Return-Path: Received: from fed1rmmtao06.cox.net ([68.230.241.33] verified) by logan.com (CommuniGate Pro SMTP 4.2.8) with ESMTP id 617411 for flyrotary@lancaironline.net; Sat, 22 Jan 2005 11:36:45 -0500 Received-SPF: none receiver=logan.com; client-ip=68.230.241.33; envelope-from=ALVentures@cox.net Received: from BigAl ([68.7.14.39]) by fed1rmmtao06.cox.net (InterMail vM.6.01.04.00 201-2131-117-20041022) with ESMTP id <20050122163614.VWSI17071.fed1rmmtao06.cox.net@BigAl> for ; Sat, 22 Jan 2005 11:36:14 -0500 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Manifold-Reference Fuel Pressure Date: Sat, 22 Jan 2005 08:36:19 -0800 Message-ID: <000001c500a0$805f6530$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C5005D.723C2530" 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 V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C5005D.723C2530 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Subject: [FlyRotary] Manifold-Reference Fuel Pressure was [FlyRotary] = Re: Fuel Injector Sizing =20 I agree with your statement, Buly. Ideally if the pressure differential between fuel rail and manifold is kept constant by use of a manifold reference then that would imply that the fuel pressure should vary to compensate for different manifold pressure. However, my fuel pressure = is rock steady and this is the second manifold-referenced fuel pressure regulator I have used with no difference. =20 Ed; =20 I'd say it is clear that your FPR is not functioning properly; although = the problem may not be in the pressure regulator. You may want to check to = make sure the manifold pressure (vacuum) is really being seen at the = regulator. =20 The fact that the fuel pressure does not change with MP is not a big = issue for NA engine. The idea of MP referencing of the fuel pressure came with super/turbo charging; the purpose is to keep the pressure differential across the injector nozzle from getting too low as the boost went up. = It is an issue with the EC2 because the default mixture mapping is set up for = MAP referenced fuel pressure. =20 =20 I did all the dyno runs with my engine without MAP reference; fixed at = 40 psi. This was before I knew that the EC2 was set up for MAP referenced = FP for NA application. It worked fine except it was difficult to get = things lean enough at idle. =20 With my current MAP referenced FPR and one fuel pump running, I have = about 41 psi fuel pressure with a MAP of 30", and about 31-32 psi at a MAP of 11-12". So that's about a 9 psi change in MAP resulting in about 9 psi change in fuel pressure. Keeps the pressure differential that the = injector sees constant. With both FPs running, the fuel pressure is a couple psi higher. =20 It was interesting yesterday; I ran the engine until the fuel tank was empty. I watched the FP as the pump started to suck air. I turned the mixture knob up as the FP started to drop. The engine continued to run = at low power until pressure got down to about 9 psi. =20 Al =20 ------=_NextPart_000_0001_01C5005D.723C2530 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Re: [FlyRotary] Re: Fuel Injector Sizing

Subject: [FlyRotary] Manifold-Reference Fuel Pressure was [FlyRotary] Re: Fuel Injector = Sizing

 

=

I agree with your = statement, Buly.  Ideally if the pressure differential between fuel rail and manifold is kept constant by use of a manifold reference then that = would imply that the fuel pressure should vary to compensate for different = manifold pressure.  However, my fuel pressure is rock steady and this is the = second manifold-referenced fuel pressure regulator I have used with no = difference.

 

Ed;

 

I’d say it is clear that your FPR is not functioning properly; although the = problem may not be in the pressure regulator.  You may want to check to = make sure the manifold pressure (vacuum) is really being seen at the = regulator.

 

The fact that the fuel pressure does not change with MP is not a big issue = for NA engine. The idea of MP referencing of the fuel pressure came with = super/turbo charging; the purpose is to keep the pressure differential across the = injector nozzle from getting too low as the boost went up.  It is an issue = with the EC2 because the default mixture mapping is set up for MAP referenced = fuel pressure. 

 

I did all the dyno runs with my engine without MAP reference; fixed at 40 = psi.  This was before I knew that the EC2 was set up for MAP referenced FP for = NA application.  It worked fine except it was difficult to get things = lean enough at idle.

 

With my current MAP referenced FPR and one fuel pump running, I have about 41 = psi fuel pressure with a MAP of 30”, and about 31-32 psi at a MAP of = 11-12”.  So that’s about a 9 psi change in MAP resulting in about 9 psi = change in fuel pressure.  Keeps the pressure differential that the injector = sees constant.  With both FPs running, the fuel pressure is a couple psi higher.

 

It was interesting yesterday; I ran the engine until the fuel tank was empty.  I watched the FP as the pump started to suck air.  I = turned the mixture knob up as the FP started to drop. The engine continued to = run at low power until pressure got down to about 9 psi.

 

Al

 

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