Partial success - final take

[Bruce Plecan]

You've got alot more time in this then I, and just a couple thoughts of mine
are:
I think that the adaomization that you speak of is true, and I contend, that
it greatly helps the fuel to vaporize when it does hit the manifold walls.
  Also, in the newer stuff there are alot of mono blades, which greatly
reduce the air velocity, so that the fuel in suspension can "bend around"
easier with out falling out of suspension.
  In oem applications, as installed, the cone is way too smal in diam when
it hits the blade and then all runs off to the low side making this shearing
effect more critical, since things are so baddly puddled.  How ever raising
the injectors vastly reduces this problem, and lessens the effectiveness or
criticalness of the butterfly.
  Kinda like the pumping losses with EGR, great theory, just I've never
found them to have a measurable advantage.
   Also, in the particular engine referenced it has about the worst ports in
the intake imaginable.
Siamesed, with a tiny plenum (maybe 6 CID on a 50 CID eng), manifold
Bruce





> Yes, the small areas between the TBI throttle blade edges and the bore
walls
> play a HUGE role in fuel atomization in TBI setups.   The small areas
> promote extremely high localized air velocities at anything less than WOT,
> and associated vortices below the blade(s),  which promotes vigorous
mixing
> downstream within the plenum(s).  Also, the sharp machined edges are
> intentionally left in place to promote further promote shear of the liquid
> fuel.
>
> Your TBI injectors will have a somewhat wide spray angle (70 degrees?),
> originally intended to spray the fuel charge "into" the small annular
> openings between the blade(s) and the walls, while intentionally missing
the
> blade during its fullest arc.  In the absence of a throttle blade  (ie:
you
> remove it), the fuel spray from the TBI injectors will simply splat
against
> the bores, drip down, and then ??possibly?? re-entrain with the airflow to
> some degree within the bowels of your wet manifold.
>
> If wanting to attempt a bladeless quasi-TBI blow-thru fuel delivery
> mechanism for a wet manifold & dry S/C application, then perhaps think
about
> installing PFI injectors in place of the TBI injectors downstream of the
> S/C.  This will take a fair bit of custom machining, and a fair bit of
> research, as there are many different "plumes" available with individual
> PFI's.  Cone angles tend to range from 60-12 degrees, and the patterns can
> be anything from hollow-conical to pencil stream.
>
> What you have proposed is not new, but needs a fair bit of research to
work
> right.  Ideally, true port fuel injection is the best way to go in
> conjunction with the throttle upstream of the S/C.
>
>
> Walt.
>
>
>
>
>
> > Now does anyone know, if removing the throttle blade out of the tbi will
> > have any effect on the delivery of fuel in the tbi, is the shear of the
> > throttle blade used for fuel vaporization in these systems ?
> >
> > Dan  dzorde at erggroup.com
>
>
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