[Diy_efi] Donegan ECU

[cobraman at insightbb.com]

Greg, 

How much fuel @ 45psi will flow through the .045?  Do I need more pump?  What is the expected pressure drop?  Thanks  TomS

----- Original Message -----
From: "bearbvd at mindspring.com" <bearbvd at mindspring.com>
Date: Saturday, January 6, 2007 23:50
Subject: Re: [Diy_efi] Donegan ECU
To: diy_efi at diy-efi.org

> 
> 
> Original Message:
> -----------------
> From: Steven P. Donegan donegan at donegan.org
> Date: Fri, 05 Jan 2007 10:40:53 -0800
> To: diy_efi at diy-efi.org
> Subject: Re: [Diy_efi] Donegan ECU
> 
> 
>  > On Thu, 2007-01-04 at 12:23 -0600, 
> cobraman at insightbb.com wrote:
> > > > My "Edelbrick" ProFlow has fuel pressure controlled with 
> > > engine vacuum. On track sessions on very hot days, the fuel 
> in 
> > > the rails will boil under hard braking - accelerator closed 
> (low 
> > > fuel pressure). When you finally step on it (52 psi), 
> nothing 
> > > happens until the vapor "recirculates" or is expelled.  
> > > Usually takes a second or so.  I don't think dead 
> heading 
> > > would do any better - probably just need to keep a constant 
> fuel 
> > > pressure. 
> > > > IMHO, hot fuel should give better economy - easier to 
> vaporize 
> > > - for those green members.  TomS
> > > > 
> > > > 
> > > > 
> > > > 
> > > > 
> > > > 
> > > > 
> > > > ld
> > > > > consume the gas in the rails well before it got warm :-) 
> > > However this
> > > > > does raise a point - perhaps my ECM/PCM/EFI computer 
> needs a 
> > > way 
> > > > > to open
> > > > > a fuel return line and to sense fuel temp in the rails? 
> Any 
> > > > > ideas on how
> > > > > useful that would be in the 'real world' anyone?
> > > > > 
> First-- plumb the rails as with any 'two phase' (gas/liquid) 
> piping system.
> Industrial refrigeration piping practice is a good example. Injectors
> pointed downward--where you want liquid. Uniform slope to one 
> high point,
> so that no vapor is 'trapped' anywhere but at the high point. 
> Finally--put
> a fixed size bypass/return orifice--about a .045" Holley jet 
> will do
> FINE--at the HIGH point. It's utterly astounding how FAST a LOT 
> of vapor
> will go through an orifice that size !!
> 
> Greg
> 
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