the best location for functional hood vents and ambient air intake?

[mmag1982]

I am thinking of the best location for hood vents .

I purchased aluminum louver panels from synergy suspension with the following dimensions:

- long ones: 15.375" L x 4.0" W
- the square short ones: 7.71" L x 7.96" W

My objectives are:

1- to create the best possible heat dissipation for the ridiculous under hood temp. using the long vents. The theory i know is that hot air is lighter than cold air so it should always flow out of the vents.

2- to use one of the square vents as a functional cold/ambient air intake for my AEM intake setup. What i have in mind is to create an insulated enclosure around the filter using the same material used for hood insulation and to have the vent directly above the filter as much as possible. This way The filter can easily suck air at ambient temp

So please tell me what you think of this preliminary locations in the picture using template paper. Those location clear the hood support panels.

Would this setup " functionally " work ? which direction should the louvers face , i am thinking the curved slots should face the windshield instead of facing the incoming air rush.

 

[bigalpha]

Out of curiosity, are you trying to lower under hood temps to solve an overheating problem?

 

[mmag1982]

not specifically overheating, but in traffic and slow stop and go driving in summer where i live ( 40deg Celsius ), i can feel huge amounts of heat building under the hood. and the auxiliary cooling fan in these conditions is struggling to keep the temp at 100deg Celsius.

Plus of course performance degrading as the intake is sucking very hot under hood air.

 

[urban yan]

http://www.go.jeep-xj.info/HowtoBonnetVents.htm

 

[mmag1982]

thanks urban yan for the link, exactly what i needed, but what do you think of using the vent directly above the filter for ambient air intake?

 

[XJCasper]

Is there a way to block incoming water from elements such as rain or puddles?

 

[SKUNKAPEXJ]

Sent from NEVADAfornia

 

[bigalpha]

In my 88, my stock airbox has a small compartment that nestles behind the driver headlight so it doesn't (shouldn't) pull hot air in from the engine bay.

Is yours set up like this?

 

[Talyn]

In my 88, my stock airbox has a small compartment that nestles behind the driver headlight so it doesn't (shouldn't) pull hot air in from the engine bay.

Is yours set up like this?

I don't know what year his is or when they changed it, but my 2000 air box had a hole in the air box.. that opened to a piece of sheet metal behind the head light.

 

[Dr. Dyno]

The best place for hood vents is as near the front as possible where there's a negative pressure area to pull hot air out of the engine compartment when travelling at speed. For the same reason, that's the worst place to position your air intake.
The air intake needs to be in a positive pressure area that's exposed to ambient air. The two best places for that are the heater vent cowl area and the areas just above and below the front bumper.

 

[hubs97xj]

I don't know what year his is or when they changed it, but my 2000 air box had a hole in the air box.. that opened to a piece of sheet metal behind the head light.

FWIW, my friend's 96 has that cut-out, with a plastic cover over it; my 97 does not. No duct on the 96, just an OEM plastic cover for the hole in the sheet metal.

 

[techno1154]

FWIW, my friend's 96 has that cut-out, with a plastic cover over it; my 97 does not. No duct on the 96, just an OEM plastic cover for the hole in the sheet metal.

I keep saying the 1996 is the Red Headed step child. My '96 do not have the cut out but the '94 I once owned had it.

I agree with Dr.Dyno. The best location to get rid of the hot air is towards the front of the engine bay just behind the radiator. You could see the smudge on the under side of the engine cover as a result of the fans spinning every thing up there.

 

[O-Gauge Steamer]

For getting rid of heat, it depends on how fast you are driving. Just aft of the header, nearest the front edge of the hood, is the best place to vent heat at highway speeds, nearer the back of the hood is better for low speeds.

IMO the best place for the intake is either the cowl or, better still, the front end.

 

[mmag1982]

ok , location of the heat vents are clear, but i'm still not clear on the intake, 2 thoughts:

if i place an intake pipe in the cowl area feeding the air filter box, the total length of the system up to the throttle body is just too long.from cowl to front left corner through filter to mid of engine bay, shouldnt that have a negative impact on throttle response? vs. air box just having an opening above it to atmosphere.?

the other thing is that yes the front of the hood will be under -ve pressure at low speeds, but at higher speeds i think everything will be under +ve pressure?

and does turning the louvres to face the incoming air stream like a scoop help?

 

[seanyb505]

Best thing to do is tape pieces of yarn to the hood and drive around making notes. At what speed do you spend most of your driving? Pay special attention there. Also fwiw, my Feb 97 has the cut out and only had a piece of plastic screwed on.

 

[bigalpha]

FWIW, here are some pics of my air box.

 

[mmag1982]

bigalpha, that is right in the back of the headlight isn' t it? it seems the headlight will be blocking any incoming air this way,

I think i'll go for the cowl location using a spectre kit,

 

[bigalpha]

Yes, it is right in the back of the headlight.

 

[souske]

My 96 had the plastic cover, and the airbox "snorkel" was quite short.

I was able to piece together a box from an older HO, and removed the cover.