Water injection

[Igor Kessel <four_rings@worldnet.att.net>]

Dave Hedgehog wrote:
> 
> Yes, that was my understanding of water injection, it reduces combustion
> temperature (as does nitrious) so allows more fuel and air to be burnt
> (increases air density), prevents cylinder head and valve thermal damage and
> prevents detonation.

and Pantelis Giamarellos wrote:
> 
> Apart from all the things you said, W/I companies also auote cleaning carbon
> deposits as an additional advantage.

OK, I resisted this thread long enough but it's time for me to chime in
as it seems like I am the only one on the List with the real life BTDT
on the subject. Both Dave and Pantelis are absolutely correct. BTDT.

Back in mid-80s the supply of 93 octane was intermittent in some regions
of the Soviet Union. Since I love(d) to travel and at the time owned
high compression Ladas I started looking for alternatives. I took advice
of a friend engineer working for one of the Government jet fighter
manufacturers (I think water injection was used in aviation) and
designed and installed the water injection sys on my car.

Water, injected through a 0.35 mm needle jet through one of the
carburettor hoses did indeed allow me to use the 76 octane without any
detonation (pinging). It also increased the power output of the car
_dramatically_. Oh, one more thing: the fuel consumption went down as
well. Kinda win-win-win situation, sounds too good to be true. I
wouldn't believe it myself if did not experience this on my very own
car. There's a catch however: I went through the lousy non-SS Lada
exhausts like through brake pads. The perpetual condensation/evaporation
cycles and hot water vapour turned the exhaust into a regular
consumable. 

It was utterly funny when I would be driving along with some friends
when suddenly the engine would break into detonation. I would casually
remark:
-"$hit, ran out of water!"
My passengers, jokingly:
-"What, you car runs on water?"
-"Yep"
I would pop the hood, refill the auxiliary 5L water reservoir (used for
the headlight wiper misters) and continue on driving. The pinging is
completely gone. My passengers look totally astounded.

I finally ditched this system coz in Russia the winter is rather cold
and the sys would freeze up. I toyed with the thin Cu tubing wound
around the downpipe but it did not take care of the water freezing in
the jet. I took the engine apart, removed the pistons and turned them
1.8 mm on the lathe reducing the compression enough to use the low
octane gasoline. Lost the power as well but it was better to drive
slower than not to drive at all because the 93 octaine was so scarce.

A friend of mine drove his water injected car all year round coz he
would dissolve a tablet of dry alcohol in the water reservoir,
effectively lowering the water crystallisation point. These tablets were
sold in Russia in the sporting goods stores, catering to tourists and
alpinists who used them as a flame source for cooking meals out in the
field.

One thing that shocked me when I took the engine apart was a complete
lack of any carbonisation. This is no exaggeration, the pistons and the
combustion chambers were covered with just a thin film of flat grey
oxidised Aluminium. Not a spec of Carbon! That was a first time that I
took an engine apart and it had no deposits whatsoever!

I have never attempted to install a water injection system on a
turbocharged car so please don't regard this post as a wholesale
endorsement.

-- 
Igor Kessel
Two turbo quattros.