[Diy_efi] WI, methanol, and corrosion

[Greg Hermann]

At 4:19 PM 1/23/03, Axel Rietschin wrote:
>----- Original Message -----
From: "Greg Hermann" <bearbvd at mindspring.com>
>
>> maybe even a net gain !!
>
>This is the part where I fail to follow the reasonning. You add something to
>the intake charge, that something takes space, I pretend that the space
>taken displace some of the original charge so there is a net loss or at best
>a no-no. I fail to see how the engine can swallow more air if the air in
>question is diluted by water vapor. Note that I don't question the
>usefulness if WI, it's just that I fail to see how you can gain anything by
>letting the water evaporate before it reaches the cylinder.
>
>--Axel

The water vapor occupies space in proportion to its partial pressure in the
mixture of gas.

If the partial (and saturated) pressure of the water vapor is less than the
pressure drop of the (water free) air going through the IC, then the
partial pressure of the air mixed with the water vapor will be HIGHER than
the pressure of the air after it went through an IC. Hence, more air to
burn.

Examples:

With an IC:
Pre IC manifold pressure= 37 psia (22 psig boost)
Post IC boost pressure = 35 psia

Manifold partial pressures, post turbo, no IC, but WI:
Air = 36 psia
Water vapor = 1 psia
Total manifold pressure = 37 psia

Note that the compressor is doing the same amount of work in either case,
hence should be about the same back pressure from the turbine on the motor.
Guess which one of these two cases has the motor ingesting more mass flow
of air ??

Greg



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