[s-cars] Water injection (rant, long, and nearly SPAM!)

[Bruce Mendel]

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Mark,

I have a Canadian '93 also with intensive washer system. I am full RS2 kit =
with Stromung. I track the car a lot. I probably put 30 track days on the c=
ar this summer (about 15 2-day events), which is plenty for a 4000lb 160KM+=
 car.

As you can imagine, running 26 lbs on the track, I get major heat soak. I w=
as seeing 2-3 seconds increase per lap towards the end of each run group, a=
nd the car just felt really weak, so I decided to do something about it.

I looked at FMIC, but it was very expensive, requires body and paintwork, e=
tc. Then I started looking into water injection, and it offered all the thi=
ngs I wanted; reasonable cost (although you can spend a lot if you want a h=
igh-end system), tremendous intake temp drops (90+ degrees F drop is common=
), and eliminated the need for me to run 100 octane on the track, saving me=
 a good $75 per weekend, so the system paid for itself. Plus, if you use bl=
ue washer fluid with methanol in it as your injected fluid, you get extra f=
uel as well.

I wound up with an Aquamist system, which is what the WRC rally guys use. I=
t's a really well-built system. There are some others, and Bob Pastore is b=
uilding a home-made unit with a military-spec pump! It kicks butt. On ebay,=
 there are Snow, Holley, and some other systems floating around. Just do a =
search for water injection. Systems run from $150 to $800, but make sure yo=
u get one with a pump good enough (high PSI) to inject into a high-boost si=
tuation, otherwise it's a waste. The cheap washer fluid pumps are no good f=
or high boost.

So, once I decided to go with Aquamist (http://www.aquamist.co.uk), I neede=
d to choose the system. The less expensive systems work on a simple pressur=
e switch....at a pre-set boost level, they activate and spray water (or wha=
tever you're using) into the intake tract. They act like on/off switches. T=
hese are fine for the track when you also use the throttle like an on/off s=
witch, but can sometimes cause bucking on the street as you hit the boost l=
evel, then back off the gas but water is being sprayed at 100%. Also, if th=
e nozzle you choose is big enough to handle full-boost full-throttle, then =
it's probably overkill for part-throttle part-boost. One way around this is=
 to use two smaller nozzles and two pressure switches (Bob's idea). First n=
ozzle comes on at 8 lbs, for example, and the second one kicks in at 15 lbs=
. You're basically creating a two-stage spray so you do not overspray at lo=
w boost and underspray at high boost.

Another way to design the system is with two activation events, so that onl=
y when, for example, a certain boost level is reached AND a certain intake =
temp or throttle position is reached, it'll spray. This avoids the overspra=
y/bucking issue. Also, Charlie's post about Autospeed articles is right on =
target.....they have great info, but I decided against spraying the interco=
oler as it was less effective than going directly into the intake tract.

I went with Aquamist system 2s, but a hybrid version. I use a pretty big sp=
ray nozzle (0.9mm, and no matter what pump or system you create, buy the aq=
uamist nozzles as they really swirl and atomize the water well so it's a fi=
ne mist and not droplets, therefore less chance of bucking or stumbling), b=
ut variable flow. This is done by putting a high-speed valve in line ahead =
of the nozzle, and the valve gets its directions by tapping off a fuel inje=
ctor lead. In essence, it acts like a sixth injector, only it sprays water.

So, at ~8 lbs of boost, the system activates and sends the go signal to the=
 valve. At the same time, the valve cycles on and off according to the duty=
 cycle of the fuel injector, so that if I floor the gas, the nozzle gets wa=
ter from a 100% open valve, just like the injector. If I feather it, it get=
s 50% open just like the fuel injector, so half the amount of possible wate=
r is sprayed. This way, I can use a lower boost threshold for activation, b=
ut still use a big nozzle that can handle 26lbs sustained boost and keep th=
ings cool.

If you buy the Aquamist system, I recommend you get it from Brad @ KC Impor=
ts, Kansas City, MO
816 333 6582
Email: brad at kcsaab.com
Website: www.kcsaab.com
Contact: Brad Schaffner
He's a Saab guy, but THE guru for turbo water injection systems in the USA.=
 Very helpful and smart. If you do go with his system, he should give you 1=
0% off SRP on an Aquamist (he's a distributor for them) and help you design=
 it. MAKE SURE TO GET THE SIGNAL AMP, and mention my experience below. I ha=
d major problems with part throttle bucking, due to the loss of voltage in =
the line by tapping into the fuel injector lead. The signal amp pumps the v=
oltage back up, so all is like OEM again. Bucking eliminated.

I can tell you more about installation, with pics, once you decide if you'r=
e gonna do it.

The long and short of it?? I now have the exact same lap times at the end o=
f each session as I did at the beginning, no difference in power. It doesn'=
t really MAKE power, in my opinion, but rather keeps you from losing power =
in warm weather, lets you run pump gas instead of race gas or home-brewed T=
oluene, and conserves gas, especially if you use methanol/water mix since t=
he ECU is seeing the extra fuel, and also not dumping fuel to cool the cyli=
nders.

I'd say from my lap times I was losing 40-50 HP due to heat soak, and now a=
ll the ponies I paid for are showing up, and staying there till I decide to=
 turn them off. I use nearly one whole tank of primary washer fluid per tra=
ck session, but did not do enough street driving to get a feel for it as I =
put it in near end of season. I keep it off in the winter by disconnecting =
the relay, as it's so cold that the water would make the car buck (a proble=
m you would not have with a big fat intercooler, by the way).

Basically, WI makes the car feel like every day is a cool, damp day where y=
our car feels like it has extra jump, all the time.

Bruce

----- Original Message -----
From: "Mark Strangways" <strangconst at rogers.com>
To: "Bruce Mendel" <brucem105 at comcast.net>
Sent: Tuesday, January 21, 2003 10:35 PM
Subject: Re: [s-cars] Water injection.


> Knock yourself (well, me ) out.
>
> Let me know what U have seen / done. I am building alot of boost and heat
> from the K24 I have now. Need to reduce that before summer. Limp home mode
> sucks, as does the 100 MPH restart to clear the codes :)
>
> regards
>
> Mark
> ----- Original Message -----
> From: "Bruce Mendel" <brucem105 at comcast.net>
> To: "Mark Strangways" <strangconst at rogers.com>
> Cc: <s-car-list at audifans.com>
> Sent: Tuesday, January 21, 2003 10:25 PM
> Subject: Re: [s-cars] Water injection.
>
>
> > I'm doing exactly that now, and can torture you for days off-list with =
my
> > experiences.
> >
> > Let me know if you have insomnia, and I'll cure it with my emails. :)
> >
> > Bruce
> > ----- Original Message -----
> > From: "Mark Strangways" <strangconst at rogers.com>
> > To: "S-CAR at audifans.com" <S-CAR-List at audifans.com>
> > Sent: Tuesday, January 21, 2003 10:11 PM
> > Subject: [s-cars] Water injection.
> >
> >
> > > On my Can 93 S4 I have the "intensive" washer fluid reservoir. My
> initial
> > > thought is, since I don't have any fluid in it for the last several
> years
> > > why could I not use it and some form of nozzle to inject a fluid (may=
be
> > > methyl hydrate / water in the winter) into the intake just before the
> > > intercooler. I would use a temperature controller to modulate the pump
> > based
> > > on temperature at the intake.
> > >
> > > Does this sound feasible? Or a waste of time ?
> > >
> > > regards
> > >
> > > Mark...
> > >
> > > P.S. I am making a portion of ronin available online to those who
> > expressed
> > > interest. The idea is you can download a "trailer" and see if the
> quality
> > is
> > > what you want.
> > >
> > > _______________________________________________
> > > S-CAR-List mailing list
> > > S-CAR-List at audifans.com
> > > http://www.audifans.com/mailman/listinfo/s-car-list
> >
>