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  #1  
Old April 18th, 2018, 22:50
Tankerblade Tankerblade is offline
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Hood vent design debate

So, on my laundry list of stuff to do to my pile, I'm planning on doing some hood vents to dissipate some heat.

So far most vents are louvered and angle back and not all that good looking IMO. So found a pic online of a plasma cut design.

I like the design and idea of it.

However, I question the purpose of the angled back louver. With it angled back does it help force air down around and out the bottom while moving? Or create a venturi affect and help suck hot air out through the top while moving?

How would a set like the picture given do? Obviously anything is better then nothing, just curious as to the design of louvers and its effects on air/heat transfer.

Also, live in AZ. Dont care about rain and water because well what's rain? Lmao

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  #2  
Old April 19th, 2018, 08:16
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freerider15 freerider15 is offline
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Re: Hood vent design debate

What I really don't get is:

- Why so many people feel the need for hood vents, when if in proper working order they're not needed
- Why so many people seem hellbent on putting hood vents in that let any precipitation fall right down in/on the engine

Any time I see hood vents (that aren't drain pan'd), hood holes (hole saws) or louvers on the hood itself I just have to laugh.
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  #3  
Old April 19th, 2018, 08:37
Heavyopp Heavyopp is offline
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Re: Hood vent design debate

Quote:
Originally Posted by freerider15 View Post
What I really don't get is:

- Why so many people feel the need for hood vents, when if in proper working order they're not needed

Although he doesn't say it here he's running a 2001 XJ -- that means those silly pre-cats under the hood -- He will experience heat soak causing the fuel to vaporize while shut down for short periods -- Happened to me just the other day while filling up with gas -- was 70 degrees out -- Jeep wouldn't start till I opened the hood and gave it 5 minutes to cool down

- Why so many people seem hellbent on putting hood vents in that let any precipitation fall right down in/on the engine

I do agree with this -- doesn't make sense to me either -- the TPS alone is right there up on top exposed to the rain

Any time I see hood vents (that aren't drain pan'd), hood holes (hole saws) or louvers on the hood itself I just have to laugh.
I'm personally thinking of doing some sort of cowl hood -- may build a rain gutter if needed -- in the short term I must get manual control of my electric fan -- It has to run if I'm shutting down for a few minutes to get the heat from the pre-cats out
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Old April 19th, 2018, 08:55
XJ_NorCal XJ_NorCal is offline
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Re: Hood vent design debate

I'm interested in hearing the pros/cons of hood vents/louvers. I've been considering them but haven't pulled the trigger because I haven't had issues running hot...yet.
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  #5  
Old April 19th, 2018, 09:04
RCP Phx RCP Phx is offline
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Re: Hood vent design debate

Quote:
Originally Posted by freerider15 View Post
What I really don't get is:

- Why so many people feel the need for hood vents, when if in proper working order they're not needed
- Why so many people seem hellbent on putting hood vents in that let any precipitation fall right down in/on the engine

Any time I see hood vents (that aren't drain pan'd), hood holes (hole saws) or louvers on the hood itself I just have to laugh.
This ^^^ I been here for 53 yrs now and it gets about the hottest in the nation. I've towed my #3500 trailer 1000's of miles and one summer I towed a #12,000 contruction trailer to the dump, yes it was showing +210* but it held!
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  #6  
Old April 19th, 2018, 09:07
RCP Phx RCP Phx is offline
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Re: Hood vent design debate

I forgot to say that I'm notorious for crawling w/ my A/C on and never shutting my motor off when I'm on the trail!
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  #7  
Old April 19th, 2018, 09:14
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DaJudge DaJudge is offline
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Re: Hood vent design debate

Quote:
Originally Posted by freerider15 View Post
What I really don't get is:

- Why so many people feel the need for hood vents, when if in proper working order they're not needed
- Why so many people seem hellbent on putting hood vents in that let any precipitation fall right down in/on the engine

Any time I see hood vents (that aren't drain pan'd), hood holes (hole saws) or louvers on the hood itself I just have to laugh.
Mine didn't make a difference in engine coolant temps but made a huge difference in under hood temps at slow speed.
Also, if your engine can't handle a little moisture you have bigger issues than some rain getting on it.
Hardly any water gets through my Lebaron vents.
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  #8  
Old April 19th, 2018, 11:40
Heavyopp Heavyopp is offline
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Re: Hood vent design debate

Quote:
Originally Posted by RCP Phx View Post
This ^^^ I been here for 53 yrs now and it gets about the hottest in the nation. I've towed my #3500 trailer 1000's of miles and one summer I towed a #12,000 contruction trailer to the dump, yes it was showing +210* but it held!
If I recall correctly none of your XJ's have the cali emission pre-cats under the hood

You must take them into consideration...

When my Xj wouldn't start the other day the temp gauge showed just under 210 -- usually I'm almost a full notch below 210 -- Keep in mind I just started driving this jeep over the winter -- The day that happened was the warmest day I've driven it in and it was only 70-75

I was watching the gauge because I did have the heat soak issue in mind -- and it happened

On the 2000,2001 just turning on the AC does not automatically mean the electric fan runs -- at least not on mine
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  #9  
Old April 19th, 2018, 11:42
Rockwood Rockwood is offline
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Re: Hood vent design debate

Caveat: I do not have any hood vents.



Quote:
Originally Posted by freerider15 View Post
What I really don't get is:

- Why so many people feel the need for hood vents, when if in proper working order they're not needed
- Why so many people seem hellbent on putting hood vents in that let any precipitation fall right down in/on the engine

Any time I see hood vents (that aren't drain pan'd), hood holes (hole saws) or louvers on the hood itself I just have to laugh.
Biggest problem I have with mine is desert crawling with wind and the AC running. The wind gets high enough to stall the air through the fan (or slow it enough to cause issues). Getting hot air out of the engine bay and giving the reversed airflow somewhere else to go may be helpful.

The moisture on the motor shouldn't be an issue. A little dielectric grease on the connectors under the vents should be more than sufficient to overcome any wear/tear in the factory weatherproofing.

Quote:
Originally Posted by Tankerblade View Post
So, on my laundry list of stuff to do to my pile, I'm planning on doing some hood vents to dissipate some heat.

So far most vents are louvered and angle back and not all that good looking IMO. So found a pic online of a plasma cut design.

I like the design and idea of it.

However, I question the purpose of the angled back louver. With it angled back does it help force air down around and out the bottom while moving? Or create a venturi affect and help suck hot air out through the top while moving?

How would a set like the picture given do? Obviously anything is better then nothing, just curious as to the design of louvers and its effects on air/heat transfer.

Also, live in AZ. Dont care about rain and water because well what's rain? Lmao

Sent from my SM-G950U using Tapatalk
The louvers are for venturi effect. With the slight upward slant of the hood, the flat holes may actually introduce air pressure behind the radiator at speed (bad).

Quote:
Originally Posted by RCP Phx View Post
This ^^^ I been here for 53 yrs now and it gets about the hottest in the nation. I've towed my #3500 trailer 1000's of miles and one summer I towed a #12,000 contruction trailer to the dump, yes it was showing +210* but it held!
You towed a 12,000lb trailer with your Jeep? My condolences.

Towing/highway speeds aren't where my Jeep has beeped at me from overheating. It's always been on long hill climbs at low speed with the AC on.





That being said: I did notice a significant decrease in coolant temps using the factory recommended 10w30 over 10w40. If you're running heavier oil, try going to factory fill (assuming sufficient oil pressure) and see if it helps. Between that and a ZJ fan clutch, I haven't had any issues with temperatures and the auxiliary fan rarely turns on.
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  #10  
Old April 19th, 2018, 19:25
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blubullett blubullett is offline
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Re: Hood vent design debate

As said above, the raised/angled part of the louvers causes a venturi effect to help pull the heat out of the engine compartment. I have the RunCool large high flow louvers. I do not believe they really made much of a difference in water temp but they did make a large difference in under hood temps. You can see the heat rising from them any time you are stopped. I haven't had any water problems from them and my Jeep sits outside in the rain all the time. Would I do them again? Yeah. Did they make a huge difference? Not really.
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  #11  
Old April 19th, 2018, 19:28
Tankerblade Tankerblade is offline
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Re: Hood vent design debate

Quote:
Originally Posted by freerider15 View Post
What I really don't get is:

- Why so many people feel the need for hood vents, when if in proper working order they're not needed
- Why so many people seem hellbent on putting hood vents in that let any precipitation fall right down in/on the engine

Any time I see hood vents (that aren't drain pan'd), hood holes (hole saws) or louvers on the hood itself I just have to laugh.
Ha coming from someone who lives in colorado....

I live in az. Temps in the city reach 125ish. Couple that with stop and go traffic on the freeway on a massive black heatsink, the piss ant cooling system can not effectively handle it.

It can not be debated otherwise that 4.0s produce a massive amount of heat and with such a small engine bay, the transfer of heat is not as effective as it should be.

So the fact that you scoff at releasing heat more efficiently baffles me. As well as some notion of needing catch pans. By your comment it seems like engines should never see water, hope you never drive in the rain or wash the engine.

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  #12  
Old April 19th, 2018, 19:47
Tankerblade Tankerblade is offline
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Re: Hood vent design debate

Like others have said, sure it may not have helped water temp, but it certainly helps underhood temps. Which can only help the cooling any other system run cooler and provide a longer life, not to mention the heatsoak issue that plagues these jeeps...oh wait hood vents couldnt help that could they?

Now unless one has a absolutely perfect cooling system,or lives where it snows constantly then props to you.

I appreciate the input rockwood and blubullet. I figured it was for the venturi effect but did not think of the reverse airflow situation.

Honestly, my concern with these vents is not for driving. Its main and sole pupose in my eyes is for underhood temps once the damn thing is shut off. Im tired of a heatsoaked engine bay making my life miserable and its not even 100deg yet.
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Old April 19th, 2018, 19:51
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freerider15 freerider15 is offline
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Re: Hood vent design debate

Quote:
Originally Posted by Tankerblade View Post
Ha coming from someone who lives in colorado....

I live in az. Temps in the city reach 125ish. Couple that with stop and go traffic on the freeway on a massive black heatsink, the piss ant cooling system can not effectively handle it.

It can not be debated otherwise that 4.0s produce a massive amount of heat and with such a small engine bay, the transfer of heat is not as effective as it should be.

So the fact that you scoff at releasing heat more efficiently baffles me. As well as some notion of needing catch pans. By your comment it seems like engines should never see water, hope you never drive in the rain or wash the engine.

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You have hot temps, that's cute. Try hard incline's going up and down passes. Makes "hot dry temps" seem laughable.

But please, tell all you know about how the engine was designed, tested, and how your fluid dynamics calculations and simulations have worked out.

Sorry, but there are few hood vents out there that are worth a sh*t.

And yeah, I've known plenty of AZ and SoCal folk (lived in SoCal for a brief stint myself) with lifted rigs that don't have issues.

So tell me, the engine should have no problem seeing water on top of it? Now, how does what work when they came from the factory with wheel well liners, a hood, and more to prevent water intrusion? Last time I checked, none of the electrical fittings were water proof. Want to guess how I unfortunately know?

The heatsoak with the precat system can largely be solved with the heat shield that should still be next to the intake manifold and surrounding the injectors (I own a 2001, and know several that do).

But no, by all means, throw holes in your hood...hell take the hood right off!
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  #14  
Old April 19th, 2018, 19:52
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freerider15 freerider15 is offline
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Re: Hood vent design debate

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Originally Posted by DaJudge View Post
Hardly any water gets through my Lebaron vents.
Bit of a difference between Lebaron (e.g. OEM) and the "imma throw some CNC's mesh sh*t on my hood!"

And yes, there are several areas the 4.0's really don't like getting wet consistently.
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Old April 19th, 2018, 19:54
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freerider15 freerider15 is offline
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Re: Hood vent design debate

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Originally Posted by Tankerblade View Post
Its main and sole pupose in my eyes is for underhood temps once the damn thing is shut off. Im tired of a heatsoaked engine bay making my life miserable and its not even 100deg yet.
So, why not install an electric fan bypass?

How about a better than OEM pump?

How old is you radiator?

When's the last time you stripped the system down and did a full block flush?

If you're not overheating, then why the **** are you concerned?

It's an engine...it gets hot.
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