Under most conditions the opposite will be true.  Air with a lot of water vapor in it is a bit
more dense, increasing its ability to transfer heat.  This effect will be minimal on engine
cooling, however, with temp being the important consideration.  Temp is important both because
obviously hotter air won't cool as much and because hotter air is less dense, and less dense
air also won't cool as much.  On the other hand, more water vapor (or actual water) will have a
BIG effect on performance, as Stan has pointed out.  Remember the old 50s song "Mabelline"?
"Rain was a pourin' up under my hood... I knew that was doin' my motor good."  Now, let's all
sing together.  "Mabeline, why can't cha be true?"

Bill

----- Original Message -----
From: "Vanagon man" <vgonman@msn.com>

>
> I thought that when water is added to air, it changes its properties, and
> thus cooling capacities.what i thought (from some long ago fluid dynamics
> class) is that when water is in air and it is forced thru our air cooled
> engines, it will not collect and move the heat from our engines as well as
> dry air...................