For a TIG job like ours, Lang charges about $350, which doesn't include the parts or the labor to construct our custom double-hump transmission crossmember. Lang and Dr. Gas both say that TIG welding isn't a necessity for this operation, but it's Lang's specialty, and at that price, we decided to go with the flow. It took about six hours to build our Laguna's exhaust system with the parts provided by Dr. Gas. When the labor charges are added to the cost of the Dr. Gas components, our one-of-a-kind side-exit system cost around $1,330. If you need to extract the maximum power potential from your engine, and you like the visual and audio shock value of a side-exit race system, that price isn't out of line. (If it were a piece of high-end sculpture, you'd pay five times the price for it.) Next month, we'll be installing a brand-new, bolt-in steering box from CPP that has transformed Project Talladega's handling, so stay tuned.
Lang TIG welds the transmission...
Lang TIG welds the transmission brace to the crossmember. While most shops prefer to MIG weld because it's easier, Lang prefers TIG because the welds are stronger (if done correctly) and they have a nicer cosmetic appearance. Since Lang does a lot of chassis work that must be certified by sanctioning bodies, he's got a good handle on his weld quality.
With our new double-hump crossmember...
With our new double-hump crossmember fabricated, spray bombed, and installed, Lang can start on the Dr. Gas exhaust system. Note the ample clearance for the dual exhaust. It definitely helped that our Hooker headers were already installed.
Here are the raw materials...
Here are the raw materials we got from Dr. Gas. We used 3-inch aluminized mild-steel oval tubing, which does not have the same cross-sectional area as 3-inch round tubing, but Dr. Gas deemed it to be plenty for our 560hp, 408ci small-block. Note that the photo includes two 60-degree oval tubing bends, which were not needed. Should your project call for them (part No. OB3360) they are $57.95 each.
The first step is to hold...
The first step is to hold the cross-pipe at the centerline of the car with a pole jack. With the collector flanges loosely bolted on, cut the 60-degree transition tubes to fit. You'll need to do this in stages and sneak up on the length. The transition tubes go from 3-inch round, and transition gradually to oval, and can be slipped inside the collector flanges to help hold them in place.
As the various tubes are cut...
As the various tubes are cut to size and adjusted, you'll need to make temporary tack welds to hold them in place. These may occasionally have to be broken and reset as your geometry becomes more clear. Here, Lang uses a MIG welder to tack one of the transition pipes to the X-pipe. Again, this is an iterative process that will need to be fine-tuned.
An electric chopsaw makes...
An electric chopsaw makes easy work of cutting exhaust pipe, and yields clean, straight cuts that make for easier welding. If you don't have one, you can use a cut-off wheel or Sawzall, but you'll need to hold your work steady in a vice while cutting. Here, Lang is making a slight adjustment to the length and angle of the transition tube so that it enters the X pipe at the proper angle.
Once the length of the pipe...
Once the length of the pipe and the angle of the cut are established, and you make the final cut, it's important to properly dress the area of the butt weld. Lang likes to start with a die grinder to remove the cutting flash, then he follows that up with a Scotch-Brite pad. This burnishes the edge, removing smaller burrs, but it also helps clean the weld area of contaminants like rust and machine oil. A third step is to clean the area with acetone before welding to remove any remaining chemicals.
We've got the transition tubes...
We've got the transition tubes and the cross-pipe at the proper length and angles, and everything's been tack welded in place. Now it's time to establish the cross-pipe parallel to the floor as close as we can get it. This needs to be done before we move on to the Boom Tube mufflers. At this stage, Lang is tack welding the transition tubes to the collector flanges with some robust MIG tack welds.
The exhaust exits the cross-pipe...
The exhaust exits the cross-pipe and into the Boom Tube mufflers through a pair of oval expansion tubes. These expansion tubes don't match up perfectly with the Boom Tube mufflers or the cross-pipe, and need to be shaped with a ballpeen hammer at the corners. (They are oval in shape, and basically need to be made more "square.") This will reduce the mount of area that needs to be filled with weld media.
It's sheer folly to describe...
It's sheer folly to describe the art of TIG welding in one photo caption, but suffice it to say that it can be learned surprisingly quickly. Lang says a month or two of practicing can yield pro results if you're willing to put in the practice. Lang likens it to a combination of gas welding (you use a hand-held filler rod, not a machine-fed filler), and arc welding (where the Tungsten electrode acts very much like the stick with arc welding). The operation shown here is the collector weld, for which Lang is using 45 thousandths mild steel ER70S2 filler rod.
Note the multi-colored heat-affected...
Note the multi-colored heat-affected zone that characterizes a TIG weld, as well as the very controlled weld path. This is the mark of an experienced welder when you see this kind of precision. To finish the weld, Lang likes to use a silicon bronze filler on the outside of his exhaust welds to act as a stiffener. This imparts a "gold" sheen at the joint.
With the position of the cross-pipe...
With the position of the cross-pipe firmly established, it's time to locate the Boom Tube mufflers. The best approach is to complete one side, then mimic that placement and angle on the other side. Note that you are really working with two pieces here, the flat expansion tube that transitions between the cross-pipe and the muffler, and the Boom Tube muffler itself.