Functional Bulge Hood Vents - Good or Bad?

[Carlwalski]

My Dad and I measured, marked and drilled holes into my hood scoop plates as well as remove the vent scoop steel deflecting behind the plate too by drilling out the rivets for better flow. At the time, I thought it helped vent out hot air from the engine bay. Talking to a local Kiwi MoPar mate, he seemed to think there'll be zero benefits where as I do. We agreed to disagree hahahaha. My Dad done a great job too and once in place, with the dark shadow of the engine bay, the holes are all but invisible.

I'm not fussed if it does nothing at all but I am curious to hear it there are ANY benefits? I thought cold fresh air came in through the grille and the hood vents helped push air out (like a chimney) and even perhaps a little cool air flowing in. Any input or factual evidence to support either (if it works or not) would be much appreciated. I love my scoops and have always thought vented SURELY have to be better than a block off plate.

[aris_unlimited]

If nothing else it should provide cooler engine compartment temperatures.

[hooD]

http://www.cuda-challenger.com/cc/index.php?topic=46652.0

[Carlwalski]

http://www.cuda-challenger.com/cc/index.php?topic=46652.0

Thanks bud, I JUST found that too lol. Seems the census is, YES they work, but the only benefit is at slow to zero moving speed and for venting hot air out. For me, the answer is simply: It doesn't hurt anything doing this mod. Plus, I know for most people, stuck at busy traffic lights in the city on a hot summers day is when heat temps start to climb so if these help that, it's a win in my book.


Any other opinions are welcome. 

[Chryco Psycho]

I simply removed the plates entirely & have never put them back in 33 years , I did leave the rain trough in behind on though

[Cuda416]

Other than looking cool, I believe you would see little, to no "ram air" affect other than at low speed. As you move faster, a "boundary layer" forms and will cause the air to move right over the top and no "into" the openings. In fact at speed, it could cause the reverse effect. It's why the T/A scoop is raised and the AAR opening is toward the front (low pressure area I think). Maybe you could get crafty and fabricate some "rear facing escape vents"? I remember years ago reading about "Sledgehammer" which was Lingenfelter's (sp?) 256Mph vette. The side scoops were supposed to be functional but we too close to the body. Car was starved for air until ol' John came out and duct taped some card board extensions on to them to get them out of the boundary layer and finally ran 256, instead of the 220 something he was limited to. If you look at the Shelby GT-KR hoods they have exits toward the back which allows hot air to be "pulled" out of the bay by the low pressure area at the base of the wind shield, which then allows more fresh air to be drawn in, same as the vents at the rear of an AAR hood. I think that's how they work anyway.

Now I am not suggesting your car is going to go anywhere near 200+ Mph but the point is, the Challenger and Cuda hood scoops are purely cosmetic and will not function as a ram set up.

Still, it'd be neat to see a "fresh air" setup like the superbee and roadrunner setups.

By all means, carry on!   

-C

[Carlwalski]

Thanks guys, as I thought, maybe not as a ram air but for venting, never thought they did much for cool air in, but did/do vent hot air out from the bay. I wouldn't really look into a ram air style setup, those things aren't light haha, the little hp you/d make would probably be lost by weight.

[dodj]

Your car will cool more efficiently with the block off plates. With the block off plates there is somewhat of a low pressure area behind the rad. The engine fan then has an easier time pulling air thru the radiator. If the air from the scoops is ducted to the carb then cooling is unaffected.

[Carlwalski]

Thanks Scott, I wonder if you're right, seems like great arguments from both parties. If my car runs hot, I'll know where to start looking to try and help it. If not, I'll leave it as is and hey, it might even run cooler. Only a few screws to replace them and they're pretty small drill holes so it's not like I have great big holes in the hood hahaha. Thanks for everyones input and opinions. 

[cudabob496]

vented engine bay makes radiator more efficient, and reduces car drag,
as front of car is not so much of an air brake.

Old racers raised the back of their hood an inch or two, and gained .3 secs in quarter.


ramairbox.com

every 10 degree drop in carb inlet temp gives a 1.5% power increase.
50 degree drop, 7.5%. On my car, thats 40hp.
Outside engine bay may be 90, but inside, downstream of rad, may be over 200 degrees! Especially if your headers aren't coated.

[dodj]

Old racers raised the back of their hood an inch or two,

  Raising the rear of the hood helps evacuate air. Non ducted scoops do the opposite.

[Sonnythebull]

I took the vents right out of the hood on my 1973 challenger and man it makes a huge difference in cooling. Before the car overheated in traffic badly and ran hot always. Today I drove around in 90 degree weather and in traffic and the car ran perfect with AC on and wouldn't get above 205 but cooled down right away to 190 to 200. Ran cooler in town than on highway even!

[hemiken]

Hi Carl , I was wondering if you can put the myth to a halt at all buddy, i personally think it would work. I was wondering if you could hook up a light under your hood with a mini video camera and do a real life seat of your pants test and post up any result ? PLEASE