water into efi system before injectors.

[Swayze]

so, without getting  into details, a normally aspirated high compression
motor could use this to prevent knock by lowering combustion temperatures.
Now could this be knock sensor triggered? would the H2O anti knock rob
more.or less. power than retarding the spark? (rough numbers).
my application would benefit from a good form of antiknock, that is why I am
asking. I don't plan  on turbo route and won't always be able to 93 octane.
would like to kick compression up to 10:1 or so on pump gas(regularly).
byE
Mike
Swayze
mswayze at truswood.com
kswayze at bellsouth.net
----- Original Message -----
From: "Greg Hermann" <bearbvd at cmn.net>
To: <diy_efi at diy-efi.org>
Sent: Tuesday, March 14, 2000 10:11 AM
Subject: Re: water into efi system before injectors.


> >At 08:20 PM 13/3/2000 -0700, you wrote:
> >
> >>No papers I know of, but have done the math/thermo. Comes out to about
75
> >>or 80% of mass flow rate of stoich fuel mix fuel flow in water will get
you
...........
?
>
> !00 GRAMS of fuel flow would equate to 75 or 85 GRAMS of fuel flow--the
> water is denser than the fuel, though.
> >
> >>Same old saw--gotta have the H2O atomized, but not vaporized until the
> >>intake closes, or you lose because water vapor (molecular weight = 18)
> >>displaces a lot of air (avg. molecular weight =29), thus losing you
power.
> >
> >Probably due to heat difference between liquid water and gaseous water
> >at 100deg C transition, ie Latent heat of vaporisation - can swallow
> >large amount of heat...
>
> Precisely. What is going on is the compression stroke begins to act a lot
> more like an isothermal process than an adiabatic one. Consequently, much
> less power goes into the compression stroke. Temperature at TDC (ignition
> event) is MUCH lower--on the order of 235 to 250 degrees F, instead of 900
> degrees or so.
>
> Lower peak temp after burn means less power available on the expansion
> (power) stroke, but this is more than completely balanced by the lower
> negative power on the compression stroke. (About 1.5% net gain.)
>
> Lower peak cycle temp means significantly lower losses to water jackets,
> though, so net gain becomes still greater.
>
> Durability is of course significantly improved with the lower temps.
>
> Lower temps and lower partial air and fuel vapor pressures at TDC help
> avoid detonation, and there is also the detonation resistance added by the
> highly polar chemical nature of the water molecules themselves  and that
> effect on the free radical detonation precursor molecules during the
> combustion process itself.
>
>
> >
> >>Ideal amount of water increases with increasing effective compression
ratio.
>
> Basically this means that with higher compression ratio, there is more
work
> available to provide latent heat with which to evaporate the water.
>
> Lots of folks don't realize that engines running straight methanol fuel
> have _NOT_ evaporated all of the fuel at TDC!! Not enough work available
to
> provide the needed latent heat! The first part of the burn provides heat
to
> finish evaporating the fuel.
> >
> >Has anyone published any actual curves, water flow vs power vs CR vs Fuel
> >or anything even similar ?
>
> Never seen any, Riccardo published as much as I have seen.
>
> Greg
> >
> >Rgds
> >
> >:) mike
> >
>
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