X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from fed1rmmtao08.cox.net ([68.230.241.31] verified) by logan.com (CommuniGate Pro SMTP 5.1c.4) with ESMTP id 1414352 for flyrotary@lancaironline.net; Thu, 21 Sep 2006 23:15:10 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.31; envelope-from=alventures@cox.net Received: from fed1rmimpo02.cox.net ([70.169.32.72]) by fed1rmmtao08.cox.net (InterMail vM.6.01.06.01 201-2131-130-101-20060113) with ESMTP id <20060922031429.KUDO22977.fed1rmmtao08.cox.net@fed1rmimpo02.cox.net> for ; Thu, 21 Sep 2006 23:14:29 -0400 Received: from BigAl ([72.192.132.90]) by fed1rmimpo02.cox.net with bizsmtp id RFEW1V00e1xAn3c0000000 Thu, 21 Sep 2006 23:14:30 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Fuel Pressure Regulator Vacuum or Boost?? Date: Thu, 21 Sep 2006 20:14:37 -0700 Message-ID: <000001c6ddf5$3c727d60$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C6DDBA.9013A560" 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 V6.00.2900.2962 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C6DDBA.9013A560 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Ed; =20 I started with a fixed pressure regulator at 42-43#, which would = normally be fine for NA. When I was having trouble getting the engine to idle right with Tracy's EC2; he mentioned that his programming was set up assuming = a manifold pressure referenced regulator. TWM was kind enough to trade me straight across for one that was pressure referenced - pressure at idle = now is low 30's, and it helped getting good idle. =20 I guess "boost referenced" means just that; for MAP above normal atmospheric. =20 Al =20 -----Original Message----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson Sent: Thursday, September 21, 2006 9:58 AM To: Rotary motors in aircraft Subject: [FlyRotary] Fuel Pressure Regulator Vacuum or Boost?? =20 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 =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. =20 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". =20 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? =20 Thanks =20 Ed =20 Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://members.cox.net/rogersda/rotary/configs.htm#N494BW ------=_NextPart_000_0001_01C6DDBA.9013A560 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Ed;

 

I started with a fixed pressure regulator at 42-43#, which would normally be fine for NA.  When I = was having trouble getting the engine to idle right with Tracy’s EC2; = he mentioned that his programming was set up assuming a manifold pressure referenced regulator.  TWM was kind enough to trade me straight = across for one that was pressure referenced – pressure at idle now is low = 30’s, and it helped getting good idle.

 

I guess “boost = referenced” means just that; for MAP above normal atmospheric.

 

Al

 

-----Original = Message-----
From: Rotary motors in = aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Ed Anderson
Sent: Thursday, September = 21, 2006 9:58 AM
To: Rotary motors in = aircraft
Subject: [FlyRotary] Fuel = Pressure Regulator Vacuum or Boost??

 

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.  =

 

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

=
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