Legit cowl hood?

[98chevy2500SS]

You got any pictures of his truck? Sounds pretty nice! You know there is a truck down the road from me in a field with a visor and i just about bet its a lund visor but not sure I’ve thought about swiping it but i don’t wanna steal I don’t need the bad karma

I do not, I will have to snap a pic of it sometime.

There's a gmt400 that's been sitting beside a building near my house for years. It had a lighted visor, and a racer back cab fairing, that I noticed was gone a few weeks ago. Not sure if somebody stole them or what, but they looked pretty good. No idea who owns the truck, the build it's near has had several different businesses in it.

Damn, I would've taken the visor and Racerback lol.

 

[Donald Mitchell]

The original hood was created in 1969. It had a vent built in the rear opening that would open under acceleration. It was also ducted to fit around the air cleaner which was also special and had a seal to fit the duct . Truck hood will have none of this. The fourth pic is a cowl plenum induction , draws fresh air through the cowl vents. Started using this in nascar in the mid 60's

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[Donald Mitchell]

Sorry here's the 4th pic.

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[Supercharged111]

Despite you posting this wonderfully factual info, there are still those out there who believe hot air will escape from this location.

 

[Tim W]

Donald is 100% correct with out a dedicated air plenum the cowl will not work 100%. The key parts hood is fully open at the top and u can see daylight. When the engine is hot you can feel The fan blowing if you put your hand over the screen. Is it actually letting hot air out? I have no clue. The hood is "functional" it would just work better and correct if you built an air plenum .

 

[b454rat]

yes without the ducting that it won't work as a "cowl hood" should, but when driving down the road you can't tell me that air isn't going thru the radiator and out the hood.

 

[Supercharged111]

yes without the ducting that it won't work as a "cowl hood" should, but when driving down the road you can't tell me that air isn't going thru the radiator and out the hood.

Yes, we are telling you driving down the road air IS NOT exiting out the scoop. It's coming IN and, to some extent, stagnating flow through said radiator. Do you see road race cars using cowl hoods? There's a reason they don't.

 

[CrustyJunker]

He's right. Quick overview on unsealed cowl hoods...Not talking cars with proper air cleaner boxes with sealed baffles and all that good stuff.

Bottom of the engine bay is open. Moving at a decent speed - A lot of that air is being sucked into the cowl and going out the bottom. Hot air can only escape with convection when the vehicle is sitting still.

A fraction of vehicle aerodynamics, let's just focus on these - At speed, there's a high pressure zone right where the hood meets the windshield, and another one in the grille area. Low pressure behind the front bumper and under the hood. The fast moving air rushing under the vehicle helps this effect.

There's other crazy physics/voodoo/magic that vary from different vehicles and designs. But that's the least wordy I can be with it.

Again, this is un-baffled cowls...You can prove this science experiment yourself! Try taping a strip of something (maybe paper, card stock, or thin plastic) along the top edge of the cowl. At rest to low speeds, hot air will push the strip out by any fans running and/or heat convection. As you accelerate, it'll eventually vacuum down to the cowl entrance, or get sucked in if the opening is large enough. Pretty cool, right?

 

[b454rat]

Yah know, now that I think about it, when I had my 90 GMC with a 4” glass hood, in the winter with a dusting of snow, you could see snow go into the coal....dunno how remembered that from almost 25 years ago.....

 

[24 Karat Brown]

Yes, we are telling you driving down the road air IS NOT exiting out the scoop. It's coming IN and, to some extent, stagnating flow through said radiator. Do you see road race cars using cowl hoods? There's a reason they don't.

But if you have a TBI or carb wouldnt an open cowl hood make a sort of crude cold air intake with an open filter or lid flip? Seems like a cowl would be most functional in a city, low speeds and lots of idling. That way the heat has another spot to escape