X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sun, 15 Jan 2012 10:39:02 -0500 Message-ID: X-Original-Return-Path: Received: from mail.carneal.com ([174.129.224.69] verified) by logan.com (CommuniGate Pro SMTP 5.4.3) with ESMTPS id 5350173 for lml@lancaironline.net; Sat, 14 Jan 2012 10:34:46 -0500 Received-SPF: none receiver=logan.com; client-ip=174.129.224.69; envelope-from=walter@advancedpilot.com Received: (qmail 6233 invoked from network); 14 Jan 2012 15:34:09 -0000 Received: from c-75-71-5-203.hsd1.co.comcast.net (HELO ?10.0.1.5?) (walter@advancedpilot.com@75.71.5.203) by mail.carneal.com with ESMTPA; 14 Jan 2012 15:34:09 -0000 From: Walter Atkinson Mime-Version: 1.0 (Apple Message framework v1084) Content-Type: multipart/alternative; boundary=Apple-Mail-5-355697832 Subject: Re: [LML] Re: Ceramic exhaust coatings X-Original-Date: Sat, 14 Jan 2012 09:34:08 -0600 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: X-Mailer: Apple Mail (2.1084) --Apple-Mail-5-355697832 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Cheap, relatively light and effective... at making the exhaust metal = run hotter... if that's your objective. On Jan 13, 2012, at 5:26 AM, Randy wrote: One other thought, I have heard both sides of this argument before as = well. I also heard it is nearly impossible to weld / repair pipes with = this coating. I found a solution that solved the problem cheaply without = making the pipes more difficult to weld. I wrapped my entire exhaust = system with hot rod exhaust wrap. I bought it at the local auto parts = store in the 1" width. Spruce sells it as well. I tested the stuff with = a torch in the hangar on my hand and was amazed how well it insulates. I = have 2 layers in some very hot places on the pipes. In addition to = reducing the inner cowl temps, It also tames the vibration of the pipes = and reduces noise.=20 Cheap, relatively light and effective... Fwiw. Randy Snarr N694RS 235/320 Sent from my iPad On Jan 12, 2012, at 1:41 PM, Colyn Case wrote: > 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 >=20 >=20 > On Jan 12, 2012, at 8:46 AM, Gary Casey wrote: >=20 > 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. >=20 > Maybe ceramic coatings work well, but I'm afraid I'm not convinced. >=20 > Gary Casey > ES 157 >=20 --Apple-Mail-5-355697832 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii
One = other thought, I have heard both sides of this argument before as well. = I also heard it is nearly impossible to weld / repair pipes with this = coating. I found a solution that solved the problem cheaply without = making the pipes more difficult to weld. I wrapped my entire exhaust = system with hot rod exhaust wrap. I bought it at the local auto parts = store in the 1" width. Spruce sells it as well. I tested the stuff with = a torch in the hangar on my hand and was amazed how well it insulates. I = have 2 layers in some very hot places on the pipes. In addition to = reducing the inner cowl temps, It also tames the vibration of the pipes = and reduces noise. 
Cheap, relatively light and = effective...
Fwiw.

Randy = Snarr
N694RS
235/320

Sent from my = iPad

On Jan 12, 2012, at 1:41 PM, Colyn Case <colyncase@earthlink.net> = wrote:

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
=


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