Nother thought

[Dave Zug.]

I think theres enough info here for my concerns to evaporate. I was hoping
you considered RPM in the DC calc.  Theres the closing time thing too but I
see you understand.


----- Original Message -----
From: <timsiford at hushmail.com>
To: <gmecm at diy-efi.org>
Sent: Thursday, October 05, 2000 11:02 AM
Subject: Re: Nother thought


> Dave,
>
> Understood.  I'm in class right now but I'll post the PWs that gave me the
> 100% DC later tonight.  I wrote a convenient VB program that I use to
calculate
> all sorts of Automotive data.  The DC is based on batch fire cars where
> 100% DC was equivalent to an injector Pulse Width of 10.0ms at 6000RPMs.
>  I'll post the full formula later.  NOTE:  I didn't consider opening and
> closing time.  Thus, the DCs could be even higher.  I went over and over
> and over swapping out my injectors.  Everyone in MAFB said that I
shouldn't
> need to go higher than 24lb injectors.  Diacom also reported AOK O2
voltages
> at WOT throughout the entire WOT run (0rpms->6500rpms).  I replaced my
injectors
> SOLELY because of the DCs I was seeing.  Many people told me not to
replace
> my injectors ... that the 22lb injectors would be enough.  Diacom
supported
> that.  But, the DCs did not (and I was running 52psi at the rail).  I
upgraded
> to 24lb SVO injectors based on everyone's recommendations.  Well, with the
> 24's I was seeing almost 90% DCs at 6500rpms.  Those injectors were on my
> car for only an hour before I ordered a set of 30's.  The 30's have
acceptable
> DCs ... in the order of 77% at 6500rpms ... and, the car idles great.  I
> have the injector constant set to 33lb/hr in the PROM and I am running
45psi
> at the rail.
>
> I do remember that at 4500rpms my injector pulse width stayed pretty
static
> until up to 6500rpms.  The fact that the RPMs were increasing and the IPW
> remained the same caused the DC to rise substantially.
>
> My butt-o-meter is very inaccurate.  You're talking with someone who
couldn't
> tell too much of a difference after swapping heads/cam.  But, with the new
> SVO injectors (30lb) I noticed a difference in the upper RPMs.  If I get
> to the track soon I might be able to prove it :-)
>
> Tim
>
> At Thu, 5 Oct 2000 10:00:52 -0400, "Dave Zug." <dzug at delanet.com> wrote:
>
> >
> >To clarify, What Pulse width (in Ms) are you calling 100% DC  at 4500
> >RPM?
> >
> >Were your PW's constantly INCREASING as RPM went up?
> >
> >My 383 CI (360hp thereabouts, almost same cam as yours- less flow above
> >5500
> >though, stock lower intake) uses stock 22# and stock FP almost, hits
> >85%
> >static for a BRIEF moment after the shifts. o2's still on the rich side
> >according to GM sensor (093) , and plug condition backs it up.
> >
> >This is not meant as evidence contrary to your observations - just more
> >info
> >to add to the collection.,.. mine and yours.
> >
> >----- Original Message -----
> >From: <timsiford at hushmail.com>
> >To: <gmecm at diy-efi.org>
> >Sent: Thursday, October 05, 2000 9:49 AM
> >Subject: Re: Nother thought
> >
> >
> >> I was running the stock 22lb injectors on my IROC (218cam, AFR heads,
> >MiniRam)
> >> for about 3000 miles before swapping to 30lb injectors.  At WOT I
> >would
> >> reach 100% DC by 4500rpms.  I would continue to shift at 6500.  This
> >is
> >>  great example of how the stock O2 cannot be used for tuning.  The
> >O2
> >volts
> >> were approx 830mV and greater throughout the entire RPM range even
> >though
> >> I was hitting 100% DC.  After switching to 30's I noticed significant
> >improvement.
> >>  The stock 22lb injectors never falterered and still function great.
> >>
> >> Tim
> >>
> >> At Wed, 4 Oct 2000 23:22:33 -0400, "Bruce Plecan" <nacelp at bright.net>
> >wrote:
> >>
> >> >
> >> >Anybody have any info., about the extended effects of running really
> >> >high
> >> >DCs on injector drivers?.
> >> >Just thinking, out loud.
> >> >Just with all the hours of running stuff here, I can't find any real
> >> >reason
> >> >for for the 85% DC, as applied to a street car.
> >> >Just maybe do to worry about a worse case thermal situation, and
> >portecting
> >> >the devices?.
> >> >Or maybe just a ol wifes tale....
> >> >Bruce
> >> >
> >> >
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