X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from smtpauth06.mail.atl.earthlink.net ([209.86.89.66] verified) by logan.com (CommuniGate Pro SMTP 4.3c5) with ESMTP id 932803 for flyrotary@lancaironline.net; Wed, 04 May 2005 18:08:45 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.86.89.66; envelope-from=Dastaten@earthlink.net Received: from [24.238.206.157] (helo=earthlink.net) by smtpauth06.mail.atl.earthlink.net with asmtp (Exim 4.34) id 1DTS2D-00046Z-9U for flyrotary@lancaironline.net; Wed, 04 May 2005 18:08:01 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=simple; s=test1; d=earthlink.net; h=Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=DQZcJ3haXnB9XC+6BtP4P/wcCrr/dVbOAPqmZiqWIwG5MGJG8ZDFPVh3sUraRCE/; Message-ID: <427946E4.5020309@earthlink.net> Date: Wed, 04 May 2005 17:04:20 -0500 From: David Staten User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: EGT temps References: In-Reply-To: Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit X-ELNK-Trace: 9a30bff84e6cb88f95c85d38d22416599ef193a6bfc3dd48055f39caeb1539a1e040312a59c62fe4480e0e5d2f5ffe94350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 24.238.206.157

David Carter wrote:

A point I like to think of is that 50 or 80 degrees "from" "peak" on the rich side and on the lean side is, the same temperature. For piston engines, running 50 deg lean of peak is the same temp as running 50 deg rich of peak, so the valves are seeing the same temp - so why are some engine "gurus" so adament about cruising 50 deg rich of peak? It makes no sense to me.

So, I believe there is no such thing as "EGT too high". There is only "peak EGT", whatever it is for your installation.

David

If you look at the lycoming temp/power graphics that seem to make their way around this board, you will notice that while 50..(or 80) degrees rich OR lean of peak are the same temperature, their effect is NOT the same. The Cylinder Head Temps in the rich of peak equation have been documented to be hotter, and "best power" occurs on the rich of peak side, not AT peak EGT or lean of peak. Now, we HAVE water cooling to help attenuate the temps the block attains.. but the lesson to be learned is that running on the rich of peak side results in more heat generation which is more heat that must be dissipated.

The air cooled guys dont/shouldnt climb lean of peak primarily to avoid detonation and to use fuel for cooling. We probably could, but it helps to be aware of the events at play.

Dave