X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Wed, 14 May 2014 07:48:46 -0400 Message-ID: X-Original-Return-Path: Received: from vms173003pub.verizon.net ([206.46.173.3] verified) by logan.com (CommuniGate Pro SMTP 6.0.9e) with ESMTP id 6872017 for lml@lancaironline.net; Tue, 13 May 2014 23:26:10 -0400 Received-SPF: pass receiver=logan.com; client-ip=206.46.173.3; envelope-from=lancair403@verizon.net Received: from self87aab97f5d ([unknown] [71.176.7.83]) by vms173003.mailsrvcs.net (Sun Java(tm) System Messaging Server 7u2-7.02 32bit (built Apr 16 2009)) with ESMTPA id <0N5J00IDOO6DBVC4@vms173003.mailsrvcs.net> for lml@lancaironline.net; Tue, 13 May 2014 22:25:26 -0500 (CDT) X-Original-Message-id: From: "William Rumburg" X-Original-To: "Lancair Mailing List" References: Subject: Re: [LML] Re: Cooler CHTs X-Original-Date: Tue, 13 May 2014 23:25:03 -0400 MIME-version: 1.0 Content-type: multipart/alternative; boundary="----=_NextPart_000_0049_01CF6F02.912F07F0" X-Priority: 3 X-MSMail-priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5931 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 This is a multi-part message in MIME format. ------=_NextPart_000_0049_01CF6F02.912F07F0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Chris - my engine was recently overhauled, having fallen victim to = Lycoming's 'achilles heel' - their longstanding rubbing cam and lifter = design. At 600 hours, I found that the cam and lifters were badly = galled, with copious amounts of metal particles throughout the engine. = Frequent flying, use of oil additives, etc. are simply attempts to stave = off the real problem which is the rubbing cam and lifter design; the = solution is the new roller lifter design. I left about 1/8" clearance between the molded fiberglass seals and the = aft side of the cowl air inlets to allow for relative motion between the = engine and cowl. Not the complete inlet seal that your plenum design = offers, but which shouldn't result in more than a miniscule amount of = air leakage. More importantly, I took action to seal wasteful air = leakage paths which rob cooling air from the all-critical cylinder = heads. Several years ago, I asked Lycoming what the optimal CHT is and = they simply said "the lower, the better". I estimate 320 degrees to be = about the lowest obtainable, considering the size of our air inlets. = That's probably more than sufficient for the long term health of the = engine and attempts to go any lower would unproductively increase = cooling drag.=20 Yes, I'll be glad to measure upper plenum pressures, let me know the = procedure/equipment off list. Respectfully, Bill Rumburg N403WR (Sonic bOOm) =20 ----- Original Message -----=20 From: Chris Zavatson=20 To: Lancair Mailing List=20 Sent: Tuesday, May 13, 2014 7:45 AM Subject: [LML] Re: Cooler CHTs Bill, Is that a new engine? -looks spotless. Scott Krueger was also able to get a really good seal on his baffles. = In fact, he had the highest measured pressure recovery I have seen using = flexible baffle material. You wouldn't happen to have (or be interested = in measuring) some upper plenum pressures for comparison? -forever in = search of cooling system data. How do you interface to the inlets? -any pics of that area? thanks, Chris Zavatson N91CZ 360std www.N91CZ.net ------=_NextPart_000_0049_01CF6F02.912F07F0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Chris - my = engine was recently=20 overhauled, having fallen victim = to Lycoming's 'achilles heel' - their longstanding rubbing cam = and=20 lifter design. At 600 hours, I found that the cam and lifters were = badly=20 galled, with copious amounts of metal particles throughout the=20 engine. Frequent flying, use of oil additives, etc. are simply = attempts to=20 stave off the real problem which is the rubbing cam and lifter design; = the=20 solution is the new roller lifter design.
I left about 1/8" clearance between the = molded=20 fiberglass seals and the aft side of the cowl air inlets to allow for = relative=20 motion between the engine and cowl. Not the complete inlet seal that = your plenum=20 design offers, but which shouldn't result in more than a miniscule = amount of air=20 leakage. More importantly, I took action to seal wasteful air leakage=20 paths which rob cooling air from the all-critical cylinder heads.=20 Several years ago, I = asked Lycoming what the=20 optimal CHT is and they simply said "the lower, the better". I estimate = 320=20 degrees to be about the lowest obtainable, considering the = size of our=20 air inlets. That's probably more than sufficient for the long term = health=20 of the engine and attempts to go any lower would unproductively = increase=20 cooling drag.
Yes, I'll be glad to measure upper = plenum=20 pressures, let me know the procedure/equipment off list.
 
Respectfully,
 
Bill Rumburg
N403WR (Sonic bOOm)
 
----- Original Message -----
From:=20 Chris=20 Zavatson
Sent: Tuesday, May 13, 2014 = 7:45 AM
Subject: [LML] Re: Cooler = CHTs

Bill,
Is=20 that a new engine? -looks spotless. Scott=20 Krueger was also able to get a really good seal on his baffles.  = In fact,=20 he had the highest measured pressure recovery I have seen using = flexible=20 baffle material.  You wouldn't happen to have (or be interested = in=20 measuring) some upper plenum pressures for = comparison?  -forever in=20 search of cooling system data. How do you interface = to the=20 inlets? -any pics of that area? thanks, Chris=20 Zavatson N91CZ 360std www.N91CZ.net ------=_NextPart_000_0049_01CF6F02.912F07F0--