Return-Path: Received: from imo-d06.mx.aol.com ([205.188.157.38] verified) by logan.com (CommuniGate Pro SMTP 4.2.8) with ESMTP id 618101 for flyrotary@lancaironline.net; Sun, 23 Jan 2005 03:02:49 -0500 Received-SPF: pass receiver=logan.com; client-ip=205.188.157.38; envelope-from=WRJJRS@aol.com Received: from WRJJRS@aol.com by imo-d06.mx.aol.com (mail_out_v37_r3.8.) id q.104.59358af1 (657) for ; Sun, 23 Jan 2005 03:02:17 -0500 (EST) From: WRJJRS@aol.com Message-ID: <104.59358af1.2f24b409@aol.com> Date: Sun, 23 Jan 2005 03:02:17 EST Subject: Re: [FlyRotary] Re: Fuel Injector Sizing To: flyrotary@lancaironline.net MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_104.59358af1.2f24b409_boundary" X-Mailer: 8.0 for Windows sub 6036 --part1_104.59358af1.2f24b409_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit In a message dated 1/22/2005 8:15:50 PM Pacific Standard Time, eanderson@carolina.rr.com writes: > Thanks Bulent, > > Yes, nice to have it confirmed. That was my understanding of how it should > work, but after two that did not work that way but did not cause any > operational difficulty - I went on to other problems {:>). > > So I would expect to see your fuel pressure around 37 psi with either the > engine stopped or WOT. Any RPM between those two extremes should result in > less than 37 psi on the gauge with the minimum psi during high speed idle > (lowest manifold pressure point). > > It would appear that I need to look for a new fuel pressure regulator. > > Ed, There is one more thing to think about in your system. Return restriction. If you have a powerful fuel pump, one that is a bit higher output than the one intended for the pressure regulator, there may be too much restriction in the return line to the tank to lower the pressure. The regulator opens the valve, but the pump overwhelms the ability of the return line to get the fuel back to the tank. In the old "dribble" style injectors like the old Hilborne mechanical systems the top end mixture was set by fuel pressure. A return jet to the tank was sized backward to normal for mixture. A larger jet lowered the return pressure and leaned the WOT mixture. Obviously the top was made richer with a smaller jet. You may have a situation where your return line is like a smaller jet. Since you are showing higher fuel pressure than Buly the logic still works. Since your pressure isn't extrodinarily high and you injectors are time rather than pressure based your system would still run fine. So long as the pressure wasn't so high as to prevent the injectors from closing the engine would run OK. Hope this might help. Bill Jepson --part1_104.59358af1.2f24b409_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable In a message dated 1/22/2005 8:15:5= 0 PM Pacific Standard Time, eanderson@carolina.rr.com writes:

Thanks Bulent,
 
Yes, nice to have it confirmed. That was my understanding of how it should=20= work, but after two that did not work that way but did not cause any operati= onal difficulty - I went on to other problems {:>).
 
So I would expect to see your fuel pressure around 37 psi with either the e= ngine stopped or WOT.  Any RPM between those two extremes should result= in less than 37 psi on the gauge with the minimum psi during high speed idl= e (lowest manifold pressure point). 

It would appear that  I need to look for a new fuel pressure regulator= .
 


Ed, There is one more thing to think about in your system. Return restrictio= n. If you have a powerful fuel pump, one that is a bit higher output than th= e one intended for the pressure regulator, there may be too much restriction= in the return line to the tank to lower the pressure. The regulator opens t= he valve, but the pump overwhelms the ability of the return line to get the=20= fuel back to the tank.
In the old "dribble" style injectors like the old Hilborne mechanical syste= ms the top end mixture was set by fuel pressure. A return jet to the tank wa= s sized backward to normal for mixture. A larger jet lowered the return pres= sure and leaned the WOT mixture. Obviously the top was made richer with a sm= aller jet.  You may have a situation where your return line is like a s= maller jet. Since you are showing higher fuel pressure than Buly the logic s= till works. Since your pressure isn't extrodinarily high and you injectors a= re time rather than pressure based your system would still run fine. So long= as the pressure wasn't so high as to prevent the injectors from closing the= engine would run OK. Hope this might help.
Bill Jepson --part1_104.59358af1.2f24b409_boundary--