NACA Duct Fresh Air Project

[GO DAWG GO]

I have been pondering a way to get more fresh air in to the 911 cabin using the existing dash air system in the 930. first and lastly a way to get air into the trunk area without the dust and sand that a brake duct system mounted low intake will usually generate.

Went on ebay and bought a donor hood (Didnt want to modify my original, It is very pristine) that was luckily guards red. Purchased a pair of NACA ducts and positioned them for optimal airflow and clearance. Anyway, this is what I came up with:

Laid out the simulated card board ducts on the hood as shown, verifying obstructions and duct routing. My strutbar was a concern:




https://en.wikipedia.org/wiki/NACA_duct





carefully cut out the duct profiles in the donor hood.



Added pressure vents, blocked sanded and painted:



Paint and color sanding

Color sanded, then duct installation:




Going to install it tomorrow and see how she looks!

[911tracker85]

interesting. as I pulled the AC, will be watching how you do this and how well it works. looks really 'cool'.

I am also in the process of deciding how to vent the front oil cooler, other than under the car as it was.

I see folks fabricate ducting into the boot and then up and out the hood.

I was considering cutting a vent on the front of the boot right behind the oil cooler, then cover and duct the air to the fender wells. the fender venting on the slant would help pull all that out. with venting as you are doing, would not want all the hot air come right up and into the cabin venting.

and what is the purpose of those pressure vents?

[Craig 930 RS]

With AC pulled, no air comes from my dash vents at all - either defrost or floor. That stinks!

[GO DAWG GO]

Fitted the hood this morning. Now running the ducting and fan. Will add more pictures as the project continues.

I like the look with my factory brake ducts and rockers..

[GO DAWG GO]

[flat6pilot]

Looks great! Where did you source the vent on the hood behind the NACA ducts?

(you need to go to H4's though... )

[GO DAWG GO]

Kyle,

ebay... Hood, ducts and grills. NACA ducts come in any size you desire. My 930 came with H4's. I prefer the sugar scoop look with the updated lenses..

[GO DAWG GO]

Bob Cox,

The pressure vent idea was derived from experience on the track and the propensity for the 911 hood to pop open (unlatch) under extreme body torsion moments. The 911 is known for this and that's why anybody who drives spiritedly should install the strut bar ( see attached)



I have tracked my car and have noticed though hard cornering that the hood can sometimes unlatch.. if you were unaware and then ran down the straight away at 170 MPH like I have. There is a very strong possibility that your hood could very well come unglued. Fold up like foil. When the hood is unlatched there is a boundary induction area of about 1 inch x ~30 inches. ( This wouldn't normally happen with a street car) but in simple terms, consider what would happen with 1 PSI over pressure delta from at that speed and the force on the hood. The area+delta pressure is about ~700 lbs . I don't want to install hood hold down pins in my 930. trying not to molest it that much. The vents in terms of area are much larger than the induction, so in the event this ever happened on the track it would save my car from a severe beating. The induced air would vent out though the pressure vents. Anyway- that's my idea for there installation.

Thanks

Bob

[911tracker85]

hmmm... as my 911 na only hits about 120 and I never had the hood come loose, never thought of this.

how are you ducting your front oil cooler? just under the car?

I really like what you are doing. keep the details coming.

[reachme]

Looks beautiful!!!
Should really bring the air in
hope it doesn't rain

[GO DAWG GO]

Reachme,

I thought about that when I just wash it and how water can get in the ducts and vent. Soooooo, I bought a sheet of that magnetic sheeting and will cover the ducts/vent when i wash it. For the rain: That girl doesn't go out in the rain...LOL. She's a garage queen. I do drive it once a week in the sunshine.

Glad you like it!

I bought some corrugated RV dump hose 3" diameter to plumb the NACA ducts, Because it is corrugated and tends to retract back to a collapsed state. Thus, when I open the trunk it will expand and retract when I close it, keeping the flow of air as straight as possible.

Thanks

Bob

[Craig 930 RS]

Smart!