MPI, TBI, and TrunkFI and megasquirt musings

[James Northrup]

I was having a freindly devil's advocate debate with a carb enthusiast
recently, the subject of drilling/tapping injectors into a perfectly usable
edelbrock intake was just too much flamebait to pass up.

for atomization it just seems that distance is better, and better
ultimately==mpg.  thus drilling for MPI seems like its more of a "waste"
than just accomodating a TBI configuration.

1st question: will megasquirt accomodate a TBI configuration?

this same person I was debating with had an encounter with a ford prototype
project which was basically a tiny 2bbl carb mounted in the trunk of a
t-bird (early 70's 351) which had so much runner distance through a tube
that it would reach some 50+ mpg highway at the cost of performance;
atomization was supposedly that good.

2nd question: can megasquirt accomodate a multi-stage behavior model the
likes of which allow for a TBI off-idle application with a full-on MPI
personality when its time to gas it up?

3rd question: Am i the only one who thinks the Tuarus SHO intake is a sexy
bitch with its dual intake runners?
http://www.spmotorsports.com/img/taurus_engine.gif
3a) would megasquirt meet the needs of dual intake runners with thier own
special purposes?

i digress.  I concede there is no good reason to replace a working carb with
a working MPI or a working TBI configuration.  common sense wins out,
there's no radical gain but adding software to a hardware solution.

so what if we push the envelope a bit to make a dual-behavior intake, with a
bit of long-runner (really long) high-atomization idle vapors and full-on
MPI?

for instance, perhaps we run two megasquirts in tandem, one controls the
off-idle TBI injectors #1(maybe #2?) and the other controls the richer needs
of all 8 port injectors.  the maps can phase in and out of each other's
territory as needed.  if the TBI was on the side of radical mpg efficiency
we might want a small time coefficient to transition off of the MPI system
to full-on 1-2bbl TBI input for cruise control at high vacuum.

cabling "primary" and "secondary" fuel intake butterflies and channels would
be exciting in and of itself to design.  a cyclical gearing on the primary
could open and then close again as the "secondary" big bore takes hold in
the higher reaches of the pedal.

this somehow seems worth doing.  just to say its been done.  to prove or
disprove an old rumor about atomization carbs and get giggles from the gas
mileage on the way to and from the drag strip.

i see alot of interest in both high-end and fuel efficiency in here but
apart from the same old port injection systems, what geometry and airflow
experimentations are ppl willing to undertake?  the biggest part is
liberating the ECM from detroit and tokyo, the easy part would seem to be
hammering and drilling to affect air velocity and charge cooling.  turbo
enthusiasts find no shame in stringing a few feet of pvc pipe to channel air
through this and that fin and vane; where are other examples of normal
aspiration creativity?



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