water injection questions???

[David Doddek]

Here is my 1/2 cent worth.

Water injection does more than just help to retard detonation.  Someone
worried about it taking away heat from the combustion and wasting power, but
remember when water turns to steam it also expands, A LOT.  This makes for
higher combustion pressures, the steam also cleans out the carbon from the
cylinders which helps to further reduce the chance of detonation.  And
besides the increase in combustion pressure comes in the form of average
pressure and not peak pressure.  Higher average pressure is not as hard on
the engine  and results in greater HP increases.  And water injection does
work.  I had a friend with a Mustang SVO that was a factory turbo test car
from Warner Ishi.  If he pulled the waste gate hose off it would run at 25
psi of boost.  It would also start do detonate at 3000 rpm to the point that
it would cause the car to jerk voilently.  With injecting a small amount of
water, he could run full boost all the way up to red line and toast the 8
cylinder guys.  He just used the boost pressure to pressurize a tank of
water and dump it through a small adjustable valve into the turbo inlet.
Trial and error found the right amount of water.  He did not even use a
nossle. Just dumped it into a vacuume hose port before the turbo.  The
spinning turbo atomized it.

On another theme, adding extra fuel will not reduce knock by a significant
level.  I have a fuel computer that I have made that has the main fuel
adjustable.  I have a 69 ford 302 with 9:1 and without good fuel it will
knock like a pig.  I have accelerated with a good power mixture and
experienced knock.  While accelerating I have turned the fuel up to the
point that the engine was loosing power and rolling black smoke.  Guess
what, the knock was still there.  However making the mixture even a little
leaner would result in knock increasing rapidly until it sounded like a
machine gun.  So the moral is more fuel will only get rid of a tiny amount
of knock at the best, but fouls plugs, washes cylinders, looses power and
gets lousy fuel econemy.  All of this is from experience and not an
uneducated opinion.

To address the worries about running out of water, use a sensor in the water
tank to determine empty.  Wse this to activate a solenoid valve that will
either lower boost via a second setting of a wastegate or cause the diaphram
of the distributor to be retarded or an input to the ECM that changes the
timing curve of your custom EFI box.

And besides, if water was that corrosive to the engine, why does the engine
not fall apart when people live in highly humid climates like fog and rain.
My car always runs better on a cold foggy day.

Well, that was almost a full penny so I better quit.

David J. Doddek                                          |pantera at pobox.com
Owner SGD Electronics & Development Engr for Caterpillar |h 309 685-7965
Formula SAE Team Sidewinder 94-95                        |w 309 578-2931
89 T-bird SC,  69 Fairlane w/SGD EFI                     |fx 217 428-4686
74 Pantera w/Electromotive Tec-II Twin turbos and Nitros |
Hey, If you are going to go fast, go REEEAAL FAST.       |