X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Tue, 25 Aug 2009 06:17:43 -0400 Message-ID: X-Original-Return-Path: Received: from web33905.mail.mud.yahoo.com ([209.191.69.183] verified) by logan.com (CommuniGate Pro SMTP 5.2.16) with SMTP id 3823542 for lml@lancaironline.net; Tue, 25 Aug 2009 00:22:22 -0400 Received-SPF: none receiver=logan.com; client-ip=209.191.69.183; envelope-from=wfhannahan@yahoo.com Received: (qmail 58066 invoked by uid 60001); 25 Aug 2009 04:21:47 -0000 DomainKey-Signature:a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com; h=Message-ID:X-YMail-OSG:Received:X-Mailer:Date:From:Subject:To:In-Reply-To:MIME-Version:Content-Type; b=yza5BhHYziox1IucWYPcM+qPRNZwCYvz43CcDEfuu5molYNZmRepsZNSzFIZZJAbUnWNqZSci+5GaYQ1jspUxj58lbOLHp63/F3WLVZ5mn01NRtaMwpxwMrXkD/ZT7RNYFKQuefZ4abEXwUYk4b+ZJiXrMsfPMmN2rHPSawT9TE=; X-Original-Message-ID: <924160.54360.qm@web33905.mail.mud.yahoo.com> X-YMail-OSG: in4i8GQVM1nsANQ74_BF_uFQFjyrTvBEA8XA8kEpT.jeMp0NLr9msU0UEFYSg_Q2dv1ljvS2Wa3z6NjHTlTVfNCgOPgZbdOyStVrv9iE1UZe.1PBWUkit1BoD9768T.4PTJwfAmZ5tS8TRNEhaEHjvQopmkztGKAl5B0pnShtBHxlYIMZvHfBmfnqracWE.xe0wPj3xFO4IDI1kGQoSzCrfO6o10K1PX0JU6i.JGGLn5aB8K.dDMqW9cvMw4cwAmy8l9I8dDt3adErmlKEtTHVB6Q38oOqjduQD0V22EndgOuCmAIZhgb1JBqeyUHVILU.loB8Bh0j.2Ve2_UXX_99uZ7lzxGg-- Received: from [71.213.175.38] by web33905.mail.mud.yahoo.com via HTTP; Mon, 24 Aug 2009 21:21:46 PDT X-Mailer: YahooMailClassic/6.1.2 YahooMailWebService/0.7.338.2 X-Original-Date: Mon, 24 Aug 2009 21:21:46 -0700 (PDT) From: Bill Hannahan Subject: Plenum pressure and Injector performance LOP X-Original-To: Lancair Mailing List In-Reply-To: MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="0-942092772-1251174106=:54360" --0-942092772-1251174106=:54360 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable =0A=0ATim, =0A=0A=A0=0A=0AIt sounds like very uneven fuel distribution. To = test your=0Atheory about cowl pressure you could try this experiment. =0A= =0A=A0=0A=0ASet up the power setting you want, then climb steeply to=0Amini= mum comfortable speed. Since dynamic pressure is proportional to velocity= =0Asquared this reduces the pressure differential across the engine to near= zero. Lean=0Ato slight trace of misfire. If it is lean of peak you are on = the right track. Accelerate=0Aback to normal speed and see if it gets rough= .=0A=0A=A0=0A=0AIs the incoming air blowing at high velocity on the front= =0Ainjectors, if so you might rig some temporary shields to protect them.= =0A=0A=A0=0A=0AAre there any fuel stains around the injectors indicating=0A= reverse flow.=0A=0A=A0=0A=0ALet us know what you find.=0A=0A=A0=0A=0A Regards, Bill Hannahan =20 wfhannahan@yahoo.com --- On Mon, 8/24/09, Tim Olson wrote: From: Tim Olson Subject: [LML] Plenum pressure and Injector performance LOP To: lml@lancaironline.net Date: Monday, August 24, 2009, 1:40 PM Hey guys, I am remembering a long time ago reading about how the air pressure surrounding the injector can affect how well the injector works.=A0 If I'm not mistaken, turbocharged engines even use some pressure manifold around the injector to accommodate for the increased Manifold Pressure. What gets me curious is that I'm having a discussion with some folks right now who are all having problems running Lean of Peak and their engines stumble before they get to peak EGT. Between the group, there are a variety of ignitions such as 2 mags or 1 lightspeed and one mag, and varieties such as 8.5:1, 9:1, and 10:1 compression ratios, but the one constant is that they all have what is purported to be a more effective cowl... the Sam James cowl with a plenum.=A0 So I'm wondering if the knowledge base some of you have would provide any insight to the issue. I originally was worried that the 10:1 pistons might make LOP operation harder to accomplish, but perhaps there is just too much air pressure on the outside of the injector?=A0 The cowl is known to often have too little exit area, so it could be that the pressure differential is even too high between the top and bottom half of the cowl. Any insight you can give? Thanks, Tim -- For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.html =0A=0A=0A --0-942092772-1251174106=:54360 Content-Type: text/html; charset=iso-8859-1 Content-Transfer-Encoding: quoted-printable
=0A=0A

Tim,

=0A=0A<= p class=3D"MsoNormal"> 

=0A=0A

It = sounds like very uneven fuel distribution. To test your=0Atheory about cowl= pressure you could try this experiment.

=0A=0A

<= o:p> 

=0A=0A

Set up the power setting y= ou want, then climb steeply to=0Aminimum comfortable speed. Since dynamic p= ressure is proportional to velocity=0Asquared this reduces the pressure dif= ferential across the engine to near zero. Lean=0Ato slight trace of misfire= . If it is lean of peak you are on the right track. Accelerate=0Aback to no= rmal speed and see if it gets rough.

=0A=0A

&= nbsp;

=0A=0A

Is the incoming air blowing at = high velocity on the front=0Ainjectors, if so you might rig some temporary = shields to protect them.

=0A=0A

 <= /p>=0A=0A

Are there any fuel stains around the inject= ors indicating=0Areverse flow.

=0A=0A

 <= /o:p>

=0A=0A

Let us know what you find.

=0A=0A<= p class=3D"MsoNormal"> 

=0A=0A

Regards,
Bill Hannahan

--- On Mon, 8/24/09, Tim Olson <Tim@5000feet.com> wrot= e:

From: Tim Olson <Tim@5000feet.com>=
Subject: [LML] Plenum pressure and Injector performance LOP
To: lml@= lancaironline.net
Date: Monday, August 24, 2009, 1:40 PM

Hey guys, I am remembering a long time ago reading abouthow the air pressure surrounding the injector can affect how
well the = injector works.  If I'm not mistaken, turbocharged
engines even use= some pressure manifold around the injector
to accommodate for the incre= ased Manifold Pressure.

What gets me curious is that I'm having a di= scussion with some
folks right now who are all having problems running Lean of Peak
and their engines stumble before t= hey get to peak EGT. Between
the group, there are a variety of ignitions= such as 2 mags
or 1 lightspeed and one mag, and varieties such as 8.5:1= ,
9:1, and 10:1 compression ratios, but the one constant is that
they= all have what is purported to be a more effective cowl...
the Sam James= cowl with a plenum.  So I'm wondering if the
knowledge base some o= f you have would provide any insight
to the issue. I originally was worr= ied that the 10:1 pistons
might make LOP operation harder to accomplish,= but perhaps
there is just too much air pressure on the outside of theinjector?  The cowl is known to often have too little exit
area, = so it could be that the pressure differential is
even too high between t= he top and bottom half of the
cowl.

Any insight you can give?
= Thanks,
Tim

--
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