Originally Posted by extrashaky

You're thinking about it backwards. If you force air through the hood down into the engine bay with a scoop, you will create backpressure inside the engine bay that will make the radiator less effective. Air should come in through the front grille and be dispersed out through the bottom (or hood, if you install vents).

Think about it like this: You have an "in" door and an "out" door, and you want to get a lot of people through as fast as possible. If you tell people to go in through the "out" door, they'll jam up the people coming from the opposite direction, and fewer people will be able to flow through the "in" door. You'll move fewer people through. Likewise, if you push air through your hood, it will jam up air coming through the "in" door of your grille, potentially causing less air to flow over your radiator.

Remember, heat rises. The heat problem under the hood of an XJ comes from heat welling up against the hood and not being washed out by the flow of air coming in through the grille, often because you're not moving fast enough to wash it out. If you install hood vents with the louvers pointed away from the air flow so that it's not scooping it into the engine bay, heat will be able to escape upward when you're sitting still, and when moving the air flowing over the louvers will create a negative pressure or suction that will pull air up through them and out of the engine bay, so that cool air can come through the grille with the most efficiency.

As Basslicks said above, a scoop is for putting air into the motor, not into the engine bay around the motor. When you have a functional hood scoop, it will either seal right on top of the air cleaner or have a duct running to the air cleaner that forces cold air directly into the engine's intake. When you see hood scoops that are not connected directly to the engine, those are just for looks and either do nothing at all for performance or actually hurt performance by creating back pressure inside the engine bay.

Originally Posted by MoparNJeep

Just got my hood vents. They are marine vents and very affordable

Originally Posted by JeremyXJ

I just purchased a set of these monsters from Ebay. I don't think anyone has used them on the XJ yet. I'm going to paint mine black and install them soon.

Originally Posted by JeremyXJ

American Rock Rods Universal Hot Rod Rat Rod Hood Louver Panel Set Raw Finish | eBay

$72 for the pair. Not the cheapest, but they're pretty big, high quality pieces. They come with hardware, too. They also offer a powder coated option.

Originally Posted by SteveMongr

Poor mans hood vent, placed between hinge and hood panel. Raises up rear of hood 1/4" at most.