[Diy_efi] pressure vs flow?

[Tlsalt at aol.com]

Brian Michalk wrote,  

I want to run my EFI system at 50psi, and use the CIS injectors as backup.
I like the atomization of the CIS injectors, but if they crack open at 30
PSI, I don't think I'll be able to get enough flow at 50PSI unless I crank
up my rail pressure to something closer to 90 or 100.  The only thing I
don't like about that is the electric fuel pump really eats a lot of current
making 100psi.

Again, this is for an airplane with two injection systems.  The EFI was
easy, the backup requires some more research.

So, back to the CIS issue.  The only thing that makes squirting possible is
pressure, therefore the plunger causes some sort of pressure variation. 

Hello Brian,

I think what you are trying to do is possible, but it will be difficult to 
vary the fuel delivery without using the fuel distributor.  The opening 
pressure limit is just to prevent bleed down after the engine stops, if there 
is air flowing into the engine, the fuel pump is on and the injectors are 
constantly spraying.  There is no "injector off" time. What about using a 
separate CIS pump and some kind of manual flow control valve for a limited 
speed range?  Kinsler barrel valve with a cable? 

Paul Saltwick

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