine manufacturers.

There are reasons for all the capabilities built into the standard filters and supported by the design validation standards.

For example, we could use a filter with lower burst, if we are careful about preheat, and not taking off until a certain temp is reached.
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  #89  
Old 09-08-2022, 07:41 PM
Coryb Coryb is offline
 
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Default I went to the dark side!

Since it's hard to get a filter I decided to install the WIX 51515. I used the nipple from my used Champion filter. I screwed the end of the nipple that was in the old filter into the oil filter adaptor. I used red loctite. My big question is how tight do you screw on the new filter? I saw someone say 3/4 turn after contact like a car. Does that work?
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  #90  
Old 09-08-2022, 07:48 PM
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Mike S Mike S is offline
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Quote:
Originally Posted by Coryb View Post
I saw someone say 3/4 turn after contact like a car. Does that work?
That is how I do it.

Never had an issue with that method.
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Flying as of 12/4/2010

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Sold after 240+ wonderful hours of flight.

"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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