IIRC, it's because the water flashes to steam. Therefore, properly
timed water injection augments the gases produced by gasoline
combustion, to produce a larger volume of "stuff" to push the piston
more strongly on the power stroke.
IIRC.
-Simon

On Tuesday, December 10, 2002, at 08:56  AM, John Rodgers wrote:

> For what it's worth department:
>
> Water added to fuel under the right conditions and in the right way is
> a
> plus.
>
> During WWII the Corsair aircraft engines had a water injection system.
> When the situation warranted, the pilot could achieve "military Power",
>  slightly above rated power, by going to full wide open throttle. This
> would activate the water injection system. Apparently the addition of
> the water enhanced combustion to develop the extra power for
> emergencies. Possibly by reducing heat, or changing the burn pattern to
> enable greater power, ot maybe something else from a theory standpoint.
> I don't know. I just know that it was done, and it worked.