Miata Mailing List: September 1993, Message #91
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   From: Mike Rother 
Subject: Air Intake
   Date: Mon, 13 Sep 1993 11:40:27 -0400


Here's another opinion regarding the "water in the intake" discussion.

We should be concerned about drawing in water with intake air.
However, there are different levels of "water."  The stock Miata airbox
draws air below the filter - pulling it upward - and has two water
drain holes in it's bottom.  After that it's a long way to the intake
runners - through warm ductwork.  Correct me if I'm wrong, but drawing
in some drops of water is not going to hurt your engine.  It probably
happens with the stock intake.  Those drops probably stay in the bottom
of the air box or evaporate on the way to the combustion chambers.  In
fact, an age-old method for blowing out carbon involves slowly pouring
a GLASS of water into the combustion chambers as the engine is
running!  Although I wouldn't advocate it, some water in the intake
mixture can actually improve performance.  I recall reading about
"water injection" systems as performance upgrades.

What I would be concerned about is a significant inflow of rain drops,
or quantities of water from fording those 1 foot deep puddles
meantioned in an earlier posting.  I would be concerned about wetting
down the air filter and/or getting too much uncompressible moisture
into the combustion chambers.

If you tinker with your intake and wonder about water coming in, here's
a tip.  Drive in a hard rain with headlights up and down.  Spend some
time behind another car that is sending up a spray.  Drive through some
puddles.  Then pull in under the canopy of a closed drive-through bank,
open the hood, and check where the water is going.