ray
i will check out all those links. thank you.i guess my thought is,even with modest mods (exhaust,air intake)are the factory settings in the computer able to make the best of said mods without some sort of reprogramming? i haven't looked at your links yet so maybe after doing so i will understand more about "speed density systems"my next question is to the group.have any of you reprogrammed for fuel economy or performance or both? i would like to stick to the 4.7 on this subject but all experiences too.thanks again ray.
mike
--- On Fri, 9/17/10, Ray Block <BPracing@wowway.com> wrote:
> From: Ray Block <BPracing@wowway.com>
> Subject: RE: DML: Re: K&N fipk
> To: dakota-truck@dakota-truck.net
> Date: Friday, September 17, 2010, 8:33 PM
>
> Mike, If you really want something to think about
> concerning EFI systems,
> check out www.fastmanefi.com. Rich Nedbal
> is a well respected EFI expert,
> author, Mopar guy, and regular poster on
> Moparts.com. At this link,
> www.fastmanefi.com/TechDownLoads.htm you can download
> several tech articles
> he's written. Pay particular attention to "All
> you wanted to know about
> EFI but were afraid to ask chapter 2". In
> case you can't open Word
> documents, I've enclosed some excerpts concerning the
> various types of EFI.
> -------------
> "Speed Density Systems:
> A Speed Density system merely looks at how far the throttle
> is open, the
> intake manifold vacuum, and RPM. An SD system can
> obviously deduce the
> engine load, just as you could, by looking at these
> parameters. For
> example, if the throttle is open, say past 50%, and the
> intake manifold
> vacuum is low, and the RPM is only 2500 RPM, wouldn’t you
> say this engine is
> being loaded? And if the throttle was closed, and the
> resultant manifold
> vacuum was high, yet the RPM is 3500 and slowly coming
> down, wouldn’t you
> say that you just backed off on the throttle from a high
> speed cruise and
> are coasting down?" (I'm leaving out the
> Volumetric Efficiency graphs he
> shows)
>
> "Alpha-N Systems:
> In cases where an engine’s camshaft is so radical that
> very little vacuum is
> produced, the change in vacuum may not change enough to
> reliably compute
> fuel requirements. In these cases the VE table above is
> replaced with actual
> injector pulse widths. This approach is much harder
> to work with, but for a
> race engine where all you really need is to start, idle
> (sort of) and full
> throttle, Alpha-N can work.
>
> Mass Air Systems:
> In theory, if the ECU knew the mass of the incoming air it
> could do a better
> job of computing the engines fuel requirements.
> “Mass Air”, as it is
> called, would automatically take into consideration
> humidity, altitude, etc.
> In addition, less human tuning would be required because as
> long as the ECU
> program knew the characteristics on the engine, together
> with the mass of
> the air, the system could self adjust.
>
> Most of today’s OEM EFI systems use mass air for this
> reason. Why aren’t
> all the aftermarket systems Mass Air? Mass air
> sensors use hot wires in the
> throttle body. These wires have to be short to not be
> fragile. This limits
> the diameter of the throttle body. Dual throttle
> bodies add a level of
> electronic complexity and equalization that no one
> wants. If you want a lot
> of horsepower with a mass air system you have to work at
> it, and you still
> have to start with a system that is optimized close to what
> your engine
> needs.
>
> Summary:
> Most aftermarket EFI systems use Speed Density because
> it’s easy to program,
> fairly cheap, and works very well with any size
> engine. Alpha-N is only for
> racing. Mass Air is very good for smaller engines
> that don’t need larger
> throttle bodies."
> -----------
> Hope you found this interesting, Mike. In a nut
> shell, there's nothing
> wrong with the Speed Density systems Mopar
> uses. You would be surprised
> how far you can go with engine mods on a emissions legal MP
> PCM if you
> choose your parts carefully. Just look at
> the mods I've made to my Dak at
> the link below....and mine is considered mild compared to
> several of the Dak
> racers I know who are way quicker than I.
>
> Ray
> http://www.dragtruk.com/ENTRIES/20KM1FD2KWBP.html
>
>
>
>
> > -----Original Message-----
> > From: MICHAEL CABE
> >
> > just something to think about,speed density systems vs
> mass air flow.
> >
> > --- On Fri, 9/17/10, Ray Block <BPracing@wowway.com>
> wrote:
> >
> > > From: Ray Block <BPracing@wowway.com>
> > > Subject: RE: DML: Re: K&N fipk
> > > To: dakota-truck@dakota-truck.net
> > > Date: Friday, September 17, 2010, 6:26 PM
> > >
> > > > -----Original Message-----
> > > > From: MICHAEL CABE
> > > : Re: DML: Re: K&N fipk
> > > >
> > > >
> > > > jon,
> > > > i found this very interesting.
> > > >
> > http://www.carcraft.com/techarticles/electronic_fuel_injection/index.html
> > > >
> > >
> > > Mike, while I'm not Jon, I am curious as to what
> you found
> > > so interesting in
> > > that Car Craft article. ??
> > >
> > > Ray
> > >
> > >
> > >
>
>
>
>
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