X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 18 Jan 2014 19:30:05 -0500 Message-ID: X-Original-Return-Path: Received: from mail-qa0-f54.google.com ([209.85.216.54] verified) by logan.com (CommuniGate Pro SMTP 6.0.8) with ESMTPS id 6693104 for lml@lancaironline.net; Sat, 18 Jan 2014 18:12:50 -0500 Received-SPF: pass receiver=logan.com; client-ip=209.85.216.54; envelope-from=macinsd@gmail.com Received: by mail-qa0-f54.google.com with SMTP id i13so4536306qae.27 for ; Sat, 18 Jan 2014 15:12:14 -0800 (PST) MIME-Version: 1.0 X-Received: by 10.224.113.204 with SMTP id b12mr15521496qaq.35.1390086734186; Sat, 18 Jan 2014 15:12:14 -0800 (PST) Received: by 10.97.1.202 with HTTP; Sat, 18 Jan 2014 15:12:14 -0800 (PST) In-Reply-To: References: X-Original-Date: Sat, 18 Jan 2014 15:12:14 -0800 X-Original-Message-ID: Subject: Re: [LML] Re: K&N Filter From: Bill MacLeod X-Original-To: Lancair Mailing List Content-Type: multipart/alternative; boundary=047d7bea3e20ffabab04f046c924 --047d7bea3e20ffabab04f046c924 Content-Type: text/plain; charset=ISO-8859-1 Gary, Good points, and address something I wasn't considering. The TSIO 550 engine in my L IV has twin turbos and is never lacking for manifold pressure. It only operates at full power (Wide Open Throttle-WOT) for very brief periods at take-off. Those with naturally aspirated engines are more concerned with any intake restriction as it would reduce available power as their altitude increases, of course. So, I see the concern. But, if the filter is sized properly, there should be an almost immeasurable, insignificant reduction in airflow/pressure to the intake. Granted, that's a big "if" considering the tight confines of aircraft cowlings. I come back to: try different filters and determine if there is a noticeable change in manifold pressure. Testing is the only way to know for sure, all else is just speculation. Bill On Sat, Jan 18, 2014 at 11:42 AM, Gary Casey wrote: > Lots of comments on this subject and I agree with most. Just a few > "clarifications." First, the restriction of an air filter is there all > time the throttle is wide open, including at high altitude. True, a high > altitude the number of hp lost is less, but the percent loss is about the > same. Another comment said that there isn't a noticeable drop in manifold > pressure, so it doesn't make any difference. True, the reduction in > manifold pressure isn't much, but it is there. So while every little bit > counts, it is up to the owner to decide whether the reduced pressure drop > in the K&N is worth the potential increased wear. > > Also, it isn't exactly true that IFR aircraft must not have "the slightest > power hesitation...." In fact, air filters can and do plug with ice and > water. The FAA concluded that since it is unavoidable, they require an > alternate air source, either automatic or manually operated. > > Okay, you can soak a paper filter with water and it will block air flow, > while if you do the same thing with a K&N it will still flow. That's > partly because the holes in the filter are larger (that would be the same > holes that let the dust through) and partly because the oil repels water. > Is that a big enough advantage to use the K&N? Don't know. A filter > manufacturer told me that the main difference between automotive and > aircraft filters is that aircraft filters are required to have enough > strength to avoid being sucked into the engine if they get plugged. That's > why there is a metal screen on the downstream side. > For what it's worth, > Gary Casey > > If you occasionally take off when you can see dust in the air, you might > be well advised to use a paper filter. > 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&nbs= > p;wisely avoid rain, ice and snow. > --047d7bea3e20ffabab04f046c924 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
Gary,

Good points, and address somethin= g I wasn't considering. =A0The TSIO 550 engine in my L IV has twin turb= os and is never lacking for manifold pressure. =A0It only operates at full = power (Wide Open Throttle-WOT) for very brief periods at take-off. =A0Those= with naturally aspirated engines are more concerned with any intake restri= ction as it would reduce available power as their altitude increases, of co= urse. =A0So, I see the concern. =A0But, if the filter is sized properly, th= ere should be an almost immeasurable, insignificant reduction in airflow/pr= essure to the intake. =A0Granted, that's a big "if" consideri= ng the tight confines of aircraft cowlings. =A0I come back to: =A0try diffe= rent filters and determine if there is a noticeable change in manifold pres= sure. =A0Testing is the only way to know for sure, all else is just specula= tion.

Bill=A0


<= div class=3D"gmail_quote">On Sat, Jan 18, 2014 at 11:42 AM, Gary Casey <casey.gary@yahoo.com> wrote:
Lots of comments on this subject and I agree with most. =A0Just a few "= ;clarifications." =A0First, the restriction of an air filter is there = all time the throttle is wide open, including at high altitude. =A0True, a = high altitude the number of hp lost is less, but the percent loss is about = the same. =A0Another comment said that there isn't a noticeable drop in= manifold pressure, so it doesn't make any difference. =A0True, the red= uction in manifold pressure isn't much, but it is there. =A0So while ev= ery little bit counts, it is up to the owner to decide whether the reduced = pressure drop in the K&N is worth the potential increased wear.

Also, it isn't exactly true= that IFR aircraft must not have "the slightest power hesitation....&q= uot; =A0In fact, air filters can and do plug with ice and water. =A0The FAA= concluded that since it is unavoidable, they require an alternate air sour= ce, either automatic or manually operated.

Okay, you can soak a paper filter with water and it will block air flow, wh= ile if you do the same thing with a K&N it will still flow. =A0That'= ;s partly because the holes in the filter are larger (that would be the same holes that let the dust through)= and partly because the oil repels water. =A0Is that a big enough advantage= to use the K&N? =A0Don't know. =A0A filter manufacturer told me th= at the main difference between automotive and aircraft filters is that airc= raft filters are required to have enough strength to avoid being sucked int= o the engine if they get plugged. =A0That's why there is a metal screen= on the downstream side.
For what it's worth,
Gary Casey

If you occasionally take off when you can see dust in the air, you might be= well advised to use a paper filter.=A0
I was satisfied that a wet paper filter could, indeed, cause power loss = on=3D
an aircraft engine - especially because our IFR aircraft must nece= ssarily =3D
advance into clouds, rain, ice and snow without&nbsp;the slightest
power hesitation or interruptio= n&nbsp;- unlike racing automobiles that&nbs=3D
p;wisely avoid ra= in, ice and snow.

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