Water injection (was: Re: fuel cooling intake air)

[Bruce Plecan]

> I have been watching this thread. I was wondering if you might be a bit
> more specific about your application.

87 Buick GN,  3.8L, Auto, engine mildly hotrodded pocket porting, big
downpipe exhuast, fuel pump, Should be a easy to run 12 sec 1/4 mile ET car

Diesel, 436 CID, very carefully put together, 60 PSI of boost,  uses about a
gal of water every 30 secs at WOT.  200PSI WI, and very finely mists the
Water.  We run right at 2:1 fuel water.  Mechanical Injection pump, so
far....

 I have a feeling that the needs of
> a spark ignition engine at high rpm might be different from a highly
> boosted diesel.

Not that I've seen.

 I am wondering if at full boost you manage a
> stoichiometric air fuel ratio (or fuel rich?) with the diesel, or are
> you still very fuel lean as most normal diesels are.

Leaving the line the plum is probably 6-8' in diameter, and 50+' tall, so no
we're nothing like you'd imagine a normal diesel is.

And do you have
> control of injection timing with respect to manifold pressure?

No

>  I suspect that cooler combustion temps might be a good thing with a
> diesel if it it still fuel lean of stoich, so that you aren't combusting
> piston tops as well as diesel fuel.

Running right our ETGs are just like a SI ICE.

 In a mixture that has very little
> extra oxygen, such as a spark ignition engine, then the displacement of
> oxygen is not such a good thing for making power, as a rule of thumb.
> The point of the turbo was to get more oxygen in the engine in the first
> place, after all. If you are very fuel lean and oxygen rich, then
> perhaps this displacement of oxygen is not such a penalty as in a spark
> ignition engine.

But we're not that lean, we're to the stage of really driving the CR up with
the amount of fuel and water were adding.  We're also running, 18:1 CR,
instead of the more common 16.

 But one could argue that it serves a similar function
> as EGR at that point, by reducing peak combustion temperatures. Which
> brings us back to why bother trying to force the air in the engine if
> you only want to displace it with an inert gas or water vapor.

Mr Harris took care to explain that earlier.

>  I might also say that the point of spraying the water at the
> intercooler probably winds up producing water vapor, not puddles, if
> done correctly.

In fooling around with the Wi, and various high pressures, the mist really
wasn't having that much of a cooling effect abainst ones skin, like you'd
imagine.  We were working outside in 90+ temps, and you'd tought if would
make a huge difference.

I've watched and seen how much water it takes to cool an air to water
systems water radiator off.  I takes a bunch of water to make any real
difference.  Granted these are 4L engines, and just around 400-450 HP.  To
really make a drastic difference it going to take throwing, a serious amount
of water at it.  Spraying a mist into anything means it will accumulate on
those surfaces, and drip down.

 The commercially available systems I have seen try to
> evaporate the water in the air just ahead of the intercooler. Whatever
> is left probably boils off. Not saying that others aren't different,
> just what I have have seen.

Who makes that system?.
Grumpy


>
> -Seth
>
> Bruce Plecan wrote:
> >
> > >This is as much as I
> > > want to disclose here.
> >
> > Gee, thanks,
> >
> > > That said, this game is not going to lead you nowhere. Turning back
> > > questions will not make your point.
> >
> > Sure, it did, least you answered a few direct guestions.
> > I now also know to expect sand bagged answers, from you.
> > You want to just play games, instead of discuss things, or think you got
all
> > the answers fine, I'll play the game.
> >
> > > However, I still stand firmly behind what I said: if you let the water
> > > evaporate before it enters the engine, you displace oxygen, and no
matter
> > > how little, this is a bad thing.
> >
> > What is water made of?.
> > Ah,
> > but you didn't say in a reactable form.
> >
> > >Also, water do nothing more than prevent
> > > detonation, just turning on the water jets does strictly nothing to
your
> > > torque output.
> >
> > Haven't seen anyone claiming that. (unless the motor already is
detonating,
> > then there will be gains) (diesel applications, again rears it ugly
head,
> > and your not addressing those).
> >
> >  You can however use more spark advance if required, or more
> > > boost, and from that comes the gain.
> >
> > Fuel is not an element in this, hmm, odd to my way of thinking
> > Advance ignition timing in a diesel, who'd thought
> >
> >  If cool air is what you want, you must
> > > increase the efficiency of the intercooler, spraying water on it being
a
> > > popular option.
> >
> > AGAIN, THIS IS ILLEGAL in some forms of racing.  They (the rulers makes)
in
> > some forms of racing consider it dangerous to spread liquids on the
> > track!!!.   I just as a matter of common sense don't want to be racing
on
> > asphalt, will some one spraying water on the track.
> >
> > BTW, how do you keep any water from evaporating in your system?.  I mean
if
> > it's such a bad thing, in your opinion.  Would mean that, the whole
system
> > would have to be at jus over 32dF, or is there some error in your
statement
> > "you displace oxygen, and" yada yada, or is a gross over statement of
> > fact...
> > Grumpy
> >
> > > Axel
> >
>
> --------------------------------------------------------------------------
--
> > To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the
quotes)
> > in the body of a message (not the subject) to
majordomo at lists.diy-efi.org
> --------------------------------------------------------------------------
--
> To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the
quotes)
> in the body of a message (not the subject) to majordomo at lists.diy-efi.org
>

----------------------------------------------------------------------------
To unsubscribe from diy_efi, send "unsubscribe diy_efi" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org