Images of the components
I finished my 3" exhaust and thought I was a bad welder until I saw the above (rolls eyes) here are some shots of the turbo-back components. Let me say that 3" is the biggest you are going to sneak into a libery CRD without pulling the ****** cross member and doing some serious fabrication. Could it be done, yes. Should it be, no. This follows the rule of diminishing returns. While I have forgotten most of my fluid dynamics, going from stock to 3" is a massive increase in capacity... not to mention the deletion of certain other items
This exhaust was fabricated out of DOM 3" OD 0.065 wall 304L and the bends where 304L 3" OD 0.065 welded seem (hate welded seem, it's gutter shit and the welds fail, even on a mandrel bender). The joints where welded using an inverter rig set to 109 Amps, DCEN, and pedal control (I only used full power to weld the flanges). Used 2% ceriated tungstens 1/16" with a small cup and lense at 8GPH straight argon. The filler was 316 1/16" or 0.040 wire at times. Probably did the butt-jointed pipes and bends at 70-90 amps. The flanges where heat-vampires and I used 3/32" 316 filler and full power. Important to have AT LEAST 10 seconds of post flow (I used 14) and back gas for a couple of minutes a 1GPH (if you are welding up SS).
The challenge was trying to avoid "heat treating" v. "welding". Finally got the hang of pipe welding and would mash the pedal down and get moving. Sometimes the weld puddle wouldn't "wet out" on both sides of the butt joint due to heat absorption, so I would use a lighter peddle, move the tungsten closer and weave back and forth across the butt-jointed pipes, while dabbing small-diameter filler. This ensured that I was dragging the wet puddle all the way across the joint. Would constantly dab filler rod into the puddle to build it up a little. If you don't understand what I am saying, do some experimenting and it will become immediately apparent.
One thing that stumped me was "sectioning" the entire exhaust, such that I could assemble/disassemble the exhaust without lowering the ****** t-member. Removal of the stocker was a snap with a plasma cutter (could have used a stumpy blade on a sawsall, for the same effect). I decided to put a flange joint smack dab in the middle of the cross member. While this is a PITA to assemble and disassemble, it made it possible to create three distinct sections that can be removed with minimal disassembly of other parts. The first section is from the turbo to the flange (the flange meets it's next section in the middle of the cross member just behind the exhaust support) and includes an 8" flex section (see pictures). The second section is an angled straight pipe, through the muffler, and up toward the top of the wheel well which terminates at the second (and last) flange. The third section continues from the second flange and bends over the axle and kicks out to meet the OEM tailpipe position.
The process was a repetitive "tack, fit, check, adjust, tack, fit check" cycle that started at the turbo flange and worked all the way back from that flange.
I have a local shop approximate the turbo down-pipe and had to carve it up and adjust for clearances etc. If I had it to do over, I would bought a kit full of bends (not welded seam pipe) for like $400 and customed-up the whole thing. The only way to net-out on buying bends would be to put your rig up on someones rack and have them bend up every piece for you.... and they will want double the money to do it.
Feel free to axe questions. I will share my success (and failures) with you as honestly as possible.
-Marc