X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from ms-smtp-01.southeast.rr.com ([24.25.9.100] verified) by logan.com (CommuniGate Pro SMTP 5.1c.4) with ESMTP id 1413744 for flyrotary@lancaironline.net; Thu, 21 Sep 2006 14:39:53 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.100; 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-01.southeast.rr.com (8.13.6/8.13.6) with SMTP id k8LIcimN009715 for ; Thu, 21 Sep 2006 14:38:46 -0400 (EDT) Message-ID: <000701c6ddad$54450d10$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Fuel Pressure Regulator Vacuum or Boost?? Date: Thu, 21 Sep 2006 14:39:51 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0004_01C6DD8B.CBAEC8E0" 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_0004_01C6DD8B.CBAEC8E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Clearly not crucial ):<), Barry. Based on my experience with Tracy's Default EC2 settings - it appears = that my engine always runs bit rich at idle. Yes, I can/have adjusted = the MAP values to compensate for this but still have a rather irregular = idle at times - acts as if too rich. With the fuel pressure adjusted to = compensate for manifold pressure, then each millisecond of injector time = injectors the same amount of fuel. So I am not certain as to whether = this has any bearing on my idle but when you seem to have eliminated all = else - this remains and makes me wonder. In my research, I have found this type of description of what a pressure = regulator (manifold referenced) is suppose to do so causes me to wonder = whether I have the correct type. I know I do not have a 0.49 psi drop = for each inch Hg drop in manifold pressure. If I have 43 psi at WOT = then according to the description below I should have approx 0.49 * 15 = =3D 7 psi drop in fuel pressure at 15 inch Hg in manifold pressure or - = it should drop from 43 to 35 psi (approx) which it does not. Ed To take a fuel pressure reading, you have to remember that during idle, = the vacuum causes the fuel pressure regulator to lower the fuel pressure = to maintain 55psi between the fuel pressure and the manifold pressure. = For every 1inHg of vacuum, there is a 0.49psi drop in pressure at the = rail. So, 15inHg of vacuum will make about 47.6psi of fuel pressure on = a stock regulator. To accurately set the fuel pressure, you either have = to calculate the proper fuel pressure by measuring the manifold vacuum, = or you need to unplug the vacuum line from the regulator. This will = make the regulator think the manifold is at 0psi of pressure and the = fuel pressure will rise to 55psi. Do not leave the regulator unplugged = when you are done! If you drive your car with the regulator unplugged, = the engine will lean-out and severe engine damage could result! While = at idle, the engine will run rich because of the rise in fuel pressure, = so don't do it for too long. With your fuel pressure now at a constant, = atmospheric pressure, you can reliably adjust it. To lower the fuel = pressure, turn the adjusting screw on the adjustable regulator = counter-clockwise. To raise it, turn it clockwise. With the engine = idling, you will see the pressure change on your guage. ----- Original Message -----=20 From: Barry Gardner=20 To: Rotary motors in aircraft=20 Sent: Thursday, September 21, 2006 2:06 PM Subject: [FlyRotary] Re: Fuel Pressure Regulator Vacuum or Boost?? Ed, If stock automotive regulators don't take vacuum into account (to the = best of my knowledge, anyhow), is it important? Barry Gardner Wheaton, IL ----- Original Message -----=20 From: Ed Anderson=20 To: Rotary motors in aircraft=20 Sent: Thursday, September 21, 2006 12:57 PM 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. =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_0004_01C6DD8B.CBAEC8E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Clearly not crucial ):<), Barry.
 
  Based on my experience with Tracy's = Default EC2=20 settings - it appears that my engine always runs  bit rich at = idle. =20 Yes, I can/have adjusted the MAP values to compensate for this but still = have a=20 rather irregular idle at times - acts as if too rich.  With the = fuel=20 pressure adjusted to compensate for manifold pressure, then each = millisecond of=20 injector time injectors the same amount of fuel.   So I am not = certain=20 as to whether this has any bearing on my idle but when you seem to have=20 eliminated all else - this remains and makes me wonder.
 
In my research, I have found this type of = description of=20 what a pressure regulator (manifold referenced)  is suppose to do = so causes=20 me to wonder whether I have the correct type.  I know I do not have = a 0.49=20 psi drop for each inch Hg drop in manifold pressure.  If I have 43 = psi at=20 WOT then according to the description below I should have approx 0.49 * = 15 =3D 7=20 psi drop in fuel pressure at 15 inch Hg in manifold pressure or - it = should drop=20 from 43 to 35 psi (approx) which it does not.
 
Ed
 
To take a fuel pressure reading, you have to remember that during = idle, the=20 vacuum causes the fuel pressure regulator to lower the fuel pressure to = maintain=20 55psi between the fuel pressure and the manifold pressure.  For = every 1inHg=20 of vacuum, there is a 0.49psi drop in pressure at the rail.  So, = 15inHg of=20 vacuum will make about 47.6psi of fuel pressure on a stock = regulator.  To=20 accurately set the fuel pressure, you either have to calculate the = proper fuel=20 pressure by measuring the manifold vacuum, or you need to unplug the = vacuum line=20 from the regulator.  This will make the regulator think the = manifold is at=20 0psi of pressure and the fuel pressure will rise to 55psi.  Do = not leave=20 the regulator unplugged when you are done!  If you drive your car = with the=20 regulator unplugged, the engine will lean-out and severe engine damage = could=20 result!  While at idle, the engine will run rich because of the = rise in=20 fuel pressure, so don't do it for too long.  With your fuel = pressure now at=20 a constant, atmospheric pressure, you can reliably adjust it.  To = lower the=20 fuel pressure, turn the adjusting screw on the adjustable regulator=20 counter-clockwise.  To raise it, turn it clockwise.  With the = engine=20 idling, you will see the pressure change on your guage.
----- Original Message -----
From:=20 Barry=20 Gardner
Sent: Thursday, September 21, = 2006 2:06=20 PM
Subject: [FlyRotary] Re: Fuel = Pressure=20 Regulator Vacuum or Boost??

Ed,
 
If stock automotive regulators don't = take vacuum=20 into account (to the best of my knowledge, anyhow), is it=20 important?
 
Barry Gardner
Wheaton, IL
----- Original Message -----
From:=20 Ed Anderson
To: Rotary motors in = aircraft=20
Sent: Thursday, September 21, = 2006=20 12:57 PM
Subject: [FlyRotary] Fuel = Pressure=20 Regulator Vacuum or Boost??

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=20 for best fuel injection control. 
 
I flew for several years thinking that since = my=20 pressure regulator was manifold reference that it was indeed doing=20 this.  Then the light bulb came on - my fuel pressure holds = rock-steady=20 at 43 PSI - and does not vary between idle and WOT!  This = certainly=20 implies that the fuel pressure IS NOT varying as a function of = manifold=20 pressure.
 
Then doing some recent research on fuel = pressure=20 regulators, I noticed that some say they are "Boost Referenced" and = other's=20 say "Vacuum/Boost Referenced".   My conclusion (which may = be=20 incorrect)  is that while my pressure regulator is "Boost = Referenced"=20 it is not "Vacuum Referenced".  The difference (If I understand = it=20 correctly ) is that my regulator would increase fuel pressure IF it = ever=20 encounter manifold pressure greater than ambient - since I am not = used=20 forced induction that never happens - which in turn appears to be = the reason=20 I never see the fuel pressure changing in response to manifold=20 "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
 
Ed Anderson
Rv-6A N494BW Rotary=20 Powered
Matthews, NC
eanderson@carolina.rr.comhttp:/= /members.cox.net/rogersda/rotary/configs.htm#N494BW
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