Fiberglass hood mods... crazy?

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Sorry about repeating what everybody said in my first post.. For some reason my computer wasn't showing the there was more than one page to this thread.

One other suggestion to help airflow under the car would be to make side "rails" that keep the air from coming under the sides and clean up the airflow underneath. Like a nascar sorta. And I stick to my previous statement that the "raising hood" will just hurt. But the flaps might help.
So I have two more things to add if you want to continue with this Idea.

1. If you want it to be subtle why not put the hinges on the underside of the hood? If you get the right hinges they should have plenty of travel.

2. Another thing that might help to get them to raise would be little (1/2" tall should be fine) vertical "roof rail" type things turned sideways in front of the flaps to break up the boundary layer and create a low pressure zone on top of the flaps to help them open. Sorry About the description But I have a mental block as to what they would be called :)

Hope this helps!

Benjamin
 
Benjamin,

I have to try this. My personal feelings dictate that I need to have faith in my own convictions, and it's oh-so-easy, just to put two TALL (3 1/2"?) hood pins in the back, with the holes for the "cotter keys(?)" near the top of the pins, so the hood can rise, should there be sufficient pressure underneath to push it up.

If it doesn't work, I haven't done anything that can't be reversed very easily; I'll just put shorter pins in the back, and go to plan "B", whatever that turns out to be. If the hood won't rise enough to let the underhood pressure out, with no weight on it (light, fiberglass hood), then there IS no pressure and I'm wasting my time, anyway, so the proof will be in the pudding...

With this plan, I don't need no steenking hinges, but your idea is a good one about putting the hinges on the bottom side of the hood! Wish I'd thought of that...:profilel:

Thanks for the ideas!!
 
HAHA! No problem.. I was Just saying that I didn't think it would help you go that much faster. Not that I wouldn't be interested in seeing if it worked. Let me know how it works!

Benjamin
 
bjkadron said:
HAHA! No problem.. I was Just saying that I didn't think it would help you go that much faster. Not that I wouldn't be interested in seeing if it worked. Let me know how it works!

Benjamin
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I'll report, even if it slows the thing down (just my luck!!!)

Thanks for all the good ideas, folks!8)
 
if ur willing to cut up the car a little bit u could take into te idea the superbirds and daytonas with stealing the air from under the cowl, but reverse the air flow and cut more of the stock style slots into ur existing cowl. this would also benifit u cuz it would push the air built up around the cowl over the car.
 
I think you are over-thinking it and may not even pass tech if they see the cut hood. I have two thoughts.. first... seal the carb to the hood with a scoop. If you need to engineer a pan to run an air cleaner but it is worth power and ET. Also, what blown said... Instead of cutting anf adding weight and hardware to make this flappy thing... Just use some radiator or heater hose to raise the rear edge of the hood 1". When you're done racing... pull it out and the hood fits normal.
 
moper said:
I think you are over-thinking it and may not even pass tech if they see the cut hood. I have two thoughts.. first... seal the carb to the hood with a scoop. If you need to engineer a pan to run an air cleaner but it is worth power and ET. Also, what blown said... Instead of cutting anf adding weight and hardware to make this flappy thing... Just use some radiator or heater hose to raise the rear edge of the hood 1". When you're done racing... pull it out and the hood fits normal.
Click to expand...

Moper, maybe you didn't read my post #68 (understandable... lol!), but in it I eschewed cutting the hood. I said, "in the final analysis, all things considered (with no apologies to National Public Radio), I think this long hood-pin idea is OVERALL, the best idea. No cutting of hood, fender panels, nor any fabrication necessary (can you tell I'm L-A-Z-Y????)

That will be my plan of action; buy a hood and some long (tall) pins for the back; might even put one dead center of the line between the two back pins, to keep it from trying to "bow" in the middle, when the underhood pressure (if there is any) tries to lift it, at speed."

The drag strips I run at don't have any tech inspection... No kidding.

This is Arkansas, remember???:cheers:

RE: "seal the carb to the hood with a scoop"

My carb is sealed to the discharge pipe on a Vortech supercharger making 10 pounds of boost... I'd hate to lose that...:cwm10:

I'll let you know if I gain anything; I'm not holding my breath....


 
green1 said:
But aren't you still trying to exhaust air into a high pressure area?
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I don't know.

I realize that because of the shape of the windshield, starting at the cowl, and rising to the top of the car's "top," the windshield acts like an air "bulldozer," pushing its way through the air and the resistance to that by the existing air that is being disturbed, is manifested in a high pressure area at the base of the windshield.

BUT, the hood opening is 10-to 11-inches AHEAD of the base of the windshield. How far forward, from the base of the windshield does that high-pressure area exist before it's dissipated???

That is the $64.00 question.

The trailing edge of the raised hood would normally create a low pressure area behind it, acting like a "flap" on an airplane's wing, or a spoiler on any other horizontal surface, like the level area on a trunk lid.

But, if it's "dumping" into a high pressure area, all bets are off... probably won't work.
I know one thing for sure; I'm gonna find out! :cheers:

Might be next spring before I git-r-dun, but when I do (find out) I'll post the results on here, either way.

I'm counting on that high pressure area not extending forward the eleven inches that exist between the bottom of the windshield and the hood opening.

I would think that by that far, it will have dissipated. That's a poor way to put it. I guess it would be more accurate to say, it won't have been created, yet.... (the high-pressure area.)

Maybe not... lol! I'd say it's a 50/50 bet....

We'll see....
 
it doesnt...
the top edge of your windshild/roof area to a small degree my have a plow efffect..but its mostly the grille and your front edge of the hood..
the high pressure air in the cowl is air that is circulating (like laying a large roll of paper towel accross your hood/cowl..despensing paper towels into the cowl ..and or cowl hood opening...
the front fascia..(grille)will dictate more of how the air acts... if you block off the grille and allow the air to run up over the hood you'll have less under hood air..and more available air in the cowl..
the air going over the roof has the co-anda effect...there is a boundry layer there...this creates a suction...if you where looking to remove air from under the hood..you would need it to exit where there is an extreme low pressure.
like the top of the roof with a Naca duct...
or theoretically where the fake ducts are on a charger door..fwiw.

Mel.
 
mopar melissa said:
it doesnt...
the top edge of your windshield/roof area to a small degree, may have a plow efffect..but its mostly the grille and your front edge of the hood..
the high pressure air in the cowl is air that is circulating (like laying a large roll of paper towel across your hood/cowl..despensing paper towels into the cowl ..and or cowl hood opening...
the front fascia..(grille) will dictate more of how the air acts... if you block off the grille and allow the air to run up over the hood you'll have less under hood air..and more available air in the cowl..
the air going over the roof has the Coanda effect...there is a boundry layer there...this creates a suction...if you where looking to remove air from under the hood..you would need it to exit where there is an extreme low pressure.
like the top of the roof with a Naca duct...
or theoretically where the fake ducts are on a charger door..fwiw.

Mel.
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My 2-cents....

I think it will exit anywhere that has lower pressure than what exists under the hood. Why wouldn't it? Like lots of things, air takes the path of least resistance. If the opening available to it, is 11 inches ahead of the windshield base, which, as you have said, is NOT a high-pressure area, and the trailing edge of the raised hood in fact, creates a vacuum at speed, (and, won't it???) why wouldn't the underhood air exit there?

The air entering the underhood area through the radiator-opening, displaces the air already under the hood. Where does it go?

Out the bottom, beside the engine, between the engine and the inner fender panels.

However, (and correct me if I'm wrong,) underneath the speeding car, exists a high-pressure area that occludes, to a degree, the path for that exiting air. The air continues to enter the underhood area through the radiator opening in ever-increasing amounts as the car's speed increases to, say 120 mph. About 60 mph, I would GUESS, the pressure under the hood will raise the back of the lightweight, fiberglass, hood and provide an exit path for the underhood air.

If that won't work, I would really like to know why.

Thanks for any information!!!:read2:
 
I dont want to be or come accross as arguementative.....
i will say ,,,once the world was thought to be flat.
who knows you may be onto something?
go for it..
not really sure what exactly your wanting to accomplish?
you could just put 2 naca ducts in the hood...will do the same.
but i think most of the air exits underneath like you mention'd
what are you doing for intake/carburator air? are you planning to isolate the carb with some sort of carb pan...i think thats what you had planned?
otherwise you will suck air away from the carb..
i am gonna re-read your posts again....
my grandfather told me about Don Carlton..i know he did a lot with airflow on race cars...ive seen stuff on the net about it..
there are pictures out there...
i am gonna stay out though and read..
Mel.
 
mopar melissa said:
not really sure what exactly your wanting to accomplish?

I think that the high pressure under the hood (IF there IS any) needs to be discharged in the interest of allowing the car to move forward with a smaller amount of aerodynamic drag. Allowing that air to exit might produce less drag, I think.

you could just put 2 naca ducts in the hood...will do the same.

Are they visible from the other lane? Stealth is a large part of my plan... a flat hood is a strategic "plus" for me...



what are you doing for intake/carburator air? are you planning to isolate the carb with some sort of carb pan...i think thats what you had planned?
otherwise you will suck air away from the carb...

Check out the picture attached to this post. I will eventually re-do my intake filter location in an area that has cool air, but, not right now...
Thanks for asking!

Mel.
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!!!!!!!!!!!!!!!!

100_3266.jpg


100_3228-2.jpg
 
Wikipedia says (relative to the way an NACA duct works,) "When properly implemented, it allows air to be drawn into an internal duct, often for cooling purposes, with a minimal disturbance to the flow."

So, an NACA duct would be one way to get more air into my underhood area. That is exactly the opposite of what I am trying to accomplish.

I want to REMOVE air from under my hood, not add more.

RE: "these guys thought of an idea and they tried.it...
its the American way."

Well, I thought of an idea, too, (though I didn't originate it) and I'll be trying it... a hood that is allowed to rise a few inches, in the back, due to underhood air pressure (IF THERE IS ANY) and the opening that results from the raised hood will ostensibly, allow the underhood air to escape, enhancing the de facto (aerodynamic) drag coefficient.

If it doesn't work, I'll know I was barking up the wrong tree!!!:cheers:
 
Well yeah you can see them.. you just said that you didn't see how it would work. I still think the long hoodpins in the back are the best bet for anything with the hood.
 
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