Under Hood Heat

JARHEAD-JL

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I wonder if we can add the 392 Hood with the Hydro Guide system in our non V8 JLs?
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DHW

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Sorry, you are incorrect. I do not want to school you on thermodynamics (Heat, Radiation, Conduction).

But, I will give you some clues; the difference between the paint on the hood and underneath the hood, the energy (Heat source) optimal operating temperature and the entropy of the material involved.

You are free to do what you feel is best for you, each to their own, but please do not claim your mod as scientific fact. It is nothing more than a cool non functional modification.
Speaking of heat... DAAYYYUUMM! That was one scientifically sick burn!

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Headbarcode

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IIRC he used Frogzskin.
That kinda rings a bell. Thanks for the add, buddy!

HUGE “like” to this post! My experience in Florida heat and water is the same. Another concern I have, which stops me from cutting the hood under my Rubicon hood vents, is a bow wave washing over the hood when entering a water crossing with speed and momentum. Besides, as previously stated, my 2.0T ALWAYS operates within normal temperature limits during blazing-hot Florida summer weather.
Always happy to be of some use around here! I've gleaned so much info from you all, so it's a pleasure to return the favor.
 

flyer92

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Great discussion, and makes me wonder if there's a way to make the side vents more efficient, perhaps by modifying the baffles inside the engine compartment? I suspect these were designed to work optimally as-is, but just curious if anyone has fiddled with them yet. Would be a great improvement for all JLs, not just Rubis. Only concern, is that they'd put out so much heat, it might melt the plastic screen or adjacent fender flares.
 

Ronbo Ranger

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Been thinking about this more.
If only I knew an engineer who could design the baffles in an inlayed channel to the outside contours to capture water to a drain line.
In my opinion, Because the fake baffles are there, They should be functional instead of a decoration on my hood. But for the reasons I've read, I'm just going to live with the original design for now,
which btw still look Cool to me.. What's available on the market does not address water drainage to my knowledge.
 

JEEPIDON

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Sorry, you are incorrect. I do not want to school you on thermodynamics (Heat, Radiation, Conduction).

But, I will give you some clues; the difference between the paint on the hood and underneath the hood, the energy (Heat source) optimal operating temperature and the entropy of the material involved.

You are free to do what you feel is best for you, each to their own, but please do not claim your mod as scientific fact. It is nothing more than a cool non functional modification.
Well you can combinate any horseshit of thermodynamic variables that you like but I have checked this with engineers at Stellantis (my brother has been an engineer there for 30 years) and it is added for noise reduction. If you don't believe it, go to the Jeep JL accessories catalog and you'll see that if you order a new hood you can also order a "sound insulation pad" which is what this is for.

Hell, musclecars didn't even have pads under their hoods. I removed 99% of all vehicles (over 45) sound insulation pads and never had any issues with paint.

So now if you have fed your ego enough, show me an example of where I'm wrong. Actual photo of damage because the pad wasn't there.
 

SilverSurfer

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Well you can combinate any horseshit of thermodynamic variables that you like but I have checked this with engineers at Stellantis (my brother has been an engineer there for 30 years) and it is added for noise reduction. If you don't believe it, go to the Jeep JL accessories catalog and you'll see that if you order a new hood you can also order a "sound insulation pad" which is what this is for.

Hell, musclecars didn't even have pads under their hoods. I removed 99% of all vehicles (over 45) sound insulation pads and never had any issues with paint.

So now if you have fed your ego enough, show me an example of where I'm wrong. Actual photo of damage because the pad wasn't there.
No need to get emotional and insulting. It is simple facts at play here.

Let's say your engineer brother is correct that the hood insulation is only for noise reduction, we then have a problem to solve and that is; why does the "noise reducing" hood insulator material not show any signs of excessive heat, catch fire, melts, etc? Mmmm... It must be that it either absorbs or reflects heat (Energy).

Either way, absorb or reflect, the fact remains that the hood insulation is functionally not only for noise reduction.
 

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I wonder if we can add the 392 Hood with the Hydro Guide system in our non V8 JLs?
It would take some MAJOR re-engineering of the engine bay. The 392 intake is on the driver's side and meets the Hydro Guide system further inward so a lot would have to be relocated.
 

BDinTX

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niJL

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I've run my 2.0 JLUR in the 120+ degree weather that I live in for two summers now. No overheating issues.

The hood prop does get super hot, but it's a metal rod near a running engine.. That's why they put the yellow foam on there for you to grab it with.
 

JEEPIDON

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No need to get emotional and insulting. It is simple facts at play here.

Let's say your engineer brother is correct that the hood insulation is only for noise reduction, we then have a problem to solve and that is; why does the "noise reducing" hood insulator material not show any signs of excessive heat, catch fire, melts, etc? Mmmm... It must be that it either absorbs or reflects heat (Energy).

Either way, absorb or reflect, the fact remains that the hood insulation is functionally not only for noise reduction.
Well without getting too crazy I would say that the insulation is to withstand the environment it's in. Why would they build something that would melt, catch fire or self destruct that goes under a hood?

So: "Guess the engineers didn't know what they created and my brother and his colleagues (that he asked) are liars or just full of shit? I guess Jeep advertises this item as noise insulation in their catalog and parts no. in the repair manual to mislead people?

Some people just can't admit they just make shit up!
 

Headbarcode

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Just because your engine water temp is not over temp does not mean all the other electronic components under the hood are not experiencing them.
The radiator and thermostat control the coolant Temps to that 190ish range. Trust me many parts are getting hotter than that!
I've got a new jeep coming in a couple weeks.
I'll use some temp probes I use for testing to compare before / after Temps when I cut holes in my rubicon vent and insulation.
It's definitely a reality that there are distinct areas of the engine bay that see both higher and lower temps than what are seen in the water jackets. But under hood heat management has a lot of years of research, through trial and error, to develop and tweak the materials used on and around the ancillaries.

Modern diesels are the worst, as far as engine bay heat. It gets hot enough that regular rubber heater hoses don't last, so they typically get plumbed with silicone hoses that can handle the higher temperatures.
 

R00STER

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I am not a mechanical engineer, nor did I stay in a Holiday Inn, so I am not gonna throw out an unsubstantiated opinion on the heat capacity of the sound surpression mat on the underside of the hood......BUT I will say that SBT has a hood scoop solution that cold solve the problem and it has plugs for those concerned about water intrusion......pair it with their Cold Air Intake and it could be a slick solution for those with $700 burning a hole in their pocket.

Check it out SBT Hood Scoop

Cheaper than a 392 Hood.....and almost as cool (kinda).
 
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