X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 08 Feb 2009 14:23:40 -0500 Message-ID: X-Original-Return-Path: Received: from elasmtp-curtail.atl.sa.earthlink.net ([209.86.89.64] verified) by logan.com (CommuniGate Pro SMTP 5.2.12) with ESMTP id 3480707 for lml@lancaironline.net; Fri, 06 Feb 2009 20:31:12 -0500 Received-SPF: none receiver=logan.com; client-ip=209.86.89.64; envelope-from=colyncase@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=Vr46kdW3STDUczA/V+i/lKSHQqoEJrzRvdglvOrRGjcnYQT14vR8XiBjOGdh87cf; h=Received:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE:X-ELNK-Trace:X-Originating-IP; Received: from [216.57.118.63] (helo=ccaselt3) by elasmtp-curtail.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1LVc1l-0000yi-6l for lml@lancaironline.net; Fri, 06 Feb 2009 20:30:37 -0500 X-Original-Message-ID: <272c01c988c3$adc15a60$b98c020a@nvidia.com> From: "Colyn Case at earthlink" X-Original-To: "Lancair Mailing List" References: Subject: Re: [LML] Re: cylinder wear-to lean or not too lean X-Original-Date: Fri, 6 Feb 2009 20:30:36 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_2729_01C98899.C4683FB0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 X-ELNK-Trace: 63d5d3452847f8b1d6dd28457998182d7e972de0d01da940c044aa0a158306604bbc00db6fa0739b350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 216.57.118.63 This is a multi-part message in MIME format. ------=_NextPart_000_2729_01C98899.C4683FB0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable John, Did they really print that about CHT? I don't remember that max CHT equates to anything useful although it = may correlate very well to max internal cylinder pressure (ICP), which = is a bad thing. ...but it's also affected by cylinder cooling, while = EGT is (mostly) not. Max EGT would be stoichiometric which is most = efficient if your engine can take it. Usually slightly rich of that = (e.g. 50 dF ROP) is better power but also involves more pressure before = top dead center and is close to max ICP. There's a really scary picture you get early in the APS course which = shows how the internal cylinder pressure varies in relation to crank = position when you are running at "best power". A measurable amount of = the combustion expansion is actually pushing backwards on the crank = until it comes over the top. Great for torsional stress. Colyn ------=_NextPart_000_2729_01C98899.C4683FB0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

John,

Did they really = print that about=20 CHT?

I don't remember = that max CHT=20 equates to anything useful although it may correlate very well to max = internal=20 cylinder pressure (ICP), which is a bad thing. ...but it's also = affected=20 by cylinder cooling, while EGT is (mostly) not. Max EGT would be = stoichiometric=20 which is most efficient if your engine can take it. Usually = slightly=20 rich of that (e.g. 50 dF ROP) is better power but also involves more = pressure=20 before top dead center and is close to max ICP.

There's a really = scary picture=20 you get early in the APS course which shows how the internal cylinder = pressure=20 varies in relation to crank position when you are running at "best = power". =20 A measurable amount of the combustion expansion is actually pushing = backwards on=20 the crank until it comes over the top. Great for torsional=20 stress.

Colyn

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