X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from ms-smtp-04.southeast.rr.com ([24.25.9.103] verified) by logan.com (CommuniGate Pro SMTP 5.1c.4) with ESMTP id 1415003 for flyrotary@lancaironline.net; Fri, 22 Sep 2006 09:16:49 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.103; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-100-038.carolina.res.rr.com [24.74.100.38]) by ms-smtp-04.southeast.rr.com (8.13.6/8.13.6) with SMTP id k8MDFXUI015647 for ; Fri, 22 Sep 2006 09:15:35 -0400 (EDT) Message-ID: <002e01c6de49$5a0a6f50$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Fuel Pressure Regulator Vacuum or Boost?? Date: Fri, 22 Sep 2006 09:16:44 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_002B_01C6DE27.D2AECE00" 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_002B_01C6DE27.D2AECE00 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Good questions, Thomas. Al indicated that the EC2 does indeed expect a manifold referenced = (vacuum for NA and vacuum/boost for forced induction) pressure = regulator. Therefore, the default fuel map for the EC2 is set up = expecting the pressure differential across the injector to remain = constant at all manifold pressures. Having the pressure differential = between the fuel rail and the manifold remain constant simplifies the = calculations for determining the PW to meet the engine demand. =20 You can certainly run the engine with a constant fuel pressure ( I have = - for close to 10 years) using the EC2. However, if the computer needs = to adjust every fuel map quantity for every pulse based on a constant = fuel pressure - which means the pressure differential is NOT constant = the problem becomes more complex. For instance, I suspect to do that = you would now need a fuel pressure sensor to feed the EC2, so the CPU = could determine what the fuel pressure differential is for each firing = and adjust the PW accordingly. So its much simpler to simply have the = fuel pressure regulator hold the pressure differential constant. This = way the EC2 only has to keep tabs on the manifold pressure instead of it = AND the fuel pressure. At least that is how it appears to me. Ed ----- Original Message -----=20 From: Thomas y Reina Jakits=20 To: Rotary motors in aircraft=20 Sent: Thursday, September 21, 2006 11:19 PM Subject: [FlyRotary] Re: Fuel Pressure Regulator Vacuum or Boost?? Ignorant Question: a) Does Tracy's system need/use manifold referenced fuel-pressure? b) If not shouldn't the fuel pressure stay constant (absolute), so = that the electronic control takes care of mixture with a fixed fuel = pressure and adjusts injector pulse according to manifold pressure? c) What advantage would you have in a system where the fuel is = manifold referenced directly? It still is controlled by the pulse = width.... Andvanced thanx for enlightening me! Thomas J. ----- Original Message -----=20 From: Ed Anderson=20 To: Rotary motors in aircraft=20 Sent: Thursday, September 21, 2006 3:26 PM Subject: [FlyRotary] Re: Fuel Pressure Regulator Vacuum or Boost?? Thanks, Bill, for confirming my suspicion. The 9 year old regulator = I am using was purchased because it had a manifold reference line and = was listed as a regulator for boost. I assumed (wrongly it appears) = that because it was referenced to the manifold that it would adjust fuel = pressure for manifold "vacuum" as well as positive boost. =20 After noting that some pressure regulators were for "Boost" and = others for "Vacuum/Boost" I came to suspect that the difference was not = just semantics in advertising. But, wanted someone who realllllyyyy = knew to put me straight. Ed ----- Original Message -----=20 From: wrjjrs@aol.com=20 To: Rotary motors in aircraft=20 Sent: Thursday, September 21, 2006 3:42 PM Subject: [FlyRotary] Re: Fuel Pressure Regulator Vacuum or Boost?? Ed, You are correct, the "boost reference" is only changed at more = than 1 atmosphere. The usually more expensive vacuum and boost = referenced unit would lower the pressure at idle. Bill Jepson=20 =20 -----Original Message----- From: joeh@pilgrimtech.com To: flyrotary@lancaironline.net Sent: Thu, 21 Sep 2006 11:48 AM Subject: [FlyRotary] Re: Fuel Pressure Regulator Vacuum or Boost?? I presume your pressure gauge remains steady as you adjust = throttle ? Yep, no real change in FP over the entire range from idle to WOT. Joe Hull Cozy Mk-IV N31CZ (65 hrs - Rotary 13B NA)=20 Redmond (Seattle), Washington -------------------------------------------------------------------------= - Check out the new AOL. Most comprehensive set of free safety and = security tools, free access to millions of high-quality videos from = across the web, free AOL Mail and more. ------=_NextPart_000_002B_01C6DE27.D2AECE00 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Good questions, Thomas.
 
Al indicated that the EC2 does indeed = expect a=20 manifold referenced (vacuum for NA and vacuum/boost for forced = induction)=20 pressure regulator.  Therefore, the default fuel map for the EC2 is = set up=20 expecting the pressure differential across the injector = to=20 remain constant at all manifold pressures.  Having the = pressure=20 differential between the fuel rail and the manifold remain=20 constant simplifies the calculations for determining the PW to meet = the=20 engine demand. 
 
You can certainly run the engine with a = constant=20 fuel pressure ( I have - for close to 10 years) using the=20 EC2.  However, if the computer needs to adjust every fuel = map=20 quantity for every pulse based on a constant fuel pressure - which = means=20 the pressure differential is NOT = constant the=20 problem becomes more complex.  For instance, I suspect to do that = you would=20 now need a fuel pressure sensor to feed the EC2, so the CPU could = determine what=20 the fuel pressure differential is for each firing and adjust the PW=20 accordingly.  So its much simpler to simply have the fuel pressure=20 regulator hold the pressure differential = constant.  This=20 way the EC2 only has to keep tabs on the manifold pressure instead of it = AND the=20 fuel pressure.
 
At least that is how it appears to = me.
 
Ed
----- Original Message -----
From:=20 Thomas y=20 Reina Jakits
Sent: Thursday, September 21, = 2006 11:19=20 PM
Subject: [FlyRotary] Re: Fuel = Pressure=20 Regulator Vacuum or Boost??

Ignorant Question:
 
a) Does Tracy's system need/use manifold = referenced=20 fuel-pressure?
b) If not shouldn't the fuel pressure stay = constant=20 (absolute), so that the electronic control takes care of mixture with = a fixed=20 fuel pressure and adjusts injector pulse according to manifold=20 pressure?
c) What advantage would you have in a system = where the=20 fuel is manifold referenced directly? It still is controlled by the = pulse=20 width....
 
Andvanced thanx for enlightening = me!
 
Thomas J.
----- Original Message -----
From:=20 Ed Anderson
To: Rotary motors in = aircraft=20
Sent: Thursday, September 21, = 2006 3:26=20 PM
Subject: [FlyRotary] Re: Fuel = Pressure=20 Regulator Vacuum or Boost??

Thanks, Bill, for confirming my=20 suspicion.  The 9 year old regulator I am using was purchased = because=20 it had a manifold reference line  and was listed as a regulator = for=20 boost.  I assumed (wrongly it appears) that because it was = referenced=20 to the manifold that it would adjust fuel pressure for manifold = "vacuum" as=20 well as positive boost. 
 
After noting that some pressure = regulators were=20 for "Boost" and others for "Vacuum/Boost" I came to suspect that the = difference was not just semantics in advertising.  But, wanted = someone=20 who realllllyyyy knew to put me straight.
 
Ed
----- Original Message ----- =
From:=20 wrjjrs@aol.com=20
To: Rotary motors in = aircraft=20
Sent: Thursday, September = 21, 2006=20 3:42 PM
Subject: [FlyRotary] Re: = Fuel=20 Pressure Regulator Vacuum or Boost??

Ed,
 You are correct, the "boost reference" is only changed = at more=20 than 1 atmosphere. The usually more expensive vacuum and boost = referenced=20 unit would lower the pressure at idle.
Bill Jepson 
 
 
-----Original Message-----
From: joeh@pilgrimtech.com
To: flyrotary@lancaironline.net
Sent:=20 Thu, 21 Sep 2006 11:48 AM
Subject: [FlyRotary] Re: Fuel = Pressure=20 Regulator Vacuum or Boost??

I presume your = pressure gauge=20 remains steady as you adjust throttle ?
 
Yep, no = real=20 change in FP over the entire range from idle to = WOT.
 
Joe = Hull
Cozy Mk-IV N31CZ (65 hrs - = Rotary 13B=20 NA)
Redmond (Seattle),=20 Washington
Check out the new AOL. Most = comprehensive set of=20 free safety and security tools, free access to millions of = high-quality=20 videos from across the web, free AOL Mail and=20 more.
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