[Diy_efi] CIS EFI via Fuel Pump PWM

[Marc Reviel]

>What I am saying is,  (in more detail and with slightly different
>words) the rotational inertia of the fuel pump rotor is a factor in
>maintaining pressure stability - it would have to be taken into
>account in a PID algorithm and a switch mode power supply that could
>dump a fair (transient) current into the (high pressure) fuel pump
>would be of advantage versus a (conventional) PWM drive off the
>(normal) battery voltage...

 I would consider paralleling two small, low(est)-inertia pumps. Plus, 
run them from higher than batt voltage (simple ~30 amp ~20V boost 
regulator).  Never need to exceed 12V RMS for more than 1/10 sec or so, 
but you'd definitely maximize the response of the system (reduce LR 
time-constant).
 I think that bleeding off pressure for fast throttle closures probably 
wouldn't be necessary in most cases.  But a single large electrical 
injector with it output returning to the tank would do it in a pinch.
 Adding much more complexity than this would reach point of diminishing 
returns, making conventional PWM/EFI look better (imho). ;)

 I really admired the CIS systems for years.  I had built several race 
engines with the Porsche 928 CIS systems.  Worked very, very well, and 
was extremely reliable (just have a good in line fuel filter, and that's 
all).



Marc Reviel
PowerLogix, http://powerlogix.com, co-owner/CTO
Forced-Air Systems of Texas, http://www.f-a-s-tonline.com, co-owner



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