X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 17 Jan 2012 11:41:36 -0500 Message-ID: X-Original-Return-Path: Received: from nschwmtas04p.mx.bigpond.com ([61.9.189.146] verified) by logan.com (CommuniGate Pro SMTP 5.4.3) with ESMTP id 5352688 for lml@lancaironline.net; Mon, 16 Jan 2012 19:57:54 -0500 Received-SPF: pass receiver=logan.com; client-ip=61.9.189.146; envelope-from=frederickmoreno@bigpond.com Received: from nschwcmgw06p ([61.9.190.166]) by nschwmtas04p.mx.bigpond.com with ESMTP id <20120117005718.OHGS2025.nschwmtas04p.mx.bigpond.com@nschwcmgw06p> for ; Tue, 17 Jan 2012 00:57:18 +0000 Received: from Razzle ([58.165.11.246]) by nschwcmgw06p with BigPond Outbound id NQx81i00F5JWv5W01QxFT5; Tue, 17 Jan 2012 00:57:18 +0000 X-Authority-Analysis: v=2.0 cv=asYw+FlV c=1 sm=1 a=Ap2HPOVkqcVN/0SrKbfd8g==:17 a=JDadKst33uMA:10 a=8nJEP1OIZ-IA:10 a=ae0nFCQH0cYgfGLZUc8A:9 a=wPNLvfGTeEIA:10 a=DBx65n6SlrhKevMho10A:9 a=PCKTupa23b7oTXRaZ5sA:7 a=Ap2HPOVkqcVN/0SrKbfd8g==:117 MIME-Version: 1.0 X-Original-Message-Id: <4F14C759.00001E.03988@RAZZLE> X-Original-Date: Tue, 17 Jan 2012 08:56:57 +0800 Content-Type: Multipart/Alternative; charset="iso-8859-1"; boundary="------------Boundary-00=_XY3XP4J1VA4000000000" X-Mailer: IncrediMail (6244788) From: "Frederick Moreno" X-FID: FLAVOR00-NONE-0000-0000-000000000000 X-Priority: 3 X-Original-To: "Lancair Mail (lml@lancaironline.net)" Subject: Fw: Re: Ceramic exhaust coatings --------------Boundary-00=_XY3XP4J1VA4000000000 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable =0D =2E=0D =0D "But there hasn't been much posted on the subject of interior heat coatin= gs for the exhaust system." =0D =0D Can't hurt, reduces the heat flow to the metal slightly, but only slightl= y.=20 Too thin and has too high a thermal conductivity to help much. But if = it makes you feel good. Leave the outside surface alone and let it turn its natural black. When the exhaust manifold has reached the end of its life due to thinning of walls extensive cracking, or creep (see picture posted= by Brent), replace it. Think of exhaust manifolds like oil filters. Plan o= n regular replacement depending on the operating regime. More demanding (s= uch as turboappliction), shorter replacement interval. =0D =0D Don't even think about Inconel (very high temp alloy) exhaust headers. N= ot worth it. =0D =0D "I might go with a mild steel system if I were to do it again."=0D =0D Don't do it. It will droop off due to gravity having absolutely no creep strength, and will drop in a heap in a few hours. And it will rust to du= st in a few cycles. That is why stainless steel is used - because of its higher strength at elevated temperatures and because of its corrosion resistance under the same conditions. Mild steel has no capability in th= is operating regime. =0D Fred=0D =0D I=20 --------------Boundary-00=_XY3XP4J1VA4000000000 Content-Type: Text/HTML; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

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"But there hasn't been much posted on the subject of interior heat c= oatings for the exhaust system."

Can't hurt, reduces the heat flow to the metal slightly, but only sl= ightly. Too thin and has too high a thermal conductivity to&n= bsp; help much. But if it makes you feel good. Leave the outs= ide surface alone and let it turn its natural black. When the exhau= st manifold has reached the end of its life due to thinning of walls exte= nsive cracking, or creep (see picture posted by Brent), replace it. = Think of exhaust manifolds like oil filters. Plan on regular repla= cement depending on the operating regime. More demanding (such as t= urboappliction), shorter replacement interval.

Don't even think about Inconel (very high temp alloy) exhaust header= s. Not worth it.

"I might go with a mild steel system if I were to do it again."

Don't do it. It will droop off due to gravity having abso= lutely no creep strength, and will drop in a heap in a few hours. A= nd it will rust to dust in a few cycles. That is why stainless stee= l is used - because of its higher strength at elevated temperatures and b= ecause of its corrosion resistance under the same conditions. Mild = steel has no capability in this operating regime.

Fred

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