X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Sat, 06 Oct 2007 12:19:33 -0400 Message-ID: X-Original-Return-Path: Received: from wind.imbris.com ([216.18.130.7] verified) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTPS id 2372510 for lml@lancaironline.net; Sat, 06 Oct 2007 12:06:57 -0400 Received-SPF: none receiver=logan.com; client-ip=216.18.130.7; envelope-from=brent@regandesigns.com Received: from [192.168.1.100] (wireless-135-19.imbris.com [216.18.135.19]) (authenticated bits=0) by wind.imbris.com (8.12.11/8.12.11.S) with ESMTP id l96G6DdA062369 for ; Sat, 6 Oct 2007 09:06:13 -0700 (PDT) (envelope-from brent@regandesigns.com) X-Original-Message-ID: <4707B2EB.5060700@regandesigns.com> X-Original-Date: Sat, 06 Oct 2007 09:08:11 -0700 From: Brent Regan User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.2) Gecko/20040804 Netscape/7.2 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 X-Original-To: Lancair Mailing List Subject: Re: [LML] video of cyl firing Content-Type: multipart/alternative; boundary="------------010506070400020309030705" This is a multi-part message in MIME format. --------------010506070400020309030705 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit OK Walter, I'll bite. It appears that the fuel "fog" transparency is lowest too early in the cycle. The fog indicates the presence of liquid droplets, similar to what happens over the wing of a fighter in a high alpha turn on a humid day. I would think the fuel of a homogeneous mixture would form at the point of highest pressure drop (temperature drop), which should happen closer to maximum piston velocity (mid stroke). Also, there appears to be fuel droplets striking the back of the valve late in the intake cycle. You could be more certain if the "deg CA" (degrees crank angle) indicator wasn't pixelated. I assume that when you say "injection" you are referring to typical aircraft injection, which has a continuos fuel flow rather than timed injection. With continuos injection a load of fuel builds in the induction system during 3 of the 4 cycles. When the intake opens, a super rich mixture is followed by a very lean mixture and lots of slobbering. With carbureted and timed injection the charge is more homogeneous. My vote is for continuos or PWM injection. It is interesting that the first few frames show the piston at near TDC but there is no overlap. Also, there is fuel fog the moment the intake opens, indicating that exhaust scavenging or induction tuning or supercharging is taking place and the cylinder pressure is below the manifold pressure. It is possible that apparent fuel mixture bias is is due to the transition of this effect to piston induced pressure drop but the fuel slobbering at the end of the stroke still points to C.I.. Do you know the circumstances of this engine? Cool video, BTW. Thanks Rob! Regards Brent Regan --------------010506070400020309030705 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit OK Walter, I'll bite.

It appears that the fuel "fog" transparency is lowest too early in the cycle. The fog indicates the presence of liquid droplets, similar to what happens over the wing of a fighter in a high alpha turn on a humid day. I would think the fuel of a homogeneous mixture would form at the point of highest pressure drop (temperature drop), which should happen closer to maximum piston velocity (mid stroke). Also, there appears to be fuel droplets striking the back of the valve late in the intake cycle.  You could be more certain if the "deg CA" (degrees crank angle) indicator wasn't pixelated.

I assume that when you say "injection" you are referring to typical aircraft injection, which has a continuos fuel flow rather than timed injection. With continuos injection a load of fuel builds in the induction system during 3 of the 4 cycles. When the intake opens, a super rich mixture is followed by a very lean mixture and lots of slobbering.

With carbureted and timed injection the charge is more homogeneous.

My vote is for continuos or PWM injection.

It is interesting that  the first few frames show the piston at near TDC  but there is no overlap. Also, there is fuel fog the moment the intake opens, indicating that exhaust scavenging or induction tuning or supercharging is taking place and the cylinder pressure is below the manifold pressure. It is possible that  apparent fuel mixture bias is is due to the transition of this effect to piston induced pressure drop but the fuel slobbering at the end of the stroke still points to C.I..

Do you know the circumstances of this engine?

Cool video, BTW. Thanks Rob!

Regards
Brent  Regan
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