RPM independence

[Stowe, Ted-SEA]

where do you get GM High-Tech Performance ?

> -----Original Message-----
> From:	Todd....!! [SMTP:atc347 at c-com.net]
> Sent:	Wednesday, May 12, 1999 9:53 AM
> To:	diy_efi at efi332.eng.ohio-state.edu
> Subject:	Re: RPM independence
> 
> Howard the article is in the May 99 issue of GM High-Tech Performance
> 
> And the brand that uses Volumetric and other formulae instead of look-up
> tables is known as Electromotive....  Probably heard of em?  HAHA!??
> 
> Keep me informed of your progress in this matter!
> 
> LATER!
> 
> Todd....!!
> 
> Howard Wilkinson wrote:
> > 
> > Todd:
> >     I would be very interested in reading the article you mentioned.
> > Please let me know if you find it.
> >     My basic thought here is to emulate the working of the Bosch
> > mechanical CIS fuel injection system electronically which would allow
> > it to be modulated by feedback, but still yield a system simple enough
> > to be operated by a very low cost controller.  Injector timing is
> > irrelevant, therefore injector firing rate is also irrelevant within
> > the range above engine RPM.
> >     Perhaps mathematical formulae are not adequate to control fuel
> > delivery.... maybe lookup tables are necessary.  The Bosch mechanical
> > system used a shaped MAF to keep fuel flow which was mechanically
> > controlled in line with the motion of the MAF actuator arm.  This put
> > the mathematical calculation into the profile of the MAF throat which
> > was in effect a computer (a mechanical computer).  It took far more
> > intelligence in my opinion to design this one part than to program
> > look up tables which can be done by trial and error, or by a simple
> > feedback system.  I believe I could sit here and flow chart out and
> > write a program to generate the lookup tables based on feedback, and
> > minimal programmer input.  I'm just looking at different possible
> > approaches to the problem of managing fuel delivery via computer.
> >                                         H.W.
> > 
> > -----Original Message-----
> > From: Todd....!! <atc347 at c-com.net>
> > To: diy_efi at efi332.eng.ohio-state.edu
> > <diy_efi at efi332.eng.ohio-state.edu>
> > Date: Tuesday, May 11, 1999 1:15 PM
> > Subject: Re: RPM independence
> > 
> > >Hello Howard,
> > >
> > >your theory is TOTALLY GREAT and acceptable, and a system has alread
> > >ybeen created, produced, and marketed, and it's gone over wiht a
> > pretty
> > >good fine tooth comb within on eof the laterChecvy Hi po mags dealing
> > >with all of the diff types, makes, and brands of FI for just about
> > any
> > >type engine!
> > >
> > >Will get the name of the mag, I know you already know about the mag,
> > >just maybe not about the article(s) within this specific issue?
> > >
> > >But the basic function of the type system I believe you are referring
> > to
> > >is based upon the use of formulas instead of tables... I think you
> > are
> > >right in line witht the way this REALLY advanced system is designed
> > to
> > >function!
> > >
> > >Will post details later, (mag's at home)!
> > >
> > >LATER!
> > >
> > >Todd....!!
> > >
> > >Howard Wilkinson wrote:
> > >>
> > >> I have given more than a little thought to the possibility of an
> > EFI
> > >> system that operated completely independently of engine RPM.  The
> > idea
> > >> being that as the injectors are batch fired anyway, the timing is
> > >> irrelevant so long as the injectors fire at engine RPM or more.
> > >>     Such a system could be almost entirely MAF based.  The
> > injectors
> > >> would begin at a very short pulse width, and simply increase pulse
> > >> rate up to a set pulse rate where width would be increased
> > thereafter.
> > >> Such a system could be operated based on mathematical formulae
> > rather
> > >> than on look up tables.  A simple equation based on ECT could
> > modify
> > >> the result for cold operation, and a TPS modifier would give
> > >> accelerator pump effect.  Map should not be necessary as air
> > density
> > >> should directly effect MAF output.  An O2 loop would handle minor
> > >> dicrepancies.
> > >>     A lot of the complexity of the common EFI systems comes from
> > the
> > >> desire to fire the injectors once per revolution.  Because of RPM
> > >> dependence, the MAP, MAF, & TPS outputs are meaningful only in the
> > >> context of RPM.  Total fuel delivery per unit time is only directly
> > >> related to MAF.... It is not closely related to RPM, Throttle
> > >> Position, or Vacuum individually as it is to MAF.  The MAF tells us
> > >> how much fuel we must deliver per unit time, but the system must
> > then
> > >> work out the pulse rate based on RPM, and pulse width for that rate
> > to
> > >> achieve the desired delivery per unit time.
> > >>     If we know that x amount of fuel is delivered at Y pulse width
> > per
> > >> pulse, then it becomes a simple matter to determine how many pulses
> > >> per unit time are required to deliver that amount of fuel.  At some
> > >> point pulse rate reaches a max practical limit, and at that point
> > >> pulse rate can become constant, and pulse width may be modified
> > above
> > >> that point to control fuel delivery.  The fewer factors you are
> > >> changing the simple the program becomes.
> > >>     Perhaps this is a simple minded vew of the process, but then
> > I'm a
> > >> simple minded sort of guy.... I am of the "KISS" school of thought.
> > >>                                 H.W.
> > >
> > >
> > >
>