Just purchased hood louvers

I found these on ebay for cheap what do you all think? $59.95 for the set. They measure 12inch by 12inch and the louvers are 4inch wide and 3/8inch high. 36 total louvers. 16 gauge cold rolled steel.

they look fine, if YOU like em, theyre excellant! PERSONALLY, i dig the 'riveted' look, reminds me of older aircraft and the mechanics that made shit happen.

make sure you post a 'completed' pic!

Yes I like rivets. I love old planes P51's and P47's I am going to paint them black and slap them in. Should I use 3M tape along with the rivets?

single/double sided tape will make it stand-off 1/16" or 1/8th". you may need that extra wiggle room due to hood curvature... so who knows! get your layout, do the cuts then see how they fit. 16 guage may bend enough to fallow the hoods curvature's, which would make it fit even better

Where are you gonna put them? Right behind the radiator fans would probably be best. Too far back and they'll push air down into the engine bay at highway speed, like those backwards facing cowl intakes.

I am going to put them towards the back of the hood by the windsheild between the hood supports. Due to there size that is in the only location I can place them. I do not have a problem with hightemps at speed and most of the heat comes from the manifold so I figure that is the best location for a hood vent.

chris420 said:

I am going to put them towards the back of the hood by the windsheild between the hood supports. Due to there size that is in the only location I can place them. I do not have a problem with hightemps at speed and most of the heat comes from the manifold so I figure that is the best location for a hood vent.

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That makes the most sense for their location.

make sure you get paint up in the louvers or there gonna rust. I would just run a bead of silicon around the edge and let it dry. that way you'll get a tight seal and it wont leave a residue or break down with heat.

Are those louvers aluminum?

I wanted to get some in stainless, and Run Cool has them but I didn't want mirror polished. I'll probably just go with Gen-Right painted aluminum for the cost.

chris420 said:

I am going to put them towards the back of the hood by the windsheild between the hood supports. Due to there size that is in the only location I can place them. I do not have a problem with hightemps at speed and most of the heat comes from the manifold so I figure that is the best location for a hood vent.

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The fella that did this writeup thought he knew where to chop holes in his hood too ...

http://www.oman4x4.com/hoodvents.htm

After he took the time and expense to test underhood temps .... he found different.

Engine bays are engine bays ..... The tranny tunnel will evacuate a certain amount of heat whilst the engine bay corners trap heat. Which explains the diagram in the link.


XJ's will always have a hot hood ... Its too close to the engine in addition to other reasons. A cowl hood helps somewhat in that regard because the extra height provides additional heat dissipation space.

Vents directly over the engine / manifold will allow the simple physics of naturally rising hot air - to escape .... but so will holes anywhere in the hood - at low speeds ...

Vents near the rear corners will allow heat out ... and vent the actual hotspots around brake boosters and whatever else is there.

Vents in the hood rear corner areas, are also more likely to provide a benefit at higher speeds too .... just takes some bonnet spacers and some taped on bits of wool to find out ....


edit: .... To see how well the corners provide a venting function during the hood spacer test ... Its a good idea to use a packer of some description, zip tied to the bonnet release cable - to prevent any unnescessary, induction issues at higher speeds ..... I just used a length of water pipe foam insulation tubing.

joe_peters said:

Are those louvers aluminum?

I wanted to get some in stainless, and Run Cool has them but I didn't want mirror polished. I'll probably just go with Gen-Right painted aluminum for the cost.

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X2 pretty much the cheapest option for high quality aftermarket louvers. but why not just get the unpainted ones to save a little?

austinaubinoe said:

X2 pretty much the cheapest option for high quality aftermarket louvers. but why not just get the unpainted ones to save a little?

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Yeah, but I don't like bare metal reflecting light on my hood, so I would have to paint them anyway, so for $10 difference on the Gen-Right I would get the painted.

I think I am going to have them powder coated. I have saved a few wright ups from other people that explained were I should place my hood vents. A few things made me not to decide on were I should place my hood vents based on there extensive research that used wool taped to the hood and video while driving on were the air moves accross the hood ect. I do not have a hot rod so all the write ups I have seen or saved on hood vent placement do not work for me. My jeep will be diving into rivers with water rushing over the front clip and hood so if I were to place the hood vents in the front of the hood water would rush in and could apply drag to the fan lowering my horse power causing me to posibly not make it through the river or downing out my alternator and stalling my jeep half way through the river. At trale spead heat is above the manifold causing fuel to boil and possible vapor lock so the best placement in my mind is the back of the hood. At speeds air is forced throught the grill and upwards by the fan so foward and up would mean the best placement would be the back of the hood because it would cause a vacume effect pulling the air backwards up and out.

chris420 said:

I think I am going to have them powder coated. I have saved a few wright ups from other people that explained were I should place my hood vents. A few things made me not to decide on were I should place my hood vents based on there extensive research that used wool taped to the hood and video while driving on were the air moves accross the hood ect. I do not have a hot rod so all the write ups I have seen or saved on hood vent placement do not work for me. My jeep will be diving into rivers with water rushing over the front clip and hood so if I were to place the hood vents in the front of the hood water would rush in and could apply drag to the fan lowering my horse power causing me to posibly not make it through the river or downing out my alternator and stalling my jeep half way through the river. At trale spead heat is above the manifold causing fuel to boil and possible vapor lock so the best placement in my mind is the back of the hood. At speeds air is forced throught the grill and upwards by the fan so foward and up would mean the best placement would be the back of the hood because it would cause a vacume effect pulling the air backwards up and out.

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Good to see some thought has gone into your vent needs.

IMHO vents at the front are detrimental for general use anyway ... as a lot of air that would normally be pushed to the rear of the engine bay ... escapes at the front ... which is good for radiator airflow but not a lot else.

If the primary role of the vehicle is for trail work ... then vent decisions should be based on that .....

Trail and highway use requires some additional thought .... and some concessions have to be made to get a balanced result.

"vacume effect pulling the air backwards up and out" ... works very well - at all speeds when venting from the area of the, hood rear corners.

At speed there is downward airflow in front of the windscreen ..... Its why some people put airfilters/intakes in with the wiper motor ... and why the factory has the cabin vent intake there.

Anybody with a cowl hood or spaced hood ... can watch woollen telltails mounted between the wiper arms/ rear edge of the hood ... disappear into the engine bay once speeds get over 20 odd mph ... unless theres a cessna propellor cooling the radiator ...

In the end its your vehicle and you can only do what you think is best. Since nobody in 25yrs has ever bothered to provide sufficient and accurate data for best venting arrangements ... We can only go by forum popular opinon, vent company glossy advertising, limited factual vehicle tests, The size and fitting requirements of the vents chosen ... and some home grown experiments ......... oooops ... and whether they look cool

chris420 said:

My jeep will be diving into rivers with water rushing over the front clip and hood so if I were to place the hood vents in the front of the hood water would rush in and could apply drag to the fan lowering my horse power causing me to posibly not make it through the river or downing out my alternator and stalling my jeep half way through the river.

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If water is going up over your hood your fan is at least half way submerged anyway, and if your XJ is pre97 your alternator is under water already too. are you planning on running these with the openings facing forward? as long as they are facing back towards the windshield any water that goes in from a splash over is going to be minimal.

I have noticed when I am going through rivers the water is being pushed and does not seem to go up to high in the engine bay. Maybee the water will not get through the vents if under water but I feel any attempt to keep water out of the engine bay is better than letting more in.

chris420 said:

I have noticed when I am going through rivers the water is being pushed and does not seem to go up to high in the engine bay. Maybee the water will not get through the vents if under water but I feel any attempt to keep water out of the engine bay is better than letting more in.

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Wouldn't the water just go straight through the radiator?

chris420 said:

I have noticed when I am going through rivers the water is being pushed and does not seem to go up to high in the engine bay. Maybee the water will not get through the vents if under water but I feel any attempt to keep water out of the engine bay is better than letting more in.

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winkosmosis said:

Wouldn't the water just go straight through the radiator?

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Surprisingly ... as long as a steady forward momentum is maintained ... very little water will fill the engine bay.

The front of the vehicle will act just like a boat bow ... albeit a leaky boat ...

Playing in big puddles will allow eventual water levels to fill the engine bay tho.

Common down here to use a small tarp to cover the vehicle nose for water crossings ... altho clutchfans and electric fans make the tarp less of a nescessity compared to old style fixed fans.

Always wise to stop and let the vehicle cool before entering water too ... as it prevents cracked brake drums, warped brake discs, water sucked into diffs ... and anything else that might suffer from sudden temp changes.

Proper water crossing: http://www.youtube.com/watch?v=PW9gNaPDghw

^ Remember, this is Iceland. They think Bjork is normal here...