X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from ms-smtp-02.southeast.rr.com ([24.25.9.101] verified) by logan.com (CommuniGate Pro SMTP 5.1c.4) with ESMTP id 1413667 for flyrotary@lancaironline.net; Thu, 21 Sep 2006 13:57:36 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.101; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-110-158.carolina.res.rr.com [24.74.110.158]) by ms-smtp-02.southeast.rr.com (8.13.6/8.13.6) with SMTP id k8LHuRHF014739 for ; Thu, 21 Sep 2006 13:56:29 -0400 (EDT) Message-ID: <000601c6dda7$6c447320$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" Subject: Fuel Pressure Regulator Vacuum or Boost?? Date: Thu, 21 Sep 2006 13:57:35 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0003_01C6DD85.E4445470" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2869 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2962 X-Virus-Scanned: Symantec AntiVirus Scan Engine This is a multi-part message in MIME format. ------=_NextPart_000_0003_01C6DD85.E4445470 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable For the entire life of my rotary powered RV-6A, I have flown with a = "Boost Referenced" adjustable fuel pressure regulator from MSD. As you = know, it is desirable to keep the pressure differential between the = injector fuel rail pressure and the manifold pressure a constant for = best fuel injection control. =20 I flew for several years thinking that since my pressure regulator was = manifold reference that it was indeed doing this. Then the light bulb = came on - my fuel pressure holds rock-steady at 43 PSI - and does not = vary between idle and WOT! This certainly implies that the fuel = pressure IS NOT varying as a function of manifold pressure. Then doing some recent research on fuel pressure regulators, I noticed = that some say they are "Boost Referenced" and other's say "Vacuum/Boost = Referenced". My conclusion (which may be incorrect) is that while my = pressure regulator is "Boost Referenced" it is not "Vacuum Referenced". = The difference (If I understand it correctly ) is that my regulator = would increase fuel pressure IF it ever encounter manifold pressure = greater than ambient - since I am not used forced induction that never = happens - which in turn appears to be the reason I never see the fuel = pressure changing in response to manifold "vacuum". So my question to those who realllllllyyyyyy know - is it correct that = for my NA 13B I need a fuel pressure regulator that responses to = manifold "Vacuum" or is the difference in description between "vacuum = referenced and boost referenced " just semantics in advertising? Thanks Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://members.cox.net/rogersda/rotary/configs.htm#N494BW ------=_NextPart_000_0003_01C6DD85.E4445470 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

For the entire life of my rotary powered RV-6A, = I have=20 flown with a "Boost Referenced" adjustable fuel pressure regulator from=20 MSD. As you know, it is desirable to keep the pressure = differential=20 between the injector fuel rail pressure and the manifold pressure a = constant for=20 best fuel injection control.

I flew for several years thinking that since my = pressure=20 regulator was manifold reference that it was indeed doing this. = Then the=20 light bulb came on - my fuel pressure holds rock-steady at 43 PSI - and = does not=20 vary between idle and WOT! This certainly implies that the fuel = pressure=20 IS NOT varying as a function of manifold pressure.

Then doing some recent research on fuel pressure = regulators, I noticed that some say they are "Boost Referenced" and = other's say=20 "Vacuum/Boost Referenced". My conclusion (which may be = incorrect)=20 is that while my pressure regulator is "Boost Referenced" it is = not=20 "Vacuum Referenced". The difference (If I understand it correctly = ) is=20 that my regulator would increase fuel pressure IF it ever encounter = manifold=20 pressure greater than ambient - since I am not used forced induction = that never=20 happens - which in turn appears to be the reason I never see the fuel = pressure=20 changing in response to manifold "vacuum".

So my question to those who realllllllyyyyyy = know -=20 is it correct that for my NA 13B I need a fuel pressure regulator = that=20 responses to manifold "Vacuum" or is the difference in description = between=20 "vacuum referenced and boost referenced " just semantics in=20 advertising?

Thanks

Ed Anderson
Rv-6A N494BW Rotary = Powered
Matthews,=20 NC
eanderson@carolina.rr.comhttp:/= /members.cox.net/rogersda/rotary/configs.htm#N494BW

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