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

[Axel Rietschin]

> > 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?.

..water, an inert substance, as long a internal combustion engines are
concerned. And that water is expelled at the exhaust as.. water, too, or H2O
if you prefer. All of it.

> >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).

It's easy to observe, especially on a dyno. In my own experience, just
turning on the jets didn't change the torque output at all. I believe no one
will claim to have gained anything by just injecting water without making
any other change.

>
>  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

Well, more boost means more fuel, hopefully. Your ECU is supposed to take
care of that since an encrease of boost will show up at the AFM or MAP
sensor, and water has nothing to do with it, unless, injected 'early', that
water has evaporated and cooled down the charge (I don't deny the cooling
effect, I say the benefits of a lower temp, density wise, is lost because of
dilution). The ECU will see a lower air temp and add more fuel, which in
this case would be a mistake since there is no corresponding increase in
oxygen (your turbo is not going to swallow any more air because you inject
some water after it, right?)

> Advance ignition timing in a diesel, who'd thought

Obviously, spark advance refers to SI engines. Your diesel engine is
effectively not concerned by this aspect of thing but the point is minor.
However, in both types of engines, there is a lot to be gained if a normal
combustion can be maintained with more boost or compression ratio. As soon
as you get end gases detonation or, worse, runaway detonation (also referred
to as preignition) the game is over.

>  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.

Why "again"? I don't recall you said it before (sorry if I missed it). Also,
you suggested cooling the IC with NOS, a substance definitely not allowed in
FIA rallying, water however, is allowed there.

> 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...

It is reasonable to think that if you inject close to the valve, less water
will evaporate outside of the engine, thus less oxygen will be displaced. In
contrast, injecting before the IC obviously gives much more time for the
water to turn to vapor and thus displace more oxygen.

Axel



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