X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 12 Jan 2012 15:41:35 -0500 Message-ID: X-Original-Return-Path: Received: from elasmtp-galgo.atl.sa.earthlink.net ([209.86.89.61] verified) by logan.com (CommuniGate Pro SMTP 5.4.3) with ESMTP id 5347561 for lml@lancaironline.net; Thu, 12 Jan 2012 10:08:33 -0500 Received-SPF: none receiver=logan.com; client-ip=209.86.89.61; envelope-from=colyncase@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=GNTBRW24LZ0GE44HOo1Bjd7aL1dDa7CNqPYoF7vH6hvhquFpoiX6/EWoDAuqPhvU; h=Received:From:Mime-Version:Content-Type:Subject:Date:In-Reply-To:To:References:Message-Id:X-Mailer:X-ELNK-Trace:X-Originating-IP; Received: from [72.73.82.72] (helo=[192.168.1.24]) by elasmtp-galgo.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1RlMFz-0006Gk-Dy for lml@lancaironline.net; Thu, 12 Jan 2012 10:07:59 -0500 From: Colyn Case Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: multipart/alternative; boundary=Apple-Mail-44-181327765 Subject: Re: [LML] Re: Ceramic exhaust coatings X-Original-Date: Thu, 12 Jan 2012 10:07:58 -0500 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: <8EE2D949-23DC-48A4-ACCF-D22ED8F12E61@earthlink.net> X-Mailer: Apple Mail (2.1084) X-ELNK-Trace: 63d5d3452847f8b1d6dd28457998182d7e972de0d01da940c5b1f193322ea2e486d27f217ba6d543350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 72.73.82.72 --Apple-Mail-44-181327765 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii I think it is about radiation. The reason I did it was to reduce the = amount of heat radiated back at the cylinder heads. While a shiny = reflector might be more effective in theory, installing it everywhere = you would want it on a TSIO550 exhaust system is a lot of work. =20 On Jan 12, 2012, at 8:46 AM, Gary Casey wrote: I guess I'm just not convinced about the effectiveness of typical = ceramic coatings. =46rom what I can find out they are typically .001 to = .002 thick, about 5% of the thickness of the metal. In order to = significantly reduce the heat transfer compared to the metal, they would = have to have thermal conductivity in that order compared to steel. I = can't find out what material is used, but some might use zirconia, a = very good insulator, which has about 10 to 20% of the conductivity of = steel. But that's not the whole story. Inside the pipe is a gas at = perhaps 1500F moving at a relatively high velocity. The conductivity to = the metal is therefore relatively good, resulting in a metal temperature = of probably 1200F. The air on the outside is at about 180F and it is = moving slowly, so the heat transfer from the pipe to the air is "poor." = My guess is that the surface temperature of the ceramic is going to be = very close to what the metal would be without the coating. There just = isn't enough thickness for it to be well insulated. Swain Technologies = has a proprietary process that puts .015 thickness on metal and that = would probably work. A big factor in heat transfer is radiation and the = best way to reduce that is with a shiny metal surface spaced away from = the exhaust pipe, or from the device to be protected. Maybe ceramic coatings work well, but I'm afraid I'm not convinced. Gary Casey ES 157 --Apple-Mail-44-181327765 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii I = think it is about radiation. The reason I did it was to reduce = the amount of heat radiated back at the cylinder heads. While a = shiny reflector might be more effective in theory, installing it = everywhere you would want it on a TSIO550 exhaust system is a lot = of work.

On Jan 12, 2012, = at 8:46 AM, Gary Casey wrote:

I guess I'm just not convinced about the = effectiveness of typical ceramic coatings. =46rom what I can find = out they are typically .001 to .002 thick, about 5% of the thickness of = the metal. In order to significantly reduce the heat transfer = compared to the metal, they would have to have thermal conductivity in = that order compared to steel. I can't find out what material is = used, but some might use zirconia, a very good insulator, which has = about 10 to 20% of the conductivity of steel. But that's not the = whole story. Inside the pipe is a gas at perhaps 1500F moving at a = relatively high velocity. The conductivity to the metal is = therefore relatively good, resulting in a metal temperature of probably = 1200F. The air on the outside is at about 180F and it is moving = slowly, so the heat transfer from the pipe to the air is "poor." My guess is that the = surface temperature of the ceramic is going to be very close to what the = metal would be without the coating. There just isn't enough = thickness for it to be well insulated. Swain Technologies has a = proprietary process that puts .015 thickness on metal and that would = probably work. A big factor in heat transfer is radiation and the = best way to reduce that is with a shiny metal surface spaced away from = the exhaust pipe, or from the device to be = protected.

Maybe ceramic coatings work well, = but I'm afraid I'm not convinced.

Gary = Casey

ES 157

= --Apple-Mail-44-181327765--