X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 29 Dec 2005 22:01:08 -0500 Message-ID: X-Original-Return-Path: <5zq@cox.net> Received: from eastrmmtao04.cox.net ([68.230.240.35] verified) by logan.com (CommuniGate Pro SMTP 5.0.5) with ESMTP id 905296 for lml@lancaironline.net; Thu, 29 Dec 2005 12:47:51 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.240.35; envelope-from=5zq@cox.net Received: from OFFICE ([68.110.252.196]) by eastrmmtao04.cox.net (InterMail vM.6.01.05.02 201-2131-123-102-20050715) with SMTP id <20051229174342.ISSA19943.eastrmmtao04.cox.net@OFFICE> for ; Thu, 29 Dec 2005 12:43:42 -0500 X-Original-Message-ID: <03e201c60c9f$cf10dcc0$6501a8c0@OFFICE> From: "Bill&Sue" <5zq@cox.net> X-Original-To: "Lancair Mailing List" References: Subject: Where has all the power gone? X-Original-Date: Thu, 29 Dec 2005 12:46:33 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_03DF_01C60C75.E6019C50" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_03DF_01C60C75.E6019C50 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Dumb question for you smart guys. I've been reading all of the spark timing information with great = interest. We have a while before we have to settle on an ignition system = for our non TC 550 and, of course, would like to make the most informed = decision. Soooo, George, Scott, Hamid, Paul, Rick, et al, how about = this: Seems to me that rpm changes effectively adjust ignition timing. For = example, if you're running at 2500 rpm and the spark occurs at 25 btc, = the flame propagates at a rate that produces max pressure at some point = after tdc, lets just say 15 degrees. If you reduced the rpm to 2200 and = the spark occurred at 25 btc the flame would propagate at the same rate = as before but the piston is moving slower. Seems to me that the max = pressure would occur at somewhere less than 15 after tdc, effectively = advancing the ignition.=20 Most agree that the majority of the advantage of adjusting spark timing = happens at lower power settings. To me, it looks like the advantage is = better fuel economy as opposed to more power. Couldn't one simply pull = the prop control back to gain this same advantage? Probably lots of flaws in my thinking, but I'm not smart enough to see = 'em. Help me out. Bill Harrelson 5zq@cox.net N5ZQ 320 1,100+ hrs N6ZQ IV 4.239% =20 ------=_NextPart_000_03DF_01C60C75.E6019C50 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Dumb question for you smart = guys.
 
I've been reading all of the spark = timing=20 information with great interest. We have a while before we have to = settle on an=20 ignition system for our non TC 550 and, of course, would like to make = the most=20 informed decision. Soooo, George, Scott, Hamid, Paul, Rick, et al, how = about=20 this:
 
Seems to me that rpm changes=20 effectively adjust ignition timing. For example, if you're running = at 2500=20 rpm and the spark occurs at 25 btc, the flame propagates at a rate that = produces=20 max pressure at some point after tdc, lets just say 15 degrees. If you = reduced=20 the rpm to 2200 and the spark occurred at 25 btc the flame would = propagate at=20 the same rate as before but the piston is moving slower. Seems to me = that the=20 max pressure would occur at somewhere less than 15 after tdc, = effectively=20 advancing the ignition.
 
Most agree that the majority of the = advantage of=20 adjusting spark timing happens at lower power settings. To me, it = looks=20 like the advantage is better fuel economy as opposed to more power. = Couldn't one=20 simply pull the prop control back to gain this same = advantage?
 
Probably lots of flaws in my thinking, = but I'm not=20 smart enough to see 'em. Help me out.
 
Bill Harrelson
5zq@cox.net
N5ZQ 320 1,100+ hrs
N6ZQ  IV  4.239%
 
 
 
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