X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from wproxy.gmail.com ([64.233.184.238] verified) by logan.com (CommuniGate Pro SMTP 5.0.9) with ESMTP id 1056428 for flyrotary@lancaironline.net; Sun, 02 Apr 2006 21:29:02 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.233.184.238; envelope-from=russell.duffy@gmail.com Received: by wproxy.gmail.com with SMTP id i30so1056601wra for ; Sun, 02 Apr 2006 18:28:17 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:from:to:subject:date:message-id:mime-version:content-type:x-priority:x-msmail-priority:x-mailer:importance:in-reply-to:x-mimeole; b=KIjQJCooZFQqGUA6FZZDAUnLDffCH5md3vvciAq7jKDxo/vy2sLrqjIelMzhZ4oB+T+a614LveXUhx31vRa1e+hLPfs0HSGT6ChNO14dIBULcAObzxPBW5he5R6tJczAIJht55pqOG9o21oQYKKDiSceFEggPTPStpXh2NMRZNg= Received: by 10.54.144.20 with SMTP id r20mr2577598wrd; Sun, 02 Apr 2006 18:28:17 -0700 (PDT) Return-Path: Received: from rd ( [65.6.194.9]) by mx.gmail.com with ESMTP id 28sm118240wrl.2006.04.02.18.28.16; Sun, 02 Apr 2006 18:28:17 -0700 (PDT) From: "Russell Duffy" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Erratic mixture Date: Sun, 2 Apr 2006 20:28:17 -0500 Message-ID: <000001c656bd$e2bb4810$6101a8c0@rd> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C65693.F9E54010" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2670 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C65693.F9E54010 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable I have seen the FP changing=20 from 35 psi at low RPM to 50 psi at high boost? =20 Hi Buly, =20 What you describe here is exactly how it's supposed to work, and whether = you believe it or not, it's making your tuning life easier. Here's why... =20 Think about how a fuel injector works. The fuel rail has a high = pressure in it, and the intake end of the injector is in a lower pressure area. To actuate the injector, all you're doing is opening it. The rate of fuel = flow is controlled by the difference between the pressure in the fuel rail, = and the pressure in your intake. =20 =20 As you can see, if you were to set your fuel pressure at a fixed point, = then run lots of boost, there would be very little flow across the injector, because the differential pressure would be low. This will make your injector appear to get smaller as boost increases, and eventually you = will go lean. Recall also that lean + boost =3D rebuild :-( =20 The whole idea of the rising rate fuel pressure regulator is to keep the differential pressure close to the same, so the injector flows the same = rate of fuel regardless of the MAP. This makes it easier for the engine = computer to control idle to max boost mixtures. =20 Cheers, Rusty (Stopped to eat in Greenville AL in George's honor today ) =20 =20 ------=_NextPart_000_0001_01C65693.F9E54010 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Message

I have seen the FP changing 
from 35 psi at = low RPM to=20 50 psi at high boost?

 
Hi=20 Buly,
 
What you = describe here=20 is exactly how it's supposed to work, and whether you believe it or not, = it's=20 making your tuning life easier.  Here's why...
 
Think = about how a fuel=20 injector works.  The fuel rail has a high pressure in it, and the = intake=20 end of the injector is in a lower pressure area.  To actuate the = injector,=20 all you're doing is opening it.  The rate of fuel flow is = controlled by the=20 difference between the pressure in the fuel rail, and the pressure in = your=20 intake.  
 
As you = can see, if you=20 were to set your fuel pressure at a fixed point, then run lots of boost, = there=20 would be very little flow across the injector, because the differential = pressure=20 would be low.  This will make your injector appear to get smaller = as boost=20 increases, and eventually you will go lean.  Recall also that lean = + boost=20 =3D rebuild :-(
 
The = whole idea of the=20 rising rate fuel pressure regulator is to keep the differential pressure = close=20 to the same, so the injector flows the same rate of fuel regardless of = the=20 MAP.  This makes it easier for the engine computer to control = idle to=20 max boost mixtures.
 
Cheers,
Rusty (Stopped to eat = in Greenville AL=20 in George's honor today <g>)
 
 



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