Water injection.

[Bernd Felsche]

Mike writes:
>At 02:19 PM 18/3/2000 +0800, Bernd Felsche <bernie at perth.dialix.com.au> wrote:

>>So at this time, I'm "stuck" trying to find the right technology.

>Hey Bernd,

>How about the $10 pumps from Dick Smith - I'm using one at moment to
>pressurise my cooling system and purge air bubbles from the head (and yes
>there are two bleeds for this purpose - I've connected to a solenoid),
>it easily reaches 15psi and if hold off the water overflow line,
>reaches about 18psi at 11.8v

My main concern with pumping water directly is with it running dry.
That's why I like the idea of using an air jet - provides excellent
atomisation at fairly low pressure - but you need the flow (or vice
versa). What convinced me was watching a spray-painter: They don't
pressurise the paint cans.

Then there's the stuff that's in the water - loads of minerals. The
8 litres of water I put in my windshield washer reservoir is enough
to discolour the inline filter I put in. (The filter is virtually
useless - it didn't cost much to try - but I wouldn't recommend it.)

Perth water: You can make a meal of it!

>These are centrifugal and will do 15psi easily - though they are very
>temperamental if there's the slightest amount of air in the line.

They tend to be.

>The impeller is also a little temperamental if there's any dirt, it causes
>the impeller to shaft to strip - but reglung it is easy.

What is easy?

>With a good filter, correct positioning etc, it should be possible to
>operate them reliably - thats what I will be trying shortly,

It'll be interesting to see how well (and long) it works.  Make sure
your water tank has anti-surge baffles and put in a level sensor
that triggers well above the suction line. Not sure how you'll go
with sucking water through an inline filter - I suppose if you
ensure a static head it should be OK.

>Could run two in series with appropiate bleed-leak from the second back
>to tank (because the seal at center will be at the outlet pressure of
>the first one - but would generate 30psi overall without much trouble :)

>You can get them from the Dick SMith store in Osborne Park (Aluminium valley).

Pretty sure I can get one through the store down in Rockingham.

>>Two other benefits for road cars; on hot days, the evaporation cools
>>the charge. On cold days, you can pre-heat the water and use the
>>warm mist to help pre-heat the charge air for better fuel
>>vapourization.

>:) Not much chance of the latter over here even in winter, with 10psi
>boost temps are over 100deg C at comp outlet :( but then for n/a I'd
>probably go with a fuel rail heater if you were worried about vapourisation.

Well I do find that there is some preheating necessary for the fuel.
After removing the intake silencer on my (and getting a very nice
transient throttle response improvement as well as a drop in fuel
consumption), I found that the engine would sometimes falter on
sudden throttle openings during cold nights and mornings; when it's
5C or less.

The reason for that was that the pre-heat flapper used to close
against the outlet of the intake silencer - which was no longer
present. So the engine got a healthy dose of very cold air.

The pre-heat flapper is thermostatically-controlled, with vacuum
servo to move the pre-heat as required. The flap is supposed to be
fully closed at 25C, Fully open below 20C. That's also to prevent
icing of the throttle valve, btw.

My fix was to put in a new flap across the opening left by the
removal of the silencer, and link it back to the pre-heat flap so
that it would shut off cold air when preheat was required.
For the price of one wire coathanger and the base of an icecream
tub, I fixed the problem. It's worked for several years now.

The fuel rail is btw close to the head on my car - it holds in the
injectors, so it gets quite warm.

BTW: My Atmel-based ECU page has been updated
	http://perth.dialix.com.au/~bernie/tech/EFI/vapour/Resources.html
added Timer/Counter and Interrupt resources and expanded the Pin
Allocation.

-- 
Real Name: Bernd Felsche
Email: nospam.bernie at perth.DIALix.com.au
 http://www.perth.dialix.com.au/~bernie - Private HP
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