X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 08 Aug 2005 16:55:05 -0400 Message-ID: X-Original-Return-Path: Received: from imo-m28.mx.aol.com ([64.12.137.9] verified) by logan.com (CommuniGate Pro SMTP 4.3.7) with ESMTP id 641758 for lml@lancaironline.net; Mon, 08 Aug 2005 16:53:10 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.9; envelope-from=Sky2high@aol.com Received: from Sky2high@aol.com by imo-m28.mx.aol.com (mail_out_v38_r4.1.) id q.cf.2e632b30 (4320) for ; Mon, 8 Aug 2005 16:52:15 -0400 (EDT) From: Sky2high@aol.com X-Original-Message-ID: X-Original-Date: Mon, 8 Aug 2005 16:52:15 EDT Subject: Re: [LML] Ram Air Flowback X-Original-To: lml@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="-----------------------------1123534335" X-Mailer: 9.0 Security Edition for Windows sub 5009 X-Spam-Flag: NO -------------------------------1123534335 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 8/8/2005 12:49:25 P.M. Central Standard Time, bakercdb@gmail.com writes: I have the Airflow Performance ram air valve on my Lycoming IO360. This valve does not close off the filter when ram air is selected. I have wondered how much ram air pressure I was losing back through the air filter (and believe this has been debated on the LML). According to the following test by an RV builder, with a similar installation to mine, there is no loss. See the attached RV link and a photo of my installation. Clark, 1. MAP is a measure of the smoothed average absolute pressure in the induction system typically as taken from a primer port in the cylinder head. Valve clatter notwithstanding. Air is being drawn out of this system by that air pump known as the engine. 2. A well constructed cowling with a well sealed engine baffling system is itself a ram air chamber with air being drawn off by the engine cooling function and, perhaps, by the oil cooler and induction system, too. For example, we expect to see 5+ inches of water as a minimal pressure difference between the upper and lower cowl for reasonable engine cooling. (5.4" H2O = .4" Hg = .2 psi). 3. A fair ram air system with an opening back to the upper cowl might indeed see only a small rise if the upper cowl is closed off because when open, the upper cowl air pressure may be significant, thus preventing serious loss of pressure. However, .4 "Hg MAP loss is approximately 1.5% loss of possible engine power. 4. The recent discussion was about a filter open to the lower cowl with the combined effect of higher induction air temperature and even lower "back pressure." on the filter - yet is seemed not to have much of a loss in MAP. 5. Some of us have the cowl positioned landing light and do not have room for a large air duct, let alone a filter box in that area. It would be interesting if you could do some reporting on the performance of your system - assuming duct ape can really seal off the upper cowl. Scott Krueger AKA Grayhawk Lancair N92EX IO320 SB 89/96 Aurora, IL (KARR) -------------------------------1123534335 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable
In a message dated 8/8/2005 12:49:25 P.M. Central Standard Time,=20 bakercdb@gmail.com writes:
<= FONT=20 style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size= =3D2>I have=20 the Airflow Performance ram air valve on my Lycoming IO360.
This valve= =20 does not close off the filter when ram air is selected.  I
have=20 wondered how much ram air pressure I was losing back through the
air fi= lter=20 (and believe this has been debated on the LML).  According
to the=20 following test by an RV builder, with a similar installation to
mine, t= here=20 is no loss.  See the attached RV link and a photo of=20 my
installation.
Clark,
 
1. MAP is a measure of the smoothed average absolute pressure in the=20 induction system typically as taken from a primer port in the cylinder=20 head.  Valve clatter notwithstanding.  Air is being drawn out of t= his=20 system by that air pump known as the engine.
 
2. A well constructed cowling with a well sealed engine baffling system= is=20 itself a ram air chamber with air being drawn off by the engine cooling func= tion=20 and, perhaps, by the oil cooler and induction system, too.  For example= , we=20 expect to see 5+ inches of water as a minimal pressure difference between th= e=20 upper and lower cowl for reasonable engine cooling. (5.4" H2O =3D .4" Hg=20= =3D .2=20 psi).
 
3. A fair ram air system with an opening back to the upper cowl might=20 indeed see only a small rise if the  upper cowl is closed off because w= hen=20 open, the upper cowl air pressure may be significant, thus preventing seriou= s=20 loss of pressure.  However, .4 "Hg MAP loss is approximately 1.5% loss=20= of=20 possible engine power.
 
4.  The recent discussion was about a filter open to the lower cow= l=20 with the combined effect of higher induction air temperature and even lower=20 "back pressure." on the filter - yet is seemed not to have much of a loss in= =20 MAP.
 
5.  Some of us have the cowl positioned landing light and do not h= ave=20 room for a large air duct, let alone a filter box in that area.
 
It would be interesting if you could do some reporting on the performan= ce=20 of your system - assuming duct ape can really seal off the upper cowl.
 
 
 
 
 
Scott Krueger=20 AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL=20 (KARR)



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