X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2327964 for flyrotary@lancaironline.net; Wed, 12 Sep 2007 22:57:57 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.120; envelope-from=echristley@nc.rr.com Received: from [192.168.0.75] (really [66.57.38.121]) by cdptpa-omta02.mail.rr.com with ESMTP id <20070913025721.WQOL3965.cdptpa-omta02.mail.rr.com@[192.168.0.75]> for ; Thu, 13 Sep 2007 02:57:21 +0000 Message-ID: <46E8A710.8080805@nc.rr.com> Date: Wed, 12 Sep 2007 22:57:20 -0400 From: Ernest Christley User-Agent: Thunderbird 1.5.0.13 (X11/20070824) MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: How cool is too cool? References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit John Slade wrote: > >>I'd heard oil needs to see 212f minimum at some point so that it can > boil off moisture that develops. > >Actually, at 6000 feet, where a lot of folks fly, the boiling point > drops > >to 201F. At 10K feet, it is only 192. Perhaps thats true at ambient > pressure, but surely - not at 80 PSI. :) > John > Dude, if the oil in your sump is at 80psi, something is either broken or soon will be. 8*) My understanding is that oil is constantly pickup up water from combustion byproducts. The desired running temperature is set such that the water is boiled off at least as fast as it's coming in. An engine with good compression will have less blow-by and can get by with lower temps. The smoky contraption that Detroit was turning out in the 70's, with gaps in the seal that you could read through, needs an extra flame to heat the oil just to keep up. (Yes, I exaggerate). I would think that we could run a little cooler in airplanes without issue, because we don't have to burn off the extra water that has built up from short drives where the oil barely got warm.