Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Tue, 25 Jan 2005 23:07:49 -0500 Message-ID: X-Original-Return-Path: Received: from imf16aec.mail.bellsouth.net ([205.152.59.64] verified) by logan.com (CommuniGate Pro SMTP 4.2.8) with ESMTP id 622359 for lml@lancaironline.net; Tue, 25 Jan 2005 22:29:07 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.152.59.64; envelope-from=Lancair1@bellsouth.net Received: from P4DESKTOP ([66.157.206.9]) by imf16aec.mail.bellsouth.net (InterMail vM.5.01.06.11 201-253-122-130-111-20040605) with ESMTP id <20050126032837.YZII1983.imf16aec.mail.bellsouth.net@P4DESKTOP> for ; Tue, 25 Jan 2005 22:28:37 -0500 From: "Douglas W. Johnson, MD" X-Original-To: "'Lancair Mailing List'" Subject: RE: [LML] Re: Plugs and Mags for IVP X-Original-Date: Tue, 25 Jan 2005 22:29:49 -0500 X-Original-Message-ID: <01ed01c50357$4b1e1d30$0f01a8c0@P4DESKTOP> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_01EE_01C5032D.62481530" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook CWS, Build 9.0.2416 (9.0.2910.0) Importance: Normal X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1441 In-Reply-To: This is a multi-part message in MIME format. ------=_NextPart_000_01EE_01C5032D.62481530 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit I certainly bow to greater authority on this. Although I suspected OAT diff might have accounted for this, I talked to a Unison insider who suggested something about better flame propagation with thier Iridium plugs, and therefore more efficient burn of fuel in the cylinder. Would have suspected this would have raised the CHT's, however, if that were the case.... Doug -----Original Message----- From: Lancair Mailing List [mailto:lml@lancaironline.net]On Behalf Of Walter Atkinson Sent: Tuesday, January 25, 2005 10:06 AM To: Lancair Mailing List Subject: [LML] Re: Plugs and Mags for IVP Doug: **Of interest, within the limits of my setup (VM1000, all altitude and engine parameters the same with the exception of a 15degF cooler OAT) I did notice a 20-30degF cooler CHT with the new Iridium plugs over a broad range of fuel flows, and a 2-3 knot improved speed at lean-of-peak operations (no change at ROP operations).** I know of no scientific reason that the type of plug making the spark could make such differences. It's more likely the OAT. More O2 molecules for combustion and better air cooling. The improved LOP speed is O2 increases in the cooler air. It allows for more FF at a given LOP setting. If you were to set the same FF, the HP output and TAS would be the same. We must be careful to assign the correct cause for an observed change. Walter ------=_NextPart_000_01EE_01C5032D.62481530 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable
I=20 certainly bow to greater authority on this.  Although I suspected = OAT diff=20 might have accounted for this, I talked to a Unison insider who = suggested=20 something about better flame propagation with thier Iridium plugs, and = therefore=20 more efficient burn of fuel in the cylinder.  Would have suspected = this=20 would have raised the CHT's, however, if that were the=20 case....
Doug
-----Original Message-----
From: Lancair Mailing = List=20 [mailto:lml@lancaironline.net]On Behalf Of Walter=20 Atkinson
Sent: Tuesday, January 25, 2005 10:06 = AM
To:=20 Lancair Mailing List
Subject: [LML] Re: Plugs and Mags for=20 IVP

Doug:

**Of=20 interest, within the limits of my setup (VM1000, all altitude and = engine=20 parameters the same with the exception of a 15degF cooler OAT) I did = notice a=20 20-30degF cooler CHT with the new Iridium plugs over a broad range of = fuel=20 flows, and a 2-3 knot improved speed at lean-of-peak operations (no = change at=20 ROP operations).**


I know of = no=20 scientific reason that the type of plug making the spark could make = such=20 differences. It's more likely the OAT. More O2 molecules for = combustion and=20 better air cooling. The improved LOP speed is O2 increases in the = cooler air.=20 It allows for more FF at a given LOP setting. If you were to set the = same FF,=20 the HP output and TAS would be the same. We must be careful to assign = the=20 correct cause for an observed = change.

Walter
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