Re: Cowl vs. Snout was: Open Element Air Cleaners

From: Jon Steiger (stei0302@cs.fredonia.edu)
Date: Wed Jun 24 1998 - 02:39:10 EDT


At 01:35 PM 6/23/98 -0700, you wrote:
>IMHO there is high and low pressures potentially developed in that area
>depending on the vehicle and the modifications. Pitot tubes and little
>pieces of string can help define what is what on the Dak. I may give it a
>try just to see what gives on my R/T but no promises as to schedule.
>Glacially,
>BKBridges

   Yep, the cowl area is a great location for fresh air. A cowl
induction hood does indeed suck air in there, as opposed to blowing
air out. In fact, the entire engine bay becomes a low pressure area
when you're moving. A cowl induction hood works on the same sort of
principle as drafting... If a semi is going down the road, the air
rushes off the back, and directly behind it is a low pressure system,
which you can use to help pull you along. (In the winter, look at any
van, minivan, etc. The back will always have more road salt on it than
the rest of the vehicle. That's because it gets sucked into this low
pressure area and hits the back of the vehicle.)
   A cowl induction setup basically parks that semi on your hood, except
that there is an opening there, and the air is allowed to go into the
engine bay. (Which helps to pull the air in since it is a relative low
pressure area.)

   I went through this whole thing back when I was trying to decide between
ram-air and cowl induction. (I decided that at the speeds we travel, either
one will work about the same. The faster you go, the better cowl induction
gets, due to the drag of a forward facing scoop.) Anyway, at one point, I
taped yarn all over my hood to observe the air flow. (Old aircraft airfoil
design trick.) I put a couple of pieces in the cowl area, and they did
indeed get sucked down into the cowl vents at the base of the windshield,
rather than blowing up the windshield.

                                               -Jon-

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