opening up the hood vents for more cooling

[racebronco2]

I bought a damaged hood from a friend who totaled his car and was going to throw it away. I am in the process of lowering the recessed part of the hood by about 2 inches, which will allow about 3/4 inch from any object under the hood. Trying to keep it looking stock. With this mod it should allow alot more air to exit under the hood while allowing our cars to run cool during open track events.
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[Cobalt S/C]

Looks good. That should definatly get some extra heat out of the engine bay.

 

[SVTcobraGirl]

you have wayyy more patience than i do lol
We tried fixing a cobra R hood before... its now collecting dust in our shop......

But it looks really good so far! Outta look sweet once in primer

 

[CobraBob]

I agree that enlarging the openings like that should help expell heat. It would be interesting to know the before and after numbers as far as how much heat is expelled. Post pics of the finished product.

 

[racebronco2]

I still need to at a lip at the front and part of sides of the recessed area so it will help to evacuate more air out of the ngine compartment.

 

[Screamin Cobra]

Damn, definately post pics...never thought about the idea of that.

 

[sgt d]

how will you keep the curve of the hood? where you cut out to add excess and pushed the existing material down, doesn't that create a sharp angle or a crimp, if you will? i hope that comes out as a clear question..lol..

looks great! show more pics with progress.

 

[Yellow2003]

Way cool!
Definitely want to see pics when done!

 

[racebronco2]

how will you keep the curve of the hood? where you cut out to add excess and pushed the existing material down, doesn't that create a sharp angle or a crimp, if you will? i hope that comes out as a clear question..lol..

looks great! show more pics with progress.

the curve of the hood stays the same, the lines in the middle of the hood (front to back)is where it is cut and pushed down. The hood stays the same from the front edge to the beginning of the heat extractor.

 

[Cobalt S/C]

From what I can tell he bent it at the black lines shown on the first pic. Also notice that the fiberglass starts at that point, so I'm assuming that is where he cut it to allow the part in the channel to be moved down lower. Then filled the gap with the fiberglass.

It's very clean looking, I can't wait to see the finished product.

 

[racebronco2]

I agree that enlarging the openings like that should help expell heat. It would be interesting to know the before and after numbers as far as how much heat is expelled. Post pics of the finished product.

I will try and keep temps before and afterwards, (i will be open tracking the car this weekend) and plan on bringing duct tape with me and close the opening to the size it was stock, unless there is too much pressure and the tape won't stay on.

 

[sgt d]

plan on bringing duct tape with me and close the opening to the size it was stock, unless there is too much pressure and the tape won't stay on.

i would imagine that there will be too much pressure but combined with the added heat coming out you may be getting busy with the goo gone on your hood..lol.. wait, that did not sound right.

rephrase, you will have adhesive residue to remove from your hood!

 

[sgt d]

the curve of the hood stays the same, the lines in the middle of the hood (front to back)is where it is cut and pushed down. The hood stays the same from the front edge to the beginning of the heat extractor.

someone else stated the black line. that is where i am referring to creating a angle or a crimp. or is the material flexible enough that it makes a smooth transition down to the extractors? you said that you are going to track test it, so will you have it painted by then?

 

[GA Terminator]

yup me 2, looking forward to seeing the finished product.

 

[SVTkel]

On a related topic, at an SVTOA on track event one of the instructors who has some link to the Ford Engineers (can't remember how) stated the following to me after seeing I had my underhood blanket removed and my opening flaps secured back:
- "Do not ever remove the actual hood vent grill under the assumption that it will remove more heat from under the hood". His statement caught me off guard for a second b/c my grill vents are still on the car. So naturally I asked him for more details. He then claimed Ford spent a bunch of time coming up with the hood vents that extracted the most heat possible. Apparently (according to this fellow) they extract more air when open and in place then when entirely removed.

To me I am not entirely sure what he said was correct. I am trying to recall my fluid dynamics classes from University and the only thing I can think of is that the plastic grill like spacers create an eddy current that helps draw air out from under the hood at speed?

Any thoughts from anyone who has heard this before?

 

[dogmush]

SVTkel, it goes like this:

the vents in the heat extractors are actually smoothers. They cause a smooth airflow over the opening. This smooth highspeed flow over the low speed air in under the hood creates a low pressure area right at the extractor. (like an airplane wing, or the spray mechinisim on a Mirical-Gro sprayer) This low pressue area on the outside of the hood, combined with an increase in underhood air pressure from the air coming in the grill serves to suck out the hot air.

If you take out the little plastic vents, the air traveling over the hood encouters a lip and "tumbles" if you will at the extractor opening. this lowers the relitive speed of the air andcauses the low pressure area not to form. If your curious you can simulate this with a big fan and a fogger on your car. Just pop out one of the vents. With racebronco's hood I would imagine he's going to put some form of smoother back in there and have both the low presuure effect and bigger holes.

 

[dogmush]

IN fact, that's what they're doing here:

They're trying to get smooth airflow over the heat extractors. I can only assume that that particular design didn't work out, cause we don't have it.

 

[racebronco2]

I was not planning on adding a grille/smoother but instead was going to add a lip (similar to the lip on other heat extracting hoods)at the leading edge and along the sides as shown in the pictures below. The angle from the top of the radiator to the stock grille opening is about 70 degrees and now it is 45 degrees,this combined with the lip should help to get more slow moving air out.

 

[racebronco2]

someone else stated the black line. that is where i am referring to creating a angle or a crimp. or is the material flexible enough that it makes a smooth transition down to the extractors? you said that you are going to track test it, so will you have it painted by then?

The black line is where i scribed the hood at but from the underside, was careful not to cut thru the hood. I them used duct tape to position the flap so i could fiberglass it in place, even though it was scribed it was still had qiute abit of tension.

 

[MachME]

very nice man.

youll be very happy doing your own work like that.