EFI fuel pump and water.

[Bernd Felsche]

Bruce Plecan tapped away at the keyboard with:

> > You might want to look at using high-velocity air to shear the water
> > into a mist. You may be able to bleed some of your turbo-output
> > (pre-intercooler so you still have a higher pressure) to an
> > air-nozzle, then use a venturi-suction effect (Bernoulli) to feed in
> > the water and to cause it to mist.

> If I understand what your saying:
> Your basically making a carb venturii to atomize the fuel.  Knowing what
> that looks like compared to the high pressure nozzle arrangement, there is
> absolutely no contest.  The High PSI system leaves a fog, it's almost cloud
> like.  Which on the vaporization side is what I want.  Also, the discharge
> from the turbo say 20 PSI, the pressure drop across the I/C what maybe 2-3,
> what real flow would that generate?.  If you add the water pre-turbo all it
> does (other then kill the compressor, if more then the modest of amounts),
> the centrifigal force throws it to the walls anyway.  Don't see where any of
> this works.

Sorry for not explaining it too well; the water is misted in after
the I/C with some bleed air taken off ahead of the I/C then
"boosted" by a secondary (air) pump. You're obviously getting a
different picture due to my using the "carb." word.

The misting principle is similar to an air-brush. That doesn't
create a super-fine fog, but it's a much finer mist than with a
low-pressure water jet running at similar pressure. An air-brush
uses high _velocity_ to achieve the effect. The pressure of the gas
in that case is quite low.  Often less than 100kPa (relative).

> > It should be easy enough to modulate the amount of water by
> > restricting its flow using a low-pressure valve in the water suction
> > line. Just keep the bleed air bleeding.
> > That removes the need to use a high-pressure water pump to achieve
> > the fine mist.
> 
> For all the custom machining, fab work, the pump is tons easier, and DIYer
> friendly.
> Please note the wording.

The low-pressure valve for the water feed can be made from readily
available materials. Stainless feed-tube, polymer valve body and
piston with electro-magnetic actuation. If you only need the "WI"
for a short time and/or low duty cycle, then a gas-bottle could be
used as the source of gas; a commercially-available solenoid valve
on the bottle would also do the trick.

>  Tricky bit would be to ensure that you have enough
> > pressure differential between the bled-air and the manifold for it
> > to work. A secondary-air pump may be useful to ensure a higher
> > pressure, if it'll cope with the high inlet temperature (I don't
> > know the characteristics of such pumps to any detail.)
> 
> This is now, ME overkill, IMHO.

Fair enough. But if, as you say the I/C drops only a couple of psi,
then you do need the pressure differential above manifold to create 
the high-velocity jet.

> > The hotter air would also assist in creating water vapour to reduce
> > the likelihood of water erosion around critical areas such as
> > valves.
> 
> What hotter air, and what valves.

The air bled from the turbo output ahead of the I/C is hotter and
the (intake) valves in the cylinders. Again, sorry for not making that clear.

> > If you're metering air flow, then you'd need to bleed the air
> > downstream of the meter.
> > That's just an idea. It may work. Feel free to jump in and knock the
> > idea on the head.
> > Bernd Felsche - Innovative Reckoning
> 
> Grumpy
> LGICOCSH,HQT

-- 
Bernd Felsche - Innovative Reckoning
Perth, Western Australia
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