January 09, 2013

Wastegate, Take 3 (Now With Dump Tube)

After a several month hiatus, I am back with some visible progress. After awhile of picking at projects, I found myself road blocked by welding which I (admittedly) put off for several weeks.

Backing up a bit, in October I had sent out/received my TiAL F38 from a "rebuild". I had had the original wastegate housing powder coated a second time in March, only to experience adhesion issues (chipping) during reassembly. Frustrated, I settled on replacing the housing with one of TiAL's black anodized pieces. This required sending the whole unit in to ensure I wasn't trying to assemble a knock-off. Much to my surprise, the wastegate returned with my damaged housing. Now I have the convenience of a spare should I attempt to powder coat again. One more disassembly was required to clock the housing so the side port was in the right position - hopefully I don't have to take this thing back apart for awhile. Onto the dump tube.

Leave it to me to let a simple item get out of hand. I knew initially that I wanted something a little more elegant than a straight tube pointed at the ground.  After playing around with some 1.5" bends I decided I would create something that followed the contours of my downpipe. Chasing symmetry resulted in the dump tube wrapping under the downpipe and following its line over the front sway bar, necessitating the extra bend a short ways before the outlet.

The flange and first two bends had actually been tacked together earlier in the year to provide me with something sturdy to mock up the rest of the tubing to. After letting it sit marked, taped together, and ready for several months, I finally brought it back to Scott at Ballistic for final TIG welding (along with several other items). His work exceeded my expectations again with amazingly consistent beads, despite the fit up of my pieces not being 100%.

Final fitment of the dump tube is really tight in one spot near the downpipe, but clears everything (this is starting to become a recurring trend with this build). Part of my tolerance issue is from routing the bends so close to the downpipe while not giving myself of large enough margin of error. Tape is only so structurally sound so I probably overlooked some settling between dry fitting and welding. It will probably get tweaked in the future, but for now I am more focussed on getting the car in one piece. Expect a few teasers of other projects in the coming weeks!

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