Return-Path: Sender: "Marvin Kaye" To: lml@lancaironline.net Date: Tue, 25 Jan 2005 11:24:36 -0500 Message-ID: X-Original-Return-Path: Received: from systems3.net ([68.14.236.16] verified) by logan.com (CommuniGate Pro SMTP 4.2.8) with ESMTP-TLS id 621125 for lml@lancaironline.net; Tue, 25 Jan 2005 11:22:25 -0500 Received-SPF: none receiver=logan.com; client-ip=68.14.236.16; envelope-from=cberland@systems3.net Received: from systems0d3b724 ([192.168.1.81]) by systems3.net (8.13.1/8.13.1/Debian-12) with SMTP id j0PGLrwF013856 for ; Tue, 25 Jan 2005 09:21:53 -0700 X-Original-Message-ID: <00c901c502f9$428cc080$5101a8c0@systems0d3b724> From: "Craig Berland" X-Original-To: "Lancair Mail List" Subject: [LML] Re: Plugs and Mags for IVP X-Original-Date: Tue, 25 Jan 2005 09:16:38 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_00C6_01C502BE.932E3D10" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1437 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1441 X-Virus-Scanned: clamd / ClamAV version 0.75-1, clamav-milter version 0.75c on linux X-Virus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_00C6_01C502BE.932E3D10 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Doug wrote "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)." Walter wrote: " 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." Walter, I tend to believe you are correct, the improvement was more air = temp related, however, don't diminish the effects of a good ignition = system. Poor plugs, bad wires, worn out mag (even hotter spark) all can = make a significant affect for the same reason the RPM drops on one mag = vs both. If the flame is lit but the flame kernel is "poor" the cylinder = will make power but not as much as if the flame kernel is "good". The = idea is to have as fast of combustion as possible without it being an = explosion (non controlled combustion). With 2 flame fronts (two spark = plugs per cylinder) the combustion time is greatly reduced and therefore = power is increased and BSFC is reduced (fuel economy is improved). = Particularly on our big bore aircraft engines. Just changing your fuel = from 100 octane to 130 octane will reduce power and fuel economy for two = reasons. 1. The 130 octane fuel has less BTU's per gallon. 2. The 130 = octane fuel burns slower. Some of this loss came be regained by = advancing the ignition timing when running higher octane fuel. Craig Berland ------=_NextPart_000_00C6_01C502BE.932E3D10 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Doug wrote
"Of interest, within the limits of my setup (VM1000, = all=20 altitude and engine parameters the same with the exception of a 15degF = cooler=20 OAT) I did notice a 20-30degF cooler CHT with the new Iridium plugs over = a broad=20 range of fuel flows, and a 2-3 knot improved speed at lean-of-peak = operations=20 (no change at ROP operations)."
Walter wrote:
" I know of no scientific reason that the type of plug making = the=20 spark could make such differences. It's more likely the OAT. More O2 = molecules=20 for combustion and better air cooling."
 
Walter, I tend to believe you are = correct, the=20 improvement was more air temp related, however, don't diminish the = effects of a=20 good ignition system. Poor plugs, bad wires, worn out mag = (even hotter=20 spark) all can make a significant affect for the same reason the RPM = drops on=20 one mag vs both. If the flame is lit but the flame kernel is "poor" the = cylinder=20 will make power but not as much as if the flame kernel is "good". The = idea is to=20 have as fast of combustion as possible without it being an explosion = (non=20 controlled combustion). With 2 flame fronts (two spark plugs per = cylinder) the=20 combustion time is greatly reduced and therefore power is increased and = BSFC is=20 reduced (fuel economy is improved). Particularly on our big bore = aircraft=20 engines. Just changing your fuel from 100 octane to 130 octane will = reduce power=20 and fuel economy for two reasons. 1. The 130 octane fuel has less BTU's = per=20 gallon. 2. The 130 octane fuel burns slower. Some of this loss came be = regained=20 by advancing the ignition timing when running higher octane = fuel.
 
Craig Berland

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