Return-Path: Received: from [65.33.84.140] (account ) by logan.com (CommuniGate Pro WebUser 4.1b3) with HTTP id 2132183 for ; Thu, 17 Apr 2003 09:09:33 -0400 From: "Marvin Kaye" Subject: Re: [FlyRotary] Re: fuel return To: flyrotary X-Mailer: CommuniGate Pro WebUser Interface v.4.1b3 Date: Thu, 17 Apr 2003 09:09:33 -0400 Message-ID: In-Reply-To: <005201c304e2$34c2af80$1702a8c0@WorkGroup> MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format="flowed" Content-Transfer-Encoding: 8bit Posted for "Ed Anderson" : Welcome to the club,David {:>) lots of things I don't understand also- but, here is my crack at your question. My pumps puts out approx 80 psi at idle (without pressure regulator) when new and the flow rate was given in the specs as 43 gph at 45 psi. Clearnly adequate even for a turbo 13B. The main pump, after 5 years of use, is down to about 65 psi (without pressure regulator) - so apparently it is getting a bit worn from use and due to be replaced. This pressure is without the pressure regulator. With the pressure regulator, I have it set so I get approx 43 psi. Of course, the way I get 43 psi is to set the regulator to by-pass sufficient fuel back to my header tank to drop the line pressure from 65-80 psi to 43 psi. It does not take much fuel being by-passed by the regulator back to my sump to drop the pressure quite a bit. Imagine trying to maintain 80 psi from the pump with a 1/4-3/8" dia hole in the line. I estimated at one point that my regulator by-passed a max of approx 8-9 gallon hour and that was at idle. Less fuel is returned when the injectors are full blast. I have seen over 20 gph fuel flow on a cold morning. I am not certain that the pump is working harder with more flow. It may be that the pressure regulator is simply not diverting as much of the pump's flow back to the tank. . If pressure were required to be maintained at say 60 psi at 16 gph for example then it would have to work harder than if it maintained 16 gph at 43 psi. But, more importantly that is why the pump rating should accommodate the intended application. These pumps would clearly not support a 1000 HP dragester fuel flow needs for example. Perhaps this helps a bit. Ed