Return-Path: Received: from [24.25.9.102] (HELO ms-smtp-03-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.2.8) with ESMTP id 612405 for flyrotary@lancaironline.net; Tue, 18 Jan 2005 19:32:21 -0500 Received-SPF: none receiver=logan.com; client-ip=24.25.9.102; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-185-127.carolina.rr.com [24.74.185.127]) by ms-smtp-03-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id j0J0Vnkd003842 for ; Tue, 18 Jan 2005 19:31:50 -0500 (EST) Message-ID: <012001c4fdbe$038e5690$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Air/Fuel Ratio Best Power [FlyRotary] Re: I got the power ! Date: Tue, 18 Jan 2005 19:30:01 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_011D_01C4FD94.1A88B310" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_011D_01C4FD94.1A88B310 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageMy research indicates that an air/fuel ratio (for gasoline) of = approx 12.65 is referred to as "Best Power". A lesser A/F ratio (13, = 14.7, 17, etc) will fail (theoretically) to burn all the oxygen = available in the mixture therefore leaving power on the table (had you = put in sufficient fuel to burn). However, I have also read that too = much fuel (A/F < 12.65) is counterproductive as you then tend to use = BTUs to vaporize fuel that can not burn due to lack of sufficient = oxygen. Some mixtures have more fuel than the theoretical optimum as = the fuel is used to "cool" and prevent detonation. =20 FWIW Ed Anderson ----- Original Message -----=20 From: Russell Duffy=20 To: Rotary motors in aircraft=20 Sent: Thursday, January 13, 2005 3:20 PM Subject: [FlyRotary] Re: I got the power ! If I recall correctly, the air/fuel mixture number was somewhere around 13... Make any sense?=20 Yep, sure does. The theoretical ideal air fuel ratio (AFR) is 14.7, = but that doesn't mean much to us. Any number lower than that is = richer, and of course higher numbers are leaner. Max power mixture is = richer than 14.7, and I'd suspect it might be close to your 13, but I'd = also bet that it depends on lots of other things as well. During lean = cruise, you will likely see numbers way up in the teens. =20 My old FD had a Power FC computer, and a wideband O2 sensor. I had it = tuned to around 11 AFR for full throttle, full boost, around 14-15 for = normal cruise, and I could even see the max of 20 on very light throttle = cruise. 11 AFR is pretty rich, and is needed to avoid detonation with = the turbos, but it shouldn't be needed for a NA engine. Bottom line is = that you'll have to do some testing to finish setting it up. =20 Rusty =20 ------=_NextPart_000_011D_01C4FD94.1A88B310 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
My research indicates that an air/fuel = ratio (for=20 gasoline) of approx 12.65 is referred to as "Best Power".  A lesser = A/F=20 ratio (13, 14.7, 17, etc) will fail (theoretically) to burn all the = oxygen=20 available in the mixture therefore leaving power on the table (had you = put in=20 sufficient fuel to burn).  However, I have also read that too much = fuel=20 (A/F < 12.65) is counterproductive as you then tend to use BTUs = to=20 vaporize fuel that can not burn due to lack of sufficient oxygen.  = Some=20 mixtures have more fuel than the theoretical optimum as the fuel is = used to=20 "cool" and prevent detonation. 
 
FWIW
 
Ed Anderson
----- Original Message -----
From:=20 Russell=20 Duffy
Sent: Thursday, January 13, = 2005 3:20=20 PM
Subject: [FlyRotary] Re: I got = the power=20 !

If I recall correctly, the
air/fuel mixture = number was=20 somewhere around 13... Make any sense? 

 
Yep, = sure does. =20 The theoretical ideal air fuel ratio (AFR) is 14.7, but that doesn't = mean much=20 to us.   Any number lower than that is richer, and of = course=20 higher numbers are leaner.   Max power mixture = is richer than=20 14.7, and I'd suspect it might be close to your 13, but I'd also bet = that it=20 depends on lots of other things as well.   During lean = cruise, you=20 will likely see numbers way up in the = teens.  
 
My old = FD had a Power=20 FC computer, and a wideband O2 sensor.  I had it tuned to around = 11 AFR=20 for full throttle, full boost, around 14-15 for normal cruise, and I = could=20 even see the max of 20 on very light throttle cruise.   11 = AFR is=20 pretty rich, and is needed to avoid detonation with the turbos, but it = shouldn't be needed for a NA engine.  Bottom line is that you'll = have to=20 do some testing to finish setting it = up.  
 
Rusty
   



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