New Hood Mod! NACA Ducts!

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11/25/2006, 11:31 PM
SilverBullet75

New Hood Mod! NACA Ducts!

Hi!
I've been waiting a long time to get up the kahones to do this. I've always loved the way these look on High-End sports cars/rally cars/etc... So, I took 2 days off of work and just DID it! I installed NACA ducts in the hood... and yes, they are functional! (what do they do? well, um... they let air into the engine bay right now... AND LOOK COOL DOING IT!! :) ) Eventually I'll get them ducted toward the air cleaner, but for right now they just totally give the agressive look I've been wanting for my VX. I've attached some pics of the process and the end product. Let me know what ya'll think!
---JIM---
http://www.vehicross.info/gallery/da...A_Ducts_01.JPG http://www.vehicross.info/gallery/da...A_Ducts_11.JPG http://www.vehicross.info/gallery/da...A_Ducts_19.JPG http://www.vehicross.info/gallery/da...A_Ducts_21.JPG http://www.vehicross.info/gallery/da...A_Ducts_46.JPG http://www.vehicross.info/gallery/da...A_Ducts_30.JPG http://www.vehicross.info/gallery/da...A_Ducts_45.JPG http://www.vehicross.info/gallery/da...A_Ducts_43.JPG http://www.vehicross.info/gallery/da...A_Ducts_40.JPG
11/26/2006, 12:07 AM
Ldub

Very Nice...I mean wayyy nice... :cool:
I've been wanting to do the same for some time...only I was thinking of putting one directly over the airbox to dump fresh air in,& the other in a corresponding loca. on the other side of the hood, maybe even another center forward loca.
I've liked the look of NACA ducts since the first time I saw them on a 69 GT 500.
Good to see what they'll look like, that really kicks!
An e-bay find ?
11/26/2006, 03:00 AM
Hotsauce

Now make a collector for them and feed it to the airbox.

Gotta have some oomfh to back up the look.

John C.
11/26/2006, 05:48 AM
Ruflyf

That is impressive, nice skills and appearance. I have thought of the same thing sort of, except I pictured them extruding upward rather than being inset. I think I like the inset better.
11/26/2006, 05:53 AM
Joe_Black

Looks good! If they're to be functional, please post the amount of pressure you get at various speeds if you get a chance.
11/26/2006, 09:02 AM
biju

woooow!

So so clean. I love this mod, functional or not. It appears they align really well with the fangs, making them fit in really nice.

Thanks for posting!

-biju.
11/26/2006, 09:06 AM
SilverBullet75

Thanks!

Thanks all!
Yes, eventually they will be plumbed into the airbox, but right now I'm out of budget $ and time.

As for the ebay question... no, these are 100% hand made. I started it by designing the shape on Adobe Illustrator. Then measured the insert for placement. Then, cut out the insert, cut the sheet metal hood below the insert, and used the cutout pieces as the "trays" for the ducts. From there, fiberglass and body filler went into play...
16 hours later...
They are done!
Only one thing I'm going to fix... I added a mesh screen. I don't like it though. It's used to cover up the bare sheet metal and hood structural supports. So, I'm going to cut the hood about 5 inches more toward the interior so that none of that will be seen, and I wont need a screen.

Oh... an for the request for pressures... Dude, I'm a jack-of-all-trades, but not a windtunnel expert! LOL :) I wish I could help with that info. It would be useful I'm sure.
Thanks!
---JIM---
11/26/2006, 09:13 AM
Ldub

Just a thought re: mesh/ cutting more sheet metal/ hiding bare metal...

Flat Black Paint, Covers A Multitude of Sins. ;)
11/26/2006, 09:16 AM
SilverBullet75

LOL... believe me.. I've tried!
11/26/2006, 09:45 AM
Triathlete

Hmmmm! Whats going to keep the water out on those rainy days?
11/26/2006, 09:51 AM
VCAMILO

Awesome! The mod looks real nice... It never rains in AZ or in Nevada... LOL!
11/26/2006, 10:48 AM
Ldub

Quote:

Originally Posted by Triathlete

Hmmmm! Whats going to keep the water out on those rainy days?

I was thinking a chunk of sponge or high density foam cut to fit (HAS to be black, of course), would slow it down to a drip on those rainy days & keep out most of the cold air during the frigid winters we experience way up nort.
11/26/2006, 10:54 AM
thedutchguy

Me think you brave man to take two days of !
11/26/2006, 01:29 PM
iamjacksadrenalgland

actually, NACA ducts are designed to vent air out from under the hood. there's a pressure difference between air flowing over the hood and air trapped under the hood.

this issue was debated at great length on a porsche forum that i used to belong to when 944 owners considered using hoods set up with NACA ducts plumbed to their intakes.

... and now for today's automotive fun facts ...

in 1979 porsche decided to build a turbocharged version of their normally aspirated 924. in order to accomodate the extra heat generated, they fashioned an NACA duct directly over the exhaust manifold/turbocharger.

in 1981 porsche offered a limited production 924 carrera GT which utilized an intercooler between the turbocharger outlet and the intake manifold. the resulting temperature drop allowed for more boost and more power. in order to provide airflow over the top mounted intercooler, they fashioned a large scoop on the hood.
11/26/2006, 01:50 PM
Hotsauce

Quote:

Originally Posted by Ldub

I was thinking a chunk of sponge or high density foam cut to fit (HAS to be black, of course), would slow it down to a drip on those rainy days & keep out most of the cold air during the frigid winters we experience way up nort.

Cold air= power. Cold fresh air is good, but obviously too much water is bad. My truck makes noticably more power on really cold days.

I really don't think you can get up enough air pressure for any signifigant ram air effect, but the cold air will help.

John C.
11/26/2006, 02:13 PM
Ldub

Quote:

Originally Posted by Hotsauce

Cold air= power. Cold fresh air is good, but obviously too much water is bad. My truck makes noticably more power on really cold days.

I really don't think you can get up enough air pressure for any signifigant ram air effect, but the cold air will help.

John C.

I'm right there with ya John...to a point, that point being around zero, or a little above.
There's a reason older cars had heat risers ducting warm air from around the exhaust manifold up to the intake, same reason our throttle body is plumbed into the cooling system.
In severe cold, warming the intake (combustion) air a bit makes combustion happen more easily.
On mine, I've plumbed a bypass around the throttle body (using ball valves) that shuts off the coolant during the above freezing months.
My two cents. :)
SilverBullet, Sorry for the thread-jack. :(
11/26/2006, 06:34 PM
Chopper

I think, maybe, save the costs of ducting... let them be extractors. The location is too far back from the airstream to realize any ram effect and is actually in a low (negative) pressure zone. Notice rams are located at the vehicles leading edge (hood lip or grill in GM cars) a high pressure zone, or near the windscreen base (another high pressure area) Cobras, Subaru, and several GM designs. Think about the huge hole, right in that spot, on an Evo... it's all about getting heat out. They even designed in a little" kick"around the hole to lift the air even more, creating more "suck" I think the piping won't help anything,and if made tight,may hurt. IMO love,Wayne
11/26/2006, 07:04 PM
SilverBullet75

My inspiration...

My inspiration for the ducts actually came from the Porsche
924 Turbo
968 Turbo S
928 GT - Custom

Even if they don't work quite the way they are supposed to, I'm happy that they look cool and provide even a LITTLE bit of extra cooling during the Nevada summer
11/26/2006, 08:06 PM
VCrossfan

Looks nice Bullet...Hats Off ! ! !
11/27/2006, 07:47 AM
WormGod

Looks good and clean. Killer work!

I would love to do a sort of Evo style insert mod to suck some heat out. Unfortunately, that would mean losing some stability in the hood from the cutting needed, but damn, would that look good.
11/27/2006, 08:02 AM
SilverBullet75

Thanks!

Question...
For those who have the CF Hood Scoop... Is there any other function built in than just cooling? The scoop is placed even further back than my NACAs!
Just curious.
Thanks!
---JIM---
11/27/2006, 10:30 AM
Ruflyf

Quote:

Originally Posted by Chopper

The location is too far back from the airstream to realize any ram effect

He could always just supercharge that would make the air flow more of a direct feed to the intake, or better yet let me test the hood out on mine. :)
11/27/2006, 11:09 AM
WormGod

The scoop offers little airflow, so even cooling is minimal. The slope of the hood appears to raise airflow over the scoop more than in. Sometime back I taped some ribbons around the hood and near the scoop. All airflow is more to the front of the hood, so the scoop would need to be positioned more at the very front of the insert. There is SOME airflow at the scoop location, but I dont think it would be enough to utilize as a proper ram air. I went through this way back when, when I decided to try a ram air mod, but it simply wasnt enough to work with. We suffer the same issues that the STi hoods suffered pre- '06. The scoops were enlarged for more air to be scooped in to the TMIC. I am thinking that a pre- '06 STi hood scoop size on the VX would look insanely silly.

Our best bet for good ram air is through the grill or better yet, mod through the round parking lights in the front cladding.
11/27/2006, 11:30 AM
Triathlete

This might work...

http://static.summitracing.com/globa...c-101090_w.jpg

Its even Proton!!!! :bwgy: ;eeky; :laughy:
11/27/2006, 01:54 PM
AlaskaVX

Quote:

Originally Posted by SilverBullet75

Thanks!

Question...
For those who have the CF Hood Scoop... Is there any other function built in than just cooling? The scoop is placed even further back than my NACAs!
Just curious.
Thanks!
---JIM---

Mine is only used for cooling and it works better then I would have imagined. It blows cool air directly on my supercharger and after a 300 mile trip with hard driving I can put my hand on the top of supercharger and it is almost cool to the touch.... it used to be quite warm after the same trip.
11/28/2006, 08:01 AM
WormGod

Quote:

Originally Posted by Triathlete

This might work...

http://static.summitracing.com/globa...c-101090_w.jpg

Its even Proton!!!! :bwgy: ;eeky; :laughy:

You might want to pop your hood once a day to make sure the mailman didnt stick any mail in there. Might start a fire under the hood. ;)