Nother thought

[timsiford at hushmail.com]

>I think theres enough info here for my concerns to evaporate.

You were concerned about lil 'ol me?  j/k  Thanks for lookin' out.  I CANNOT 
believe you are getting away with 22lb injectors on a 383 with a ZZ4 cam. 
 What heads are you running?  At what RPM are you shifting?

Tim

>
>----- 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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