X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 08 Oct 2009 20:13:29 -0400 Message-ID: X-Original-Return-Path: Received: from n7a.bullet.mail.ac4.yahoo.com ([76.13.13.70] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with SMTP id 3878720 for lml@lancaironline.net; Thu, 08 Oct 2009 07:39:41 -0400 Received-SPF: none receiver=logan.com; client-ip=76.13.13.70; envelope-from=casey.gary@yahoo.com Received: from [76.13.13.25] by n7.bullet.mail.ac4.yahoo.com with NNFMP; 08 Oct 2009 11:39:06 -0000 Received: from [76.13.10.167] by t4.bullet.mail.ac4.yahoo.com with NNFMP; 08 Oct 2009 11:39:06 -0000 Received: from [127.0.0.1] by omp108.mail.ac4.yahoo.com with NNFMP; 08 Oct 2009 11:39:06 -0000 X-Yahoo-Newman-Property: ymail-3 X-Yahoo-Newman-Id: 272247.67761.bm@omp108.mail.ac4.yahoo.com Received: (qmail 89301 invoked by uid 60001); 8 Oct 2009 11:39:06 -0000 DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:X-YMail-OSG:Received:X-Mailer:References:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=jWkOrLFgyBZHB8iXe5N6H7drfL5B5VTrpowGGNENNw6idoBkTTnJp66NB9Ww+WmFgP/G5gQxL9Pnqb5hH9Kr/SXYvK0YpmxHrJ81QnqKy/qFIw9CWd+ZPC0A53B5QjdljttICDdYn1uT1AWp8cR7RtbqtR09ai2YbQGw1Yi/Vyk=; X-Original-Message-ID: <180656.88688.qm@web57501.mail.re1.yahoo.com> X-YMail-OSG: JfJILaQVM1lvJVr_8jaNk6TuQkxs_HNeWJP9rHygpuzO_YIjcgPSQQQalV.Cz6n4t4dJrAwKYae4HyHRbVzxFlHJr_zNCHpLld5BC1oE5rv1vG3tuCalfudsoYxReYOHpFyzhEZWjuNiudxDsn5ygo99jVEgeoe1eHobaCGF0k2N7k6DlxlGg5YDe_aNmQc4DBUtli8Y8EaxC.dYV8ANC_lhi9lvi2TisBxYoaosMvvGk_Or872amhC0EGeNtnds9DSkBBx3blGRTb_NbMA.KdSWMaXPCAG5kw5BevF29UpMou0iCOMjFRy9MQtygDBmCuNH3_awEvGp7hA- Received: from [97.122.189.50] by web57501.mail.re1.yahoo.com via HTTP; Thu, 08 Oct 2009 04:39:06 PDT X-Mailer: YahooMailRC/182.10 YahooMailWebService/0.7.347.3 References: X-Original-Date: Thu, 8 Oct 2009 04:39:06 -0700 (PDT) From: Gary Casey Subject: Re: LNC2 O-320D1F 1" Pull Back X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-422893224-1255001946=:88688" --0-422893224-1255001946=:88688 Content-Type: text/plain; charset=us-ascii Some things to try when the objective is to improve operation on a carburetor - a worthy endeavor for sure: True reducing the throttle opening by less than a 1" drop. Just a slight throttle angle change can affect the air/fuel distribution. Use the actual position (how far it is pulled back from the WOT stop) instead of a manifold pressure change, since the throttle can be closed quite a bit before there is a significant drop in MAP. If it works, you might be able to improve the situation without sacrificing power. One of the biggest improvements can be had by spacing the carburetor away from the engine, but that is probably not possible for most installations. Last, the inlet condition of the carb makes a very big difference in its operation. A nice bell inlet shape is probably not possible, but some kind of inlet radius might be workable. The air should enter uniformly from all sides. I've seen some installations where the asymmetry was really pronounced and there was seemingly no attempt made to create a uniform inlet condition. Sometimes the opposite of a bell intake works better - a uniform sharp edge can create a consistent turbulent flow, which might mix the charge better - but at a flow loss. Just some ideas. Gary Casey previous post: Lorn: I'm not an expert on the LOP for carb engines but it looks like you are operating at peak EGT at 6.3 gph. That's probably the worst place if I read the GAMI folks correctly. By closing the throttle 1 inch you might be moving the peaks around a bit but the idea they promote for carb engines is to operate WOT (wide open throttle) and then LOP, say 50d LOP, to get the best efficiency. From your iwork graph, I would suggest that if you can adjust the fuel flows on that hot cylinder then it appears to might be able to run down to the 5.9 gph area (or lower) and hopefully smooth operation or with limited vibration. The vibration at 6.3 gph doesn't surprise me because that is peak on three cylinders and lean on the #3 cylinder. I would send that into GAMI and see if they can add any useful information. But, I think the main issue to resolve is running at 6.3 because I think that is peak EGT according to your graph. If you can get down to 5.9 gph later without a lot of vibration I might look at extending that graph by a small amount by reducing FF slightly to get a good picture of where the speed and FF come out. good luck. Paul Miller Calgary ________________________________ --0-422893224-1255001946=:88688 Content-Type: text/html; charset=us-ascii
Some things to try when the objective is to improve operation on a carburetor - a worthy endeavor for sure:
True reducing the throttle opening by less than a 1" drop.  Just a slight throttle angle change can affect the air/fuel distribution.  Use the actual position (how far it is pulled back from the WOT stop) instead of a manifold pressure change, since the throttle can be closed quite a bit before there is a significant drop in MAP.  If it works, you might be able to improve the situation without sacrificing power.  One of the biggest improvements can be had by spacing the carburetor away from the engine, but that is probably not possible for most installations.  Last, the inlet condition of the carb makes a very big difference in its operation.  A nice bell inlet shape is probably not possible, but some kind of inlet radius might be workable.  The air should enter uniformly from all sides.  I've seen some installations where the asymmetry was really pronounced and there was seemingly no attempt made to create a uniform inlet condition.  Sometimes the opposite of a bell intake works better - a uniform sharp edge can create a consistent turbulent flow, which might mix the charge better - but at a flow loss.
Just some ideas.
Gary Casey

previous post: 
Lorn: I'm not an expert on the LOP for carb engines but it looks like you are operating at peak EGT at 6.3 gph.  That's probably the worst place if I read the GAMI folks correctly.    By closing the throttle 1 inch you might be moving the peaks around a bit but the idea they promote for carb engines is to operate WOT (wide open throttle) and then LOP, say 50d LOP, to get the best efficiency.  From your iwork graph, I would suggest that if you can adjust the fuel flows on that hot cylinder then it appears to might be able to run down to the 5.9 gph area (or lower) and hopefully smooth operation or with limited vibration.  The vibration at 6.3 gph doesn't surprise me because that is peak on three cylinders and lean on the #3 cylinder.  I would send that into GAMI and see if they can add any useful information.  But, I think the main issue to resolve is running at 6.3 because I think that is peak EGT according to your graph.    If you can get down to 5.9 gph later without a lot of vibration I might look at extending that graph by a small amount by reducing FF slightly to get a good picture of where the speed and FF come out.  good luck.

Paul Miller
Calgary



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