<VV> anyone have a diagram for homemade vapor injection?

[FrankCB at aol.com]

But the most important distinction between the 2 is  NOT whether the water 
enters the engine as a liquid, as droplets, as a coarse  mist or as a fine mist. 
 The most important difference is HOW the  water flow is varied.  So-called 
VAPOR injection occurs when a small part  of the intake air is diverted through 
the pool of liquid water where it sucks in  water vapor with it.  Since this 
air flow is dependent on intake manifold  vacuum, it is highest at idle and 
deceleration and lowest at full throttle which  is just opposite to where it is 
most needed.  WATER injection, on the other  hand, depends on a pump (or 
pressurized air tank) to move the liquid water into  the intake air/fuel mix.  Thus 
it is normally shut off at idle,  deceleration and low load situations.  The 
control is usually set up to  INCREASE the water flow as the engine load and 
rpm increase.  Boosted  engines sometimes use boost pressure to PUSH the water 
which  automatically increases the flow as boost pressure increases.  
    Earlier and cheaper water injection systems used a  simple windshield 
washer pump to dribble water droplets into the carbs, some  actually increased 
the water flow by increasing the voltage to the pump as rpm  increased.  They 
used a vacuum switch to only turn on the pump once the  intake manifold vacuum 
became lower due to increased load on  the engine.
    Many years ago I built my own system using a  surplus high pressure 12 
volt water pump that blasted a fine mist of water  into the top of each carb 
(110 engine) through 2 "surplus" kitchen plastic  sprayer nozzles.  If I 
remembered to push the button under the  dash as I began to accelerate, the engine was 
quiet and smooth.   If I forgot, the sound of a bunch of rattling empty Coke 
bottles (remember  them?) behind me was my "reward".  The system certainly 
worked, but  left a lot to be desired in terms of actuation.<GGGG>  But it did  
prove the concept was valid.
    Modern systems use computerized controls to  automatically turn on the 
pumping and vary the flow based on rpm as well as  engine load.  MegaSquirt even 
has an option whereby you can set up a  SEPARATE water flow "map" (similar to 
the fuel flow "map")  that uses  the same sensors that vary the fuel flow to 
turn on and vary the  WATER flow but at a different rate.  But the "maps" are  
completely independent so you can keep the water shut off until you need it  
and vary the flow based on rpm and load.  Aquamist undoubtedly does  something 
similar with their computerized control on their water  injection.
    I personally prefer the fine mist type with  injection to occur 
DOWNSTREAM of the turbo since I've also heard reports of  water erosion of the turbo 
compressor blades.
    Frank "finally ran out of words" Burkhard
      
 
In a message dated 1/7/2008 8:33:41 PM Eastern Standard Time,  
deltainc at grm.net writes:

-----  Original Message ----- 
From: "Jim Burkhard"  <burkhard at rochester.rr.com>
Subject: Re: <VV> anyone have a  diagram for homemade vapor injection?

***********
I suppose we  should avoid calling water MIST injection ....  " vapor "
injection  ... misting is still just small liquid water droplets ....    this
is the normal, good kind of water injection ... water wont go into  the
"vapor " or GAS state until it boils ...

... a cold stream  sprayed into a turbo compressor intake will probably be "
misted" pretty  good, but there are some reports of damaging the turbo blades
thataway  ...

So use a NOZZLE after the compressor stage to create a MIST by  using a fair
amount of pump pressure.

***********
on my v8vair, I  made a " lumpy-misting " special threaded air filter hollow
crossdrilled  air cleaner hold down rod; after tightening on the big z28
filter housing,  I just stuck the water feeder tube from the pump onto the
top of the  threaded stud.  that seemed to work just fine, the coarse  mist
probably got mixed pretty good on the roaster at the bottom of the  plenum.

*********
a fine distinction, probably without much  difference, possibly not much
merit.
ken campbell, myway in  iway







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