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RE: Holley 4barrel TBI, 700 cfm or 454 TB? Q's



At 02:13 PM 6/20/00 -0400, you wrote:
>drill your manifold for port injection..use tpi fuel rails or built your
>own... then use a 600 holly base plate as the throttle body.... guy on the
>list did it with a mopar.. had pics.. real slick setup..
>course you would have to use a 730 :)
>


Heehee :)
I have dreamed of this
the great thing is that I have pretty much all the parts to do it sans the
actual physical manifold work and 730 ecm 
(i have a complete 87 tpi setup.. fuel rails, injectors, harness.. bah, all
the goodies)

Hmmmm...... really how hard would that be? and that would be much friendlier
to forced induction.. heeh

the only thing im afraid of is going from one setup that doesnt work right,
to another setup that doesnt work right

 I havent messed with it much but thats out of frustration since Ive simply
run out of ideas. I last tested the pump at a 1.5 psi pressure drop at
4500-5000 rpm.. which from what I understand is totally acceptable (my car
is running out of gas at 4000) I even verified the adresses in the FL2 map
using a hex editor (double checking my program) seems to be all right on.
For all intents and purposes i should be drowning the motor up there what
with the 40% increase in ve ive built up to.. yet its not happening.

whatcha think?

Unless I dream up of something great that i hadnt thought of before.. or
someone suggests something of equal greatness shes probably getting one of
them carburetor things within the next two weeks. 

Pablo





>-----Original Message-----
>From: olbap [mailto:olbap@mail.mia.bellsouth.net]
>Sent: Friday, June 16, 2000 7:19 PM
>To: gmecm@diy-efi.org
>Subject: Holley 4barrel TBI, 700 cfm or 454 TB? Q's
>
>
>Hey all,
>
>My cars WOT is tuned really well with the stock throttle body now, managed
>to do it in a day after I discovered the prom editing program had a glitch
>in the main spark table (was always running like 26 degrees total timing
>before.. nowonder it ran like caca). It runs pretty good, but the motor is
>seriously choked, by 4300 rpm its done building power in first gear, and by
>5800 rpm im seeing around 2.5" of vacuum at WOT. (the power band is almost
>diesel motor-esque)
>
>Obviously I need a bigger TB, I thought surely the 670 cfm would feed my
>motor till I discovered at 1.5inHg it probably flows just under 500 cfm
>which im not sure will be enough to feed the top end monster this motor was
>built to be.
>
>My other option is a holley analog (doesnt have an IAC motor)   4 barrel TBI
>unit, with 65 lb injectors, brand new for 175 bux.  I like this one because
>it surely will feed my motor since its measured at 1.5inhg (not 100% sure on
>that but I think so) also because this should feed the 350 or 383 im
>planning to build next eventually. I can also run it withoutany adapters,
>andstill have hood clearance to experiment with spacers. The only problem is
>wiring the injectors It seems. Ive heard that wiring them in series can
>cause erratic performance of the second injector in line. 
>
>I noticed a while back that my ecm seems to have four wires going to the
>injectors.. two of which tie back in to the wire next to it. Its my
>understanding that the ecm simply uses these wires to ground the injectors
>and this is how it controls them. 
>
>So I guess my questions are A) Can the 454 TBI unit really feed my motor? I
>want this thing to just rip from 5000-6000 like I felt it do with a holley
>600 cfm carb
>B) If not, are the things ive heard about wiring theinjectors in series true
>on the 4 barrel?  If so, how hard would it be to fashion a powersource
>forthem, and can i just use those two extra spots on my ecm to control them?
>(assuming my understanding of how the system functions is correct)
>C) Will running sans IAC motor have any real bad effects other than just a
>little sacrifice in idle 'driveablity'?
>
>
>Any and all opinions (good or bad) welcome
>
>Pablo
>
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