[Gmecm] custom retro carb efi lookalike

[David Allen]

That's a nice part. Really looks like a quality system.

The computer really only cares about the injector impedance (Z).  Typically - with Rochester EFI the injectors are low-Z with peak-hold driver circuit in the ECM, and the port injector systems are high-Z with a simple on-off saturated driver in the ECM.  Other than that, the placement of the injectors is irrelevent to the ECM hardware (the computer). 

The tuning is mainly to match the engine's airflow to the delivered fuel. Wether the injector is above or below the throttle plate, this wouldn't matter. What DOES matter is the volume of the inlet manifold which is wetted with fuel.  This is where the injector placement affects the tuning.  The closer the injector to the intake valve, the less acelerator pump shot is required. 

So for this unit, you would need a TBI-like curve for the fuel and acellerator pump shot. I didn't see the injector impednace on that website but the ECM hardware would have to match this.

Hope this makes sense - I am about out of time today!
David


  ----- Original Message ----- 
  From: alan mays 
  To: Gmecm at diy-efi.org 
  Sent: Friday, February 24, 2012 5:45 PM
  Subject: [Gmecm] custom retro carb efi lookalike


              I was checking out the efi retro stromberg 97 from   

        http://www.autotrendefi.com/efi_97.html  its got the injectors spraying just UNDER the throttle blade---  so its not throttle body?

         if the injectors were spraying just above the blade--it would be throttle body injection--and would have to be tuned as such?
          so the setup is technically port injection as long as the injectors are down stream of the blade --by even a inch,  and has to be programmed as port injection--and use a port efi computer?   



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