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water injection



Scott,
Hey, you told us to poke holes...
    Keep in mind that discharge pressure of a centrifugal (windshield wiper) pump is non-linear.
Change in rpm = change in pressure squared. While it is also true that in a centrifugal pump flow is
proportional to motor speed, this doesnt apply since the pump is running at near static head
(discharge pressure). Also in a dc brushed motor you run into yet another non-linearity with
changing voltage vs. rpm. This means that with a very slight drop in voltage you will rapidly drop
to below 10 psi discharge pressure.
    Yet another 'hole' is that injectors designed to work at 15 psi may start to 'dribble' at <10
psi.
    The best way to go proportional controller is to do some sort of pulsed injectors or something.
Al

----- Original Message -----
From: "Scott F. Williams" <sfwilliams@comcast.net>
To: <calimus@techography.net>; "Scirocco List" <scirocco-l@scirocco.org>
Sent: Friday, March 22, 2002 10:20 AM
Subject: RE: water injection


> Guys, I originally started this thread in respect to my own interests with
> nitrous oxide tuning. However, anyone with a pending turbo project should
> also take note...
>
> Anyway, I learned a few more things about doing this water injection
> project. Speaking yesterday with George Spears, former president and founder
> of Spearo Intercoolers (now sold to Turbonetics), I learned that:
>
> a) Mixing a 50/50 methanol and water cocktail increases the knock
> suppression effect and may shoot inspring flame balls out the exhaust
> between shifts. Yeeyah!!!
>
> b) Our 2.0l-sized motors will be happy with about 50cc/min water flow per
> cylinder.
>
> c) In a normally aspirated situation, there is no need for a powerful water
> pump. With a properly chosen flow-rated spray nozzle, atomization will be
> fine. (The best system on the market, Aquamist, uses a 7bar pump for turbo
> use.)
>
> A simple windshield washer type will work fine if the water bottle is
> located close to the engine. If not, then two of these pumps in line will
> work fine. Again this is for normal aspiration. Turbo guys will need
> something more powerful.
>
> d) The real key to this job seems to be finding the correct spray nozzles.
> They have to atomize properly at about 15psi and flow just 50cc/min. The
> research continues!
>
> P.S. If I do this, I'll probably base my system off of the Spearco
> Injetronic system. By tapping into the tachometer signal, the system varies
> the amount of voltage sent to the water pump based on rpm. So, actuation is
> not just an on/off affair. Nice!
> --
> Scott F. Williams
> NJ Scirocco nut
> '99 Subaru Impreza 2.5 RS
> Mazda 323 GTX turbo "assaulted" vehicle
> Golf GTI 16v "rollycar"
> ClubVAC: "Roads found. Drivers wanted."
>
> Check out our rally team's website!
> http://www.usrallyteam.com
>
> > -----Original Message-----
> > From: Brian Haygood [mailto:scirious@hotmail.com]
> > Sent: Thursday, March 21, 2002 12:31 PM
> > To: Scott F. Williams; Scirocco List
> > Subject: Re: water injection
> >
> >
> > Hey Scott, I have a great idea!   Why not get a NOS bottle and fill that
> > with water for your injection system.  That would be PHizAT!    Then you
> > would have some real respect wherever you went  (OK, maybe not from anyone
> > who has enough brains to tie his own shoes, but the boy racer/civic types
> > would love it).
> >
> > ha ha ha ha ha.  I amuse myself today.
> >
> > I'd also like to share with everyone that, having graduated in December I
> > went from professional student to officially unemployed, but today I got a
> > real job.  They even pay money, not just course credits or
> > something.  It's
> > a good day.  I'm looking forward to calling in sick to work on my
> > Scirocco,
> > so I can officially be just like everyone else on the list.  :)
> >
> > On a less sarcastic note, I don't see why water injection wouldn't do the
> > trick for you, Scott.  Could you just use the supply of windshield washer
> > fluid and keep that cleaned up and filled with distilled water or
> > something?
> > I guess that depends on how much NOS you plan on spraying.  If you need a
> > good water bottle, you might look the later cars.  My '95 Passat
> > and '00 GTI
> > both have 5 liter washer bottles, with the motors nicely nestled
> > inside/alongside them.
> >
> > For spray nozzles, maybe you can use needle jets from carbeurators?  There
> > is certainly a huge variety of those in the world, and some at
> > least can be
> > installed in a threaded hole in the T-body's.  They would probably drip a
> > few drops after turned off, but that's probably OK, isn't it?
> >
> > You would drive yourself nuts trying to rig some kind of injector on each
> > body, I think, especially when you have already squeezed in fuel, NOS, and
> > pressure taps to each body.
> >
> > BH
> >
> >
> > ----- Original Message -----
> > From: Scott F. Williams <sfwilliams@comcast.net>
> > To: Scirocco List <scirocco-l@scirocco.org>
> > Sent: Thursday, March 21, 2002 8:46 AM
> > Subject: water injection
> >
> >
> > > Hey, I think I'm about to blaze some new trails here, but I figure I'll
> > ask
> > > anyway. Does anyone on the list have any experience with water
> > injection?
> > > I'm rethinking my plans for a fuel cell holding racing gasoline for use
> > when
> > > I activate my nitrous system.
> > >
> > > There's a lot of redundant plumbing and electrical controls
> > that I'd have
> > to
> > > rig. -more weight and more stuff to go wrong. I'm thinking that a well
> > > implemented water injection system would do the trick just
> > fine. I figure
> > > that I could activate in two situations: a) via whatever signal triggers
> > the
> > > nitrous, and b) whenever knock is detected.
> > >
> > > I could mount the water tank pretty much where ever I'd like. I
> > figure I'd
> > > put it somewhere around the battery (in the back) with a couple of small
> > > windshield washer pumps run inline to keep the pressure and flow up. The
> > > minor plumbing challenge would be rigging a distribution block and lines
> > to
> > > each throttlebody. And, of course, I'll have to find some spray nozzles
> > with
> > > a nice atomization pattern and the correct flow.
> > >
> > > Babble... babble... I'm on Spring Break!!!! :^)
> > > --
> > > Scott F. Williams
> > > NJ Scirocco nut
> > > '99 Subaru Impreza 2.5 RS
> > > Mazda 323 GTX turbo "assaulted" vehicle
> > > Golf GTI 16v "rollycar"
> > > ClubVAC: "Roads found. Drivers wanted."
> > >
> > > Check out our rally team's website!
> > > http://www.usrallyteam.com
> > >
> > >
> > >
> > > _______________________________________________
> > > Scirocco-l mailing list
> > > Scirocco-l@scirocco.org
> > > http://neubayern.net/mailman/listinfo/scirocco-l
> > >
>
>
>
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