Another Hood Vent Option

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Couldn't agree more Maleficio.

As part of the endless, ad nauseous research that I did on this particular project, I learned all about air pressure differentials and creating the desired vacuum effect by raising the front of a hood vent and lowering the back. The picture below was another design inspiration for my project and shows a slight indention at the tail end of the hood vent.

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Ultimately, it's all going to come down to the highway test I mention above. I sincerely hope that all of this effort wasn't wasted on some elaborate rain port ;)
 
Thirsty said:
Couldn't agree more Maleficio.

As part of the endless, ad nauseous research that I did on this particular project, I learned all about air pressure differentials and creating the desired vacuum effect by raising the front of a hood vent and lowering the back. The picture below was another design inspiration for my project and shows a slight indention at the tail end of the hood vent.

View attachment 1422316

Ultimately, it's all going to come down to the highway test I mention above. I sincerely hope that all of this effort wasn't wasted on some elaborate rain port ;)
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I hear you. The problem with hood venting comes down to aerodynamics. It's easy to see a reduction in flow over the hood because the hood's leading edge acts as a foil.

Placing vents near the rear of the hood is useless, even if designed to be a venturi.
 
Marine7 said:
I'm not sure, nor do I care, where you got your degree from, but you sure as he#* don't know jack about hood vents. I've been putting vents like this in for years, and this will work fine. And, this vent doesn't allow as much rain in as one would think.
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Relax, partner. I love your work. So clean. However, it will only work in a parking lot as you run for a case of beer.

It is not a venturi. Though it can be transformed into a venturi.
 
Very kewl. Wouldn't the orientation of the mesh satisfy some of the poindexter rhombus that appears to be sought after? Looks like on the Merc it's set up as described ideal? Would also recommend trimming back the hood insulation thingy up to at least the yellow line from front to back..it will be out of visual and will keep it from filling up like a diaper as easily...also would go with a silicone or similar sealant to protect the edge, hopefully adhere it and keep it from flapping about...from what I've read here that insulation didn't come on all 80 series world wide..I would be concerned the RHD couple inch strip along the edge would lose it's integrity and turn in to a flap flap as well..totally hack so .02 for what it's worth..keep posting great thread
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My old Porsche 928 was suffering from power loss during the summer months. I wrapped the intake tubing with heat-reflective tape and it solved the problem.
 
In the last few minutes of reading these posts I had never heard the word venturi used this many times. Nor will I probably ever will so as long as I walk this earth.
 
There is a differance between a hood vent, and a forced air system (ala hood scoop). And your exactly right, the only place he will see a differance is the parking lot. That's because a vent is to dissipate heat at LOW speeds, not under throttle where the air speed will cool it down. Plus a vent isn't designed to increase power at all, unlike the forced air system your referring to.
 
Last time I heard venturi was I think back when I was into rotaries and was looking at weber carbs. To the OP, the design looks great and should function fine as a vent. I move plenty of new commercial vehicles, armored vehicles and work class vans, lots have flat vents like that on the hoods. I had even looked at maybe getting some of the vanity grilles from those models for my 80. The LC is not some supercar running at 200+mph. If it works as heat management for some quarter of a million dollar piece of equipment, I think it will be fine for the LC.
 
Hot Damn @Thirsty - you did a fantastic job - it looks like it came that way from the factory! I'm digging it!

Venturi, venturi, venturi!
 
Many thanks NLScooby!

dirtyboots - I had to laugh when I saw your comment about changing the orientation of the mesh. I'd originally planned to do just that with the Brabus design which is why I only bought one scrap "sheet" of the wire mesh in a 6" x 36" size with the mesh design running lengthwise. My plan was to cut two pieces of mesh at 6" lengths each and then join them under the middle-most slat between the vents, enabling it look exactly like the Brabus. When I had to change to the S2000 design, I was kinda ready to be done so I just used what I had which is why the mesh has the orientation that it does. I figure if the emblem tape ever gives out or some sh*t-for-brains slams a fist into it to see how sturdy it is, I'll just order more mesh and change the orientation.
 
I had a very strong feeling the orientation was about mesh supply on hand...also failed to compliment the edge of the cut, that is mighty fine fiddlin'...3m makes some unbelievably strong metal adhesive (about 50 different varieties with as many applications) that would reinforce if not replace the emblem adhesive..if I was brave I would have used it for my diff armor instead of my hideous welding job just to see if it would hold..might also seal up the edge of the hood mat, that was meant to be a more serious suggestion..Venturi was also discussed on an exhaust thread in the diesel section recently more Venturi!
 
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Well.....it looks my lesson in humility and perseverance with this project isn't over just yet. I apparently do gotta have more Venturi.

We had an 85 degree day this week so I decided to do the highway test I'd mentioned before, taping a magnetic HVAC filter door cover over the top of the vent to seal off the airflow as well as taping the hood liner piece of insulation I'd cut out back into place to keep the engine heat from melting the magnetic cover. I then cranked up the AC and headed out on the freeway, trying to stay at or above 80 mph. After 20 miles or so, the scan gauge crept up to a max of 193 and stayed there. I then pulled off the highway, removed all the taped pieces and headed back out. After another 20 miles, the temp crept up to a max of....(sigh).....193. Not one degree of difference. So yes, I apparently just spent all of this time on a hood vent only to have a very elaborate rain port.

On the bright side, the temps here in Dallas ain't gettin any lower any time soon so I'm glad to know now instead of in July or August. I think at this point, I'm going to hack up an aftermarket hood vent and mount it under the hole in the hood to create the negative pressure just past the front lip as Maleficio suggested and then go run another test. Something like in the pic below.

Under Hood Vent.webp
 
I wouldn't worry about your litmus test of 193, that is so close to thermostat temp that I would just say your truck is operating normally. Wait until you have 100+ degree days and you would normally see over 200 degree temps and check it then.

Venturi, smenturi, while I am all for proper design, CAD, wind tunnels, air flow, etc, there is a point where common sense reigns supreme and on a truck that is shaped like a bread box and that has a big flat hood, if you cut out a 1ft/sq hole above the exhaust manifold there is no way you are not going to let hot air out.

I have some vents on my black truck that look to be about the same size and about the same position and they let heat pour out while sitting and if you look at them on a hot day while driving you can see the heat waves just above the hood so hot air is also coming out while moving.

This looks great and I am sure will help on those crazy 100+ degree Texas days!

Oh and I have mine done on both sides and took it through the drive through car wash today completely expecting some water issues with the ignition but came out with zero problems.


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"I just want to say one word to you. Just one word. Are you listening? Plastics Venturi."



After bucketman's post, I decided to check the temp again with the scan gauge and even on the mid 90s weather we had recently, I'm still capping out at 193 which is a good sign. Will keep checking, though, as we inevitably creep unto the 100s and will probably do another vented vs. non-vented test.
 
The hood vent is cool and all (it does look cool if done right), but why not just install an electric fan and or a scoop over the wheel well or someplace. I put an electric fan in front of my radiator to help, works great and it's easy. I just had an ARB air pump installed for my lockers in the engine bay, so the stock injector fan was split to also pull in air to cool the pump so it does not get to hot.
 
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