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Discussion Starter #1
Quick question. My car didn't have the plastic ducts that clip underneath so I ordered them in.

I'm just not sure which way they go?! Does the duct clip to the underneath (bottom) of the diffuser or to the top?
 

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The top (engine side). The whole idea of a naca duct is it is a low drag (and turbulence) way to duct air into an area.
 

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Let me get my flame proof suit on.

I have been reading about the F1's now illegal "Blown Diffuser" and now know .001% of everything there is to know about them.

Anyway. If you put the naca ducts on upside down, they do exhaust air from the engine compartment to the bottom of the diffuser, as verified with my trusty yarn tufts and my HD Wing Cam (think cheep GoPro) and a quick test drive.

My .001% knowledge says:
I am still getting cooling in the engine compartment due to air flow.
I am getting more, and even better energized, air flowing under my diffuser (faster air flow under a diffuser is better).
I may even be getting the advantage of the naca ducts acting as vortex generators keeping the laminar flow better connected to the steep (for a diffuser) angle of the diffuser.

Mentally, I figure this is worth 4K to 5K pounds of additional down force:D.
In reality, not sure its worth any:shrug:.

Either way its easily reversible and cheep to test.
 

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No flames, I think the yarn test is a good one. I will have to try it and see how well the flows are connected, maybe throw a strain guage on the diffuser (more downward flex is good).
 

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Discussion Starter #5
I was thinking maybe they had come off from rocks/dirt (lots of dirt roads here) so that's why I wasn't sure if they would mount that way or on the top. I might try them upside down for S&Gs.
 
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