X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 16 Mar 2009 21:53:21 -0400 Message-ID: X-Original-Return-Path: Received: from [69.25.86.41] (HELO sodium.colo.stayonline.net) by logan.com (CommuniGate Pro SMTP 5.2.13) with ESMTP id 3549603 for lml@lancaironline.net; Mon, 16 Mar 2009 20:04:43 -0400 Received-SPF: neutral receiver=logan.com; client-ip=69.25.86.41; envelope-from=liegner@embarqmail.com X-ASG-Debug-ID: 1237181800-400a000d0000-yPXFKn X-Barracuda-URL: http://192.168.5.11:8000/cgi-bin/mark.cgi Received: from et-lax-20.site.stayonline.net (rrcs-24-43-148-194.west.biz.rr.com [24.43.148.194]) by sodium.colo.stayonline.net (Spam Firewall) with ESMTP id 3B0F23C3C60; Mon, 16 Mar 2009 01:36:40 -0400 (EDT) Received: from et-lax-20.site.stayonline.net (rrcs-24-43-148-194.west.biz.rr.com [24.43.148.194]) by sodium.colo.stayonline.net with ESMTP id la1JFSAaPuVOWKVK; Mon, 16 Mar 2009 01:36:40 -0400 (EDT) Received: from [10.1.10.95] ([172.16.0.74]) by et-lax-20.site.stayonline.net (8.12.6/8.12.6) with ESMTP id n2G5U8MM022996; Mon, 16 Mar 2009 05:30:09 GMT Mime-Version: 1.0 X-Sender: liegner@embarqmail.com@pop.embarqmail.com X-Original-Message-Id: In-Reply-To: References: X-Original-Date: Sun, 15 Mar 2009 18:32:40 -0400 X-Original-To: "Colyn Case at earthlink" From: "Jeffrey Liegner, MD" X-ASG-Orig-Subj: Re: [LML] Re: LOP vs ROP Climb: Time and Fuel Burn (LIVP) Subject: Re: [LML] Re: LOP vs ROP Climb: Time and Fuel Burn (LIVP) X-Original-Cc: "Lancair Mailing List" Content-Type: multipart/alternative; boundary="============_-974940696==_ma============" X-Barracuda-Connect: rrcs-24-43-148-194.west.biz.rr.com[24.43.148.194] X-Barracuda-Start-Time: 1237181801 X-Barracuda-Spam-Score: 1.85 X-Barracuda-Spam-Status: No, SCORE=1.85 using global scores of TAG_LEVEL=1000.0 QUARANTINE_LEVEL=1000.0 KILL_LEVEL=3.0 tests=DATE_IN_PAST_06_12, HTML_MESSAGE X-Barracuda-Spam-Report: Code version 3.2, rules version 3.2.1.20535 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------------------------- 1.85 DATE_IN_PAST_06_12 Date: is 6 to 12 hours before Received: date 0.00 HTML_MESSAGE BODY: HTML included in message --============_-974940696==_ma============ Content-Type: text/plain; charset="us-ascii" ; format="flowed" Your exhaust tunnels might be the component that favors this. In my standard exhaust configuration, the high pressure area where exhaust dumps under the belly would be higher in climb (nose up), and this high pressure area curtails exhaust outlet, requiring additional work to exhaust the gases, robbing some HP and thus amplifying retained heat. Your tunnels carry the exhaust back to the low pressure zone behind the wing root, and provides some facility to exiting gases that benefit heat exhaust. We would love to see a picture of these tunnels. I would also encourage some comments about LOP climbs at MAP 34" and above from the very wise George Braly. His advice will be helpful. Most of the professional Advance Engine talk is for either normally aspirated leaning or level cruise leaning via the BMP. Jeff L LIVP >Jeff, >that's interesting. I wonder why you get those high temps. >I wonder what is different in our engine setups. >my CHT's are steady @380 in the max/max condition @140knots. >It's been tested to 20,000 in that config. >CHT's get better than that with less power or more speed. >I have exhaust tunnel extensions which seem to make a huge >difference for cooling. >also have ceramic coated exhaust. I don't know how much of a factor that is. > >Some will say that 2700rpm is a bad idea because of higher friction losses. >On the other hand the flame front always moves at the same speed so if the >crank is turning faster your theta pp (angle after top dead center >where peak pressure occurs) is bigger >and the peak pressure is less. ....which seems good for everything. >the pulse on the crank >is not as concentrated, the CHT's are lower. assuming everything >else is setup right. > >Colyn --============_-974940696==_ma============ Content-Type: text/html; charset="us-ascii" Re: [LML] Re: LOP vs ROP Climb: Time and Fuel Burn (LIVP)
Your exhaust tunnels might be the component that favors this.  In my standard exhaust configuration, the high pressure area where exhaust dumps under the belly would be higher in climb (nose up), and this high pressure area curtails exhaust outlet, requiring additional work to exhaust the gases, robbing some HP and thus amplifying retained heat.  Your tunnels carry the exhaust back to the low pressure zone behind the wing root, and provides some facility to exiting gases that benefit heat exhaust.

We would love to see a picture of these tunnels.

I would also encourage some comments about LOP climbs at MAP 34" and above from the very wise George Braly.  His advice will be helpful.  Most of the professional Advance Engine talk is for either normally aspirated leaning or level cruise leaning via the BMP.

Jeff L
LIVP



Jeff,
that's interesting.  I wonder why you get those high temps.
I wonder what is different in our engine setups.
my CHT's are steady @380 in the max/max condition @140knots.
It's been tested to 20,000 in that config.
CHT's get better than that  with less power or more speed.
I have exhaust tunnel extensions which seem to make a huge difference for cooling.
also have ceramic coated exhaust.  I don't know how much of a factor that is.
 
Some will say that 2700rpm is a bad idea because of higher friction losses.
On the other hand the flame front always moves at the same speed so if the
crank is turning faster your theta pp (angle after top dead center where peak pressure occurs) is bigger
and the peak pressure is less.  ....which seems good for everything.  the pulse on the crank
is not as concentrated, the CHT's are lower.  assuming everything else is setup right.
 
Colyn

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