747 & 4cyls

[Bruce Plecan]

> >Ok, I've been reading some more about this stuff now.  I have another
couple
> >questions.  Can the 747 be used with a 4 cyl?  And, can it be used with
high
> >impedance (12-16 ohm) injectors, such as the PI ones on my soob @ 260
cc/min
> >each?
> Hey Bruce, can you help Andy out with this one; I don't have my main
> machine in hand yet, where I kept the notes on what kinda injection
> style and cyl-counts are supported by what.

There's a problem here.
The TBI is gonna want to fire the injectors per the factories strategy and
that is based on P+H injectors which can operate jus fine at about 1/2 the
pulse width of a Sat one.
So that is a big glitch.

Other thing is MAP is going to be all important on this. (MAF is way too
unreliable for aero use, IMO)

Forgot to ask, DIS or Distributor?.

Haven't been ignoring thread just got hot irons everywhere, and been tip
toeing around tryin not to get burnt...

Injector sizing may be an issue to.

Have you taken a gm MAP sensor aloft and recorded the output with a 5v
source / ground, might need to know rather early how this looks.

While a stock engine might idle at 40 K/Pa at sealevel, and reach 96 out of
98 K/Pa at WOT, what is ambient K/Pa at altitude

This is something where you might just want to get a full time baro input,
and that would have to be with Johns 730 stuff.
   The more I think about it the Baro is probably gonna be a mandatory item,
or you'll be futzin with the AFR all the time.
Bruce

Just gotta think on this more.


>
> >What I am looking for is something that can utilize some of the stock
Soob
> >stuff.  I already tested the TPS and it gives the same signal as the GM,
so
> >I can use my Soob TB.
>
> Hey, that's GREAT. Not having to hack on the stock throttle body is
> really a help. On the subject of injectors, most all the GM ecms can
> drive gangs of SAT injectors (that's what you have on the EJ-22, not
> P&H like on the turbo EA-81), so you should be fine there.
>
> Did you find some likely candidates for where to tap the induction for
> MAP sensors, Andy? Just wondering if some of the old plumbing would
> actually be useable.
>
> Also, would anyone onlist be willing to take a stab at explaining how
> the analog stuff on the memcal is used in limp mode, electrically
> speakin? The only thing I've heard so far is the resistive network
> sets the cyl-count, but that's about it as far as my understanding
> goes.  Just exactly what else does the memcal provide to the ecm in
> limp mode, and how does the ecm use it. In short, say more please!
>
> Gar
>
>
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