Air Horn (not the kind you blow)

The past couple of days I fixed something that was bugging me on my XJ conversion. I originally made the air intake consisting of the air box, filter and air horn for the first radiator I had in it which would not keep it cool. I got a Griffin which was about an inch thicker and then added some Derale fans to my shroud and had to space the intake up with nuts under the screws and then had to pound a big dent into it. Anyway it was not up to my usual standards. So I remade it. Here is the old one, you can see the dent I put in it and it was still touching the fan. You can also see the second set of holes to move it back.

http://i649.photobucket.com/albums/u...n/IMG_0471.jpg

This same technique and process can be used to build a classy snorkel or custom air for a 4.0L out of metal instead of PVC and is of course much more durable.

So I started with three inch mandrel exhaust bends. These are the ones I had left over from when I made my 3' exhaust. They have a true 3" radius throughout the bend and are the same technology used by K&N and others to make their air horns for their custom intakes.

http://i649.photobucket.com/albums/u...n/IMG_0470.jpg

I cut another mounting plate and started with what was half a bend and tacked it in. Then I put the air box in position and cut the 180* bend and tacked it into position.

http://i649.photobucket.com/albums/u...n/IMG_0472.jpg

Here it is partially welded. Then I cut a short piece to connect the air box.

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Then it was time to weld it all together. Easier said than done. Exhaust tubing is kind of thin on the long side of those bends. It is also aluminized which affects the shield gas. Many times the welds turn black instead of shiny like most MIG welds. It is necessary to get them aligned as perfectly as possible. To do this I used a bench model belt sander.

http://i649.photobucket.com/albums/u...n/IMG_0479.jpg

Once tacked together I put it all in the vise and proceeded to weld. The method welding two thin edges together is a little different than just regular MIG welding. Normally, you want to weld on the level if you can and set the machine for the proper penetration. But with this, I set the machine to weld 1/8" steel and then welded down hill. MIG welds do not like gravity and will start flowing down hill. I used the puddle to shield the edges of the metal and then still add a good amount of wire. The result is not real pretty, but keeps the edges from disappearing. This is not structural anyway.

http://i649.photobucket.com/albums/u...n/IMG_0474.jpg

I had one spot with a crack in it and was too lazy to cut another, so I used the down hill trick again and stitched it. The nice thing about a MIG is that you can instantly turn it off and on and you don't have to go through the "striking an arc" procedure you do with stick. To weld the crack, I stitched one side down hill from the previous weld, then the other. Let the glow go out of the metal and then down hill stitch the two together, then repeated the process exactly like that. The result looked somewhat like a stick weld that had been done with little circles with the stick.

http://i649.photobucket.com/albums/u...n/IMG_0480.jpg

Next thing to do for a nice effect was grind the welds. I used a typical 4" angle grinder to start and then finished them with an angle die grinder with a sanding disk on it which makes it almost like a mirror.

http://i649.photobucket.com/albums/u...n/IMG_0475.jpg

One last thing was the oil breather tube. I used 1/2" EMT tubing and bent it with a bender.

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Then welded it on.

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I put the AEM filter in the air box and put it all in after painting.

The end result. It fit like it used to.

http://i649.photobucket.com/albums/u...n/IMG_0484.jpg

looks good :thumbsup: now show us the fresh air part of the air filter i see the rubber on that box :cool:

The air box is not part of this build, but I built it. I made it on my brake and shear which the average guy will never own. The sides look like nothing exciting but the bottom is complex to fit the fender well of the XJ. The filter is an AEM, more efficient than a K&N and is a dry filter that is washable, so no fouling of sensors. The rubber is somewhat crude and could have been done better using the hood seal out of a Chevy pickup at the pick and pull. It has push in tabs in it so you just drill holes and push it in to stay there.

http://i649.photobucket.com/albums/u...n/IMG_0490.jpg

The air entrance is through the fender to the box and is not completed yet. One reason is that I have not decided whether or not to build a snorkel. But it will utilize this 3" oval tubing which is the equivalent of 4" round tubing to accommodate the all the horsepower the little V6 will get eventually.

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