Posted for Bill MacLeod <macinsd@gmail.com>:

> Absolutely agree.  Anything is better than nothing at all.  Even a piece of
> wire screen is better than nothing.  At least it would stop bugs and large
> particles.  Getting finer than that is just a matter of degree and how much
> dirt one wants to keep out of the engine.  There is no question that dirt
> in the engine affects wear.  This relationship shows up very clearly in the
> oil analysis.  I personally just like to minimize wear while not affecting
> performance.  K&N claims additional performance (that we have been unable
> to substantiate with independent testing--and could only be true if the
> cellulose counterpart was undersized) while car owners that do oil analysis
> and have tried the K&N filters do see an increase in silicon (dirt) levels
> and increased wear metals.  How much faster will the engine wear out
> because of using a K&N filter?  I have no idea.  I just know we see the
> additional metals in the oil.
>
> The applications I'm speaking about are street cars, not race cars, and are
> driven in all conditions--rain, sleet, snow, etc. (But, when I was racing
> sports cars, we still raced in the rain.) Interesting point you bring up,
> tho', car filters are usually much more protected from the elements than
> are aircraft filters.  I never thought about that.  If the filter were to
> become blocked, isn't that the purpose of the alternate air door?  I've
> never heard of the "suck" test with a wet filter.  I'll try that out of
> curiosity.  I have flown some pretty hard IFR over the past 40 years in all
> kinds of conditions, singles and twins, extremely heavy rain, snow, icing,
> etc., and have never experienced a blocked air filter.  Guess it could
> happen, though.
>
> On the other hand, and I think there was a recent post here referencing it
> also, I have seen, and heard of additional cases, of K&N filters
> disintegrating and holes appearing in the filter media.  That filter media
> has only one place to go--it gets sucked into the engine.  Not a good thing.
>
>
>
>
> On Fri, Jan 17, 2014 at 12:10 PM, geslnelson@sbcglobal.net <
> geslnelson@sbcglobal.net> wrote:
>
>> Can we agree that a K&N filter is better than no filter at all?  Of this,
>> I am sure because each time I have cleaned or replaced my K&N, it has been
>> noticeably dirty.
>>
>> Opinions usually vary - and mine does as to the use of K&N filters in our
>> often-IFR-used airplanes.  I use the K&N filter despite the reasons cited
>> by previous writers on this topic.  My use of K&N filters is because they
>> pass the "suck" test while paper filters fail this test (I have not
>> exhaustively tested  automotive paper filters).
>>
>> In the mid 1990's, I remember reading of a light aircraft that crashed
>> because it had ingested its own wet air filter; yes it was a cellulose-type
>> automotive filter.  (Sorry, I don't have references to this article or
>> event.)  Still building my LNC2 at that time, I elected to do my own suck
>> test - and I recommend that you too do a suck test on your aircraft filters.
>>
>> Conduct the suck test by cutting out a piece of old paper filter
>> (automotive) and then wet part of it by dipping it in water.  The other
>> half should be kept dry.  Now, suck on the dry part and you will find that
>> breathing is easy.  Next, suck on the wet part and you will find yourself
>> turning blue for lack of oxygen.
>>
>> Repeat the suck test on a K&N filter and you will note that breathing is
>> easy whether wet or dry because the filter is oiled.
>>
>> I was satisfied that a wet paper filter could, indeed, cause power loss on
>> an aircraft engine - especially because our IFR aircraft must necessarily
>> advance into clouds, rain, ice and snow without the slightest power
>> hesitation or interruption - unlike racing automobiles that wisely avoid
>> rain, ice and snow.
>>
>> My shoulders are broad and my loins are girded; I can take the slings and
>> arrows that are sure to come.  In the words of Bill O'Reilly, "Am I wrong?"
>>