Twin Scroll Turbo

[schwartz]

Great work! Wish I could weld like that...

[squaab99t]

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Great work! Wish I could weld like that...

Practice and more practice. Also asking other welders for tips.
I reinstalled the whole shooting match back into the car. Time to get the downpipe hooked up to the existing exhaust. I added everything back and tighten.

This seemed to go much easier than the primaries. No length requirement, just line it up and get the ends flush.

After I tacked it one last fit check and fire up the torch.

[squaab99t]

Worked on the intake end. Intercooler plumbing with the new turbo location.
Have not done aluminum in a while, but much nicer than my welds from 8 years ago.
A bit of helmet time since then

Placed in the car. Much shorter than the old arrangement.

[squaab99t]

Was not happy with the way the tube exited the compressor outlet. Added a little extra bend just before the interface. The coupler will only make up for minor misalignment.

Moving on to the water and oil plumbing for the turbo. I'm going to try the aeroquip socket less fittings and hose this round. I'll use fire sleeve in the local area where I think it will be over 300*F
Need to build a new block oil return fitting as the current one gets the too close to the header primary.

[squaab99t]

Working the oil return fitting. Kevin said it is not as glamorous as the header, but just as important and getting it done is progress to the project.
Took the OEM tube, cut a 45* on the bend and a -10 bung.

Welded and fit check.

A base will be added to the fitting. This base picks up the two fasteners(gearbox and block) that flank the port in the block.

[DrewP]

Nice. I really like those push-on fittings, makes the plumbing jobs so much easier.

[squaab99t]

Nice. I really like those push-on fittings, makes the plumbing jobs so much easier.

Have you used them in any high radiant heat areas? Pegasus racing store recommends using a crimp band clamp or two on each fitting. I'll check what the aeroquip site has to say.

[DrewP]

I think we might have used those on the oil and coolant lines for that monstrous turbo LS2'd Z3 that we built. Hose clamps or band clamps definitely won't hurt anything. I'll trade that for getting steel braid strands shoved up under my fingernails from terminating AN lines any day.

[squaab99t]

Nice. I really like those push-on fittings, makes the plumbing jobs so much easier.

They are almost seem too good to be true. Heated the hose with a heat gun, lubed the fitting's barbs with some assembly lube oil and jammed it straight on. Cut the hose with a single edge razor blade. No cutoff wheels and having to clean out debris post cut.

Added silicone fiberglass sheathing for added heat protection.

The shark bite clamps were too small to allow the fitting to be inserted or slip on after the fitting was in place on the -10. I'm suspecting the same on the -6.

[squaab99t]

Clean shot of how the merge collector keepers turner out.
Craig suggested some spring washers to reduce thermal expansion stress cycling the ears. I'm thinking McMaster should have something to fit the bill.

[squaab99t]

A week holiday with the family was wonderful. Now back at it, and ready to finish up this project.
Got the plumbing lines finished. Super easy with the socketless fitting.

Finished the block oil return line

In Situ

Line attached.

[squaab99t]

Need to create a new inlet for the new turbo location.
Cardboard mockup, just like Project Binky.

The turbo inlet is 4" dia and the air filter is 3".
The shape is an attempt to keep the air attached to the inside radius and feed the inlet equally.
I get to try my hand at panel beating. I'm equipped with a teardrop shot mallet and a shot bag. Should be fun.

[squaab99t]

Back to the header. Well at least a road to finishing up the primaries. One of the last steps is TIG welding the flange on the head side and TIG braze a silicone bronze fillet on the visible side of the flange. The idea is that silicone bronze acts as a strain relief gusset. Opposed to a stainless steel TIG fillet which will have a large step in stiffness and likely cause a fracture of the tubing. This brazing is not without issues. We are getting cracks in the braze as it cools. It could be caused by the stresses in the tubing from when it is curved and/or to amount of stretching required to get the tube to mate up inside the flange opening itself.
I made some practice coupons before I attempted the read deal. I made some straight tubes passing thru a 3/8" plate just to work on technique and settings. Once I felt like I had a fighting chance I went for the mockup parts.

Parts prepped for braze:
Fully TIG on the back end

Cleaned up with the burr bit and belt grinder

Nice and tight fit on the front end.

Finished coupons:

This one shows a crack in the radius of the tube, but is crack free in the straight section.

This seems to be the norm on both Kevin's flanges and mine. His are worst as the big block Chevy head port are square with round corners. A round peg wanting to fill the square hole.

[Mezzanine]

Per our message the other day: since the bronze is just acting as a bushing, the cracking doesn't matter...Have you decided to just leave it then?

[squaab99t]

Per our message the other day: since the bronze is just acting as a bushing, the cracking doesn't matter...Have you decided to just leave it then?

We are still gathering data and opinions from folks in the industry. Kevin has been doing some awesome legwork and having conversations with leaders ( engineering and practitioners) in the business. I am going to write a few folks and ask their options.

I'm going to try a few more coupons with some of the suggestion we have gathered. See how they turn out.