With the port exhaust riser joints and showerhead end plate and and spray nozzles welded up, next I repeated the process on the starboard side. I also cut, fitted, and welded the showerhead. These are coming together pretty well.
I’ve seen videos of guys welding exhaust tubing who use devices to rotate the parts at the perfect speed, so all the welder has to do is keep the arc steady and keep feeding in the filler. With no fancy rotator device and all of these tight curves, I’ll get by as best I can by purging the pipe with argon, then stitch welding around each tube. The flange that attaches to the turbo and the showerhead end plate were very challenging because they’re so close to the tight radius mandrel bends. The Series 17 torch that came with my AlphaTIG isn’t huge, but I had to use some less-than-optimal torch angles to get in those tighter spaces.
Raw water will enter the showerhead at the top, so the full length of the exhaust tubing inside the showerhead will be doused with water even at idle. As RPMs rise, more water will flow into the showerhead until it’s completely full and water is spraying out of all of the showerhead nozzles. The overflow tube is at the top of the showerhead, so once pressure starts building the excess water will flow up the overflow tube and off the boat via a hose to a thru-hull. This allows more water to flow through the heat exchangers without the additional water taking up space in the exhaust system. This is potentially an issue since I’m using 6″ exhaust rather than the optimal 8″.
I used clamps to hold sheet aluminum as caps on each end of the showerhead tube, then taped the argon purge line in the water inlet. Argon is heavier than air, so as it fills the cylinder it pushes the air up and out, leaving a nice argon atmosphere to protect the back side of the welded area from sugaring (rapid oxidation and breakdown of the stainless alloy).
Jody over at weldingtipsandtricks.com would probably say that looks like Fido’s butt, but then he’s a pro whose got that wicked robot welding hand that I never will. Camera flash makes a couple of the starts look like there are gaps in the weld, but it’s continuous and well fused all the way around.
After tacking the showerhead in a few spots, I taped up all of the nozzle holes on the bottom to keep the argon from draining out.
My TIG torch travel speed is inconsistent and frequently too slow, which puts too much heat into the part. I’m also inconsistent when it comes to adding filler, so I don’t get that stack o’ dimes look that professional welders can do. But the welds are robust, and I am getting better at making them look nice as time goes on. I was joking with the missus that by the time I finish this project, I’ll have developed these news skills pretty well…but will hopefully never have to use them again. 😉
My original plan was to use two layers of Inferno Wrap, then top that with strips of fiberglass cloth I’ve got left over from the Bullet-proof Cabin Top. Then I was going to use hi-temp epoxy to wet out the top layer and make a hard shell. But I’ve been looking into other approaches and found ceramic insulation blanket material that might be even better. Stay tuned.