Cooling efficiency of different hoods?

[dcmdon]

How could something like this NOT improve circulation under the hood? If I had a winch on the front, I'd definitely be trying something like this.

https://carbonfiberhoods.com/2019-2...t-duraflex-demon-look-hood-1-piece-ed_116496/

Something like that would pressurize the engine compartment. This would decrease the pressure differential between the front and back of the radiator. This would decrease flow through the radiator.

The ram air intake on the 392 goes directly to the intake via a snorkel. It didn't just dump the air into the engine compartment.

If you want to increase radiator efficiency and improve cooling, you want a vent that will EXTRACT air from the engine compartment. This will lower the pressure and increase the pressure differential between the front and back of the radiator.

Based on some eyeball engineering, a functional set of Rubicon vents might work. But I don't know. Someone must have done a CFD analysis of a Wrangler. That would be interesting to see.

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[dcmdon]

Were you able to make any quantitative comparisons before and after?

This is very difficult to do because you would be fighting engine controls attempting to maintain the temp in a certain range. For example, the hood could help a lot. But you wouldn't see it because its hidden by the fact that the thermostat closes at a certain temp and the motor simply isn't going to cool below that temp.

Or it could pressurize the engine compartment and disturb flow though the radiator. You might not notice it because the fan kicks on to keep the temp in the normal range.

If you wanted to get all scientific about it you cold disable the fan and remove the thermostat. Then drive it at a certain speed over a certain road. Then quickly swap hoods, repeat, and note the temp differences.

 

[dcmdon]

My 2021 Gladiator is a diesel 3.0. If you look at the forums for these there are multiple posts about heat issues and Jeep not providing any solutions.

The overheating problems happen only under 2 specific conditions.
1) hot - You've got that covered living in AZ
2) towing a difficult load, usually up hill - if you dont' tow large loads on the highway for long distances, this doesn't matter.

So if you are not towing in a really stressful way, any kind of cooling improvement mod is pointless.

 

[dcmdon]

true. i was not thinking about the diesel. hood vents might still not be the best idea. it boils down to where the heat comes from. there are exhaust wraps, coatings, thermal barriers, etc to truly help keep things cooler… a lot of things outside of vents. ina.. honesty, many people get vented hoods just cause they look cool. they pay absolutely no attention to even vent placement which is important.

You are combining 2 issues. Under-hood temp and coolant/oil temps. Diesels have issues with coolant and oil temps getting high. Exhaust wraps and thermal barriers will do a great job of reducing underwood temps, but won't do anything to lower coolant and oil temps.

 

[MPMB]

If you wanted to get all scientific about it you cold disable the fan and remove the thermostat. Then drive it at a certain speed over a certain road. Then quickly swap hoods, repeat, and note the temp differences.

In racing we found out that the fan and the assembly, in most cases, actually impedes cooling. Where the fan and the housing mounts against the radiator ends up blocking the air that goes through it.

Removing it resulted in a 10-15* drop.

I think the best bet would be to cram in a larger radiator.

 

[dcmdon]

In racing we found out that the fan and the assembly, in most cases, actually impedes cooling. Where the fan and the housing mounts against the radiator ends up blocking the air that goes through it.

Removing it resulted in a 10-15* drop.

I think the best bet would be to cram in a larger radiator.

I agree. Our race bikes didn't have fans. But we weren't stuck in traffic. The general consensus is that a larger radiator will work. The problem is that its not easy to do. Its not like the old days where you had plenty of room to put in a larger radiator. There is a sandwich of oil coolers, transmission coolers and radiators up there.

 

[Rusty PW]

The location of vents makes a big difference. On my Nismo. No vents in the hood. I could see water temps in the 250 range, and oil in the 270 range after a 30 minute session. I added a center vent right behind the radiator. The temps dropped to 220 water and 220 oil after a session. I added 2 other side vents. Those really don't do much when moving. But let out the heat sitting still. If the vents are too far towards the windshield. They will not vent properly. The base of the windshield is a high pressure area. I opened up the vents on my JTRD hood. didn't see much difference. Think if it was a center location, behind the radiator. you would see a difference. The 392 style hood would do nothing for cooling. Instead of letting air out. It would be pushing air in at the wrong location.

 

[Kevlarr]

You keep saying “In racing “. I’m not planning on entering any races. My concern is high temps when I’m crawling over boulders and rough terrain. Again waaaay over thinking this thing. It’s entertaining though. I enjoy the Jeep owner overachiever discussions. Haha.

kR

 

[Kevlarr]

Yup. What I’m talkin about…

 

[Sinner05]

How could something like this NOT improve circulation under the hood? If I had a winch on the front, I'd definitely be trying something like this.

https://carbonfiberhoods.com/2019-2...t-duraflex-demon-look-hood-1-piece-ed_116496/

Hood pins required…. Mehhh. Lol

 

[RS3]

These are not for venting as much as they are for providing air but I have been considering these for my JTRD. Not a big fan of the look but they might help in providing some air to cool things down. https://www.northridge4x4.com/part/...lH-eMRbUb9XbcSS_strWDRokgXbM46n4aAhTOEALw_wcB

 

[Jaxmax]

The Wrangler 392 hood which is the same as the Mojave hood has a Hydro-Glide system which provides cold air direct to air cleaner and has openings directing air directly towards the rear on both sides of engine, with rubber flaps that hang down and shut off vents when not moving and allow radiator pressure to be factory. Not a cheap mod, but one I am planning on doing in future.
I believe any cooler air entering the rear of engine compartment will help a little bit and possibly cool the air going under the body tub......Jack

 

[PJZ]

AEV made a heat reduction hood for the JKs and it had a large vent just behind the front edge. They like to test everything and here is their opinion -
The central vent of the Heat Reduction Hood is positioned to take advantage of the low-pressure area created at the front edge of the Hood when the vehicle is in motion. Since air moves from high pressure to low pressure areas, the placement of the center vent causes cooler outside air to be drawn through the radiator and up through the Hood.

Essentially cutting the Rubicon vents is doing the same thing albeit via our shade tree engineering and could be a little far back compared to the AEV vent. Mine have been cut for a couple months and no issues, but no noticeable temp differences. Think @dcmdon makes a good point about the computer keeping everything in range.

In another thread there is a post saying Insane Diesel is building a bigger radiator/cooler set up for our diesels. That will be the ultimate fix. Lots of posts on early adopter oil coolers as well.

 

[mrmo]

https://smile.amazon.com/DV8-Offroad-Replacement-Designed-Gladiator/dp/B08743KV9C/

Something like this?

Kevin

Thats a little salty, but I have also been thinking about it somewhere along the line, after I spend the rest of my life's savings on mods A Mojave or Rub hood are cheaper arent they? You could make the Rub vents active without too much trouble if you have any fab skills at all. Only thing is if water can get into the engine area, what starts happening with electronic parts?

 

[Rusty PW]

Thats a little salty, but I have also been thinking about it somewhere along the line, after I spend the rest of my life's savings on mods A Mojave or Rub hood are cheaper arent they? You could make the Rub vents active without too much trouble if you have any fab skills at all. Only thing is if water can get into the engine area, what starts happening with electronic parts?

My JTRD has sat out in a down pour without any issues. It just washes off some of the dust under the open vents.

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