[Diy_efi] Re: Minimalist micro based EFI ?

[Toyota Supra]

completely agree! very well explained points






From: Mike <erazmus at iinet.net.au>
>Reply-To: List for general do-it-yourself EFI talk <diy_efi at diy-efi.org>
>To: List for general do-it-yourself EFI talk <diy_efi at diy-efi.org>
>Subject: RE: [Diy_efi] Re: Minimalist micro based EFI ?
>Date: Wed, 12 Mar 2003 00:04:38 +0800
>
>Yes true :)
>
>Well articulated,
>
><sigh>
>
>rgds
>
>mike
>
>
>
>At 09:08 AM 3/11/03 -0700, you wrote:
> >At 11:29 PM 3/11/03, Mike wrote:
> >
> >The basic control theory element you are skirting around here is "dynamic
> >range".
> >
> >The ratio between an engine's minimum and maximum output power is a 
>pretty
> >fair definition of the dynamic range which ANY fuel delivery system must
> >cover.
> >
> >Next question is, how much granularity in fuel flow control rate can the
> >engine tolerate without getting into either emission problems (an
> >artificial constraint), excessive fuel consumption, including plug 
>fouling
> >and/or bore washing (valid concerns) , or detonation (a very real and
> >immediately expensive concern).
> >
> >With a boosted engine, the engine's dynamic range is generally wider, and
> >the higher the boost level goes, the wider the dynamic range gets--so 
>more
> >precision (more bits) MAY well be necessary in measurement of inputs
> >critical to controlling the fuel flow rate fpr boosted engines without
> >getting into excessive fuel control granularity.
> >
> >In fact--the need for more precision in fuel metering may well increase
> >_geometrically_ with boost, since boosted engines are so much more
> >sensitive to detonation than NA engines are !
> >
> >Greg
> >
> >>Yes Mos, but not from the perspective of a design decision to
> >>run an engine over a certain power come boost range...
> >>
> >>ie. A Gen III 5.7L V8 uses a MAF sensor 5v max output, 300Kw
> >>
> >>A RB30 N/A puts out 120 Kw and uses a different MAF sensor also
> >>with a max 5v output.
> >>
> >>Case 1 above at say 100Kw flow has less MAF voltage than the
> >>case 2 with 100Kw flow as its a sensor sizing throat/voltage issue.
> >>
> >>So clearly the sensor is chosen for the range and the a/d resolution
> >>is chosen under some other metric, other than the difference in
> >>vintage between the 2 samples above, is there a compelling reason
> >>the 5.7L V8 *needs* higher resolution if emissions is not an issue,
> >>
> >>rgds
> >>
> >>mike
> >>
> >>
> >>
> >>At 02:06 AM 3/12/03 +1100, you wrote:
> >>>On Tue, 11 Mar 2003, Mike wrote:
> >>>
> >>>> At 01:38 AM 3/12/03 +1100, you wrote:
> >>>> >> <cough> I dont see how boost has anything to do with the number of
>bits.
> >>>>
> >>>> So now you are saying air flow voltage is related to boost pressure
> >>>> rather intimately ?
> >>>
> >>>There's no standard (that I was referring to). I was referring to MAP 
>and
> >>>atmo - hence 5V/1bar (yes, very generally). As another poster stated,
> >>>there's 5V/3bar (and also 5V/2bar).
> >>>
> >>>It doesn't matter what you're measuring, but if your range increases, 
>your
> >>>resolution will decrease if you use the same number of bits, period. 
>Your
> >>>10 bits will not give you the same resolution with 2 bar as they will 
>with
> >>>1 bar.
> >>>
> >>>I was in no way saying that it was insufficient - merely stating that
> >>>boost *can* affect the number of required bits - so yes, boost does 
>have a
> >>>lot to do with the number of bits.
> >>>
> >>>Air flow voltage is related to air flow (obviously), and air flow is 
>very
> >>>intimately related to boost pressure.
> >>>
> >>>Mos.
> >>>
> >>>--
> >>>84 AE86, 90 ST185GrpA, 91 MX83Gr, Sydney, Oz.
> >>>
> >>>
> >>>
> >>>_______________________________________________
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> >>>
> >>>
> >>
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> >
> >
> >
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> >
> >
>
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