Presented by Nine Lives Racing
iansane
iansane GRM+ Memberand Dork
9/15/23 2:12 p.m.

So I'm buttoning up a swap on an '85 celica that required moving the airbox and I'd like to make sure I will be feeding it enough air. Initially I was just going to hole saw and pull air from behind the popup headlight but I had an idea. The car has a pretty sizable fiberglass front lip spoiler on it and I could fairly easily sink a NACA duct into where that front spoiler wraps around the fender. Essentially it would be at the base of the fender in front of the wheel. Is this a terrible place to pull air from? Mediocre? Wonderful?

It would actually be on the driver side but getting a picture was easier on the passenger side because of how close the lift is to the wall.

 

The front end looks like this;

You will injest more dirt down there.   YMMV

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
9/15/23 5:54 p.m.

From my understanding, a submerged duct like that works best with nice laminar airflow. Around the squared off side of that air dam, I'd expect low pressure and possibly separation. You'd probably do better pulling from one of those foglight holes.

Appleseed
Appleseed MegaDork
9/15/23 6:08 p.m.

NA A ducts are hard to get right. The edges need to be virtually sharp enough to cut you.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
9/15/23 7:03 p.m.

In reply to Appleseed :

Yes, those sharp edges drive the vortices that make it really work. But they also make it relatively easy to fabricate out of sheet metal, especially since all the diagrams you need are published.

That said, even the sloppy plastic ones still work surprisingly well. I had some on some side windows and they pumped a significant amount of air.

VolvoHeretic
VolvoHeretic GRM+ Memberand Dork
9/16/23 5:57 p.m.

Nice permanent notepad on your forearm. laugh

iansane
iansane GRM+ Memberand Dork
9/18/23 11:40 a.m.
Keith Tanner said:

From my understanding, a submerged duct like that works best with nice laminar airflow. Around the squared off side of that air dam, I'd expect low pressure and possibly separation. You'd probably do better pulling from one of those foglight holes.

Oh definitely. If I could convince him to ditch the fog lights then that would be the solution. I guess I was just wondering if down low here would be worse than just pulling haphazardly from behind the headlights. I don't think I could duct from the grille area.

iansane
iansane GRM+ Memberand Dork
9/18/23 11:41 a.m.
VolvoHeretic said:

Nice permanent notepad on your forearm. laugh

Ha, thanks. Horrible short term memory and years in a parts house running down parts.

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