X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 11 Feb 2009 13:02:41 -0500 Message-ID: X-Original-Return-Path: Received: from vms173019pub.verizon.net ([206.46.173.19] verified) by logan.com (CommuniGate Pro SMTP 5.2.12) with ESMTP id 3487261 for lml@lancaironline.net; Wed, 11 Feb 2009 01:23:05 -0500 Received-SPF: pass receiver=logan.com; client-ip=206.46.173.19; envelope-from=tom.gourley@verizon.net Received: from jacky0da39824a ([71.111.132.126]) by vms173019.mailsrvcs.net (Sun Java(tm) System Messaging Server 6.3-7.04 (built Sep 26 2008; 32bit)) with ESMTPA id <0KEW00LXT1OW8BH1@vms173019.mailsrvcs.net> for lml@lancaironline.net; Wed, 11 Feb 2009 00:22:10 -0600 (CST) X-Original-Message-id: Reply-to: "Tom Gourley" From: "Tom Gourley" X-Original-To: "Lancair Mailing List" References: Subject: Re: [LML] Re: cylinder wear-to lean or not too lean X-Original-Date: Tue, 10 Feb 2009 22:22:01 -0800 MIME-version: 1.0 Content-type: multipart/alternative; boundary="----=_NextPart_000_0077_01C98BCD.FEA0D700" X-Priority: 3 X-MSMail-priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5512 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 X-Antivirus: avast! (VPS 090210-0, 02/10/2009), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_0077_01C98BCD.FEA0D700 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable In the "for what it's worth" category a very experienced engine = rebuilder told me some years back that he had seen a change in cylinder = wear patterns over the last few decades. In his opinion using the = accepted leaning technique of the 60's and early 70's, i.e. 50 degrees = ROP, was resulting in more and earlier cylinder wear when that technique = was used in the 90's. He said that now (which was about 10 years ago) = it was necessary to run closer to 150 degrees ROP when running 70 - 75% = power. (Running LOP wasn't common at this time.) His hypothesis was = that this was the result of changes in our fuels. I have seen no data = to support or refute this hypothesis, but it can make for some = interesting hangar discussions the next time you're hanging out at the = airport and weather is below minimums. Tom Gourley ------=_NextPart_000_0077_01C98BCD.FEA0D700 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
In the "for what it's worth" category a = very=20 experienced engine rebuilder told me some years back that he had seen a = change=20 in cylinder wear patterns over the last few decades.  In his = opinion using=20 the accepted leaning technique of the 60's and early = 70's, i.e.=20 50 degrees ROP, was resulting in more and earlier cylinder wear = when that=20 technique was used in the 90's.  He said that now (which was about = 10 years=20 ago) it was necessary to run closer to 150 degrees ROP when running 70 - = 75%=20 power.  (Running LOP wasn't common at this time.)  His = hypothesis was=20 that this was the result of changes in our fuels.  I have seen no = data to=20 support or refute this hypothesis, but it can make for some interesting = hangar=20 discussions the next time you're hanging out at the airport and weather = is below=20 minimums.
 
Tom Gourley
 
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