Twin Scroll Turbo

[KoogiA17]

Let's see a picture of your model. Since it is a model save as a .stl file and have it printed in abs or ultem and test fit it. Ultem you might be able to run it for 30 seconds b

It would be the same as the last pic but now everything lines up.


Not a bad idea to have it 3d printed. Could do it all in one if someone in the UK has a big enough printer (we are a bit Stoneage when it comes to cost effective 3d printing services), otherwise print it in sections. Having said that, am tempted to measure up the engine bay, block, mounts etc and model them in CAD. Only stumbling block is that I basically dismantled the engine bay chasing the dreaded tin worm. If there was a spot weld in the bay then it got drilled out.

[squaab99t]

Let's see a picture of your model. Since it is a model save as a .stl file and have it printed in abs or ultem and test fit it. Ultem you might be able to run it for 30 seconds b

It would be the same as the last pic but now everything lines up.


Not a bad idea to have it 3d printed. Could do it all in one if someone in the UK has a big enough printer (we are a bit Stoneage when it comes to cost effective 3d printing services), otherwise print it in sections. Having said that, am tempted to measure up the engine bay, block, mounts etc and model them in CAD. Only stumbling block is that I basically dismantled the engine bay chasing the dreaded tin worm. If there was a spot weld in the bay then it got drilled out.

That is very tighty if you can maintain the CRLs you need.


Print the runners in smaller sections and reassemble with bonding agent is the way to go. I would model in index features such as witness marks or even a tab and slot to the respective ends of the sections to get the clocking correct.

[squaab99t]

Primaries 2 and 3 are fully welded. Reassembled with the merge collector and the turbo attached. Everything seems to line up and I can leave Swedish wrench in the tool box.

Next phase is the external wastegates. My initial design, I'm going to have to hack into the Burns merge collectors for the bleed off tubes. Got to break some eggs to bake a cake.

[squaab99t]

The wastegate V band inlet and outlet flanges are 1 7/8" and 1 3/4" respectively. I have a box full of 1 5/8" drops that came from all the U bends I used for the primaries. So how does one make use of those? A press, repurposing a flare die, and some assy lube
My friend Kevin helped me crank out these gems:

He used his lathe to turn down the OD to mate to the flange. One could also use a belt sander to dial in the OD.

That is the sex. Don't even want to cover that up with a weld.

[squaab99t]

Wonder how far the engine will move in operation?

Would probably start with more bend off the head / straight section rather than going to a tighter radius. Could ovalise some of the tubing /fabricate an ovalised tubing in the affected area maintaining CSA but probably more of a challenge to get right. Might not give enough clearance anway.

Went with the local ovalized area. Backed up the tubing with some scrap 1/2" UHMW (plastic) and used a hand clamp to massage the area. I have enough space now to add a thermal barrier to protect the bushing.

[squaab99t]

Progress on the wastegates. Working on the 2-3 runners. At first I could just come off of the lower and life would be simple. Thought about it and decided against the idea.
So the wastegate bleed tube should be 90* or less to the flow. The shallow the better according to Turbosmart.
Mocked up in situ.

All well in good except there is a gap at the crotch of the Y on the merge collector. Plan is to add a little wedge of sheet and that will close off the backside. I'll drill two holes/ellipses in the merge collector or a larger single shape.

[squaab99t]

I pulled the trigger on finalizing the wastegate branch off the merge collector.
Welded in the web to close out the gap left by the ellipse.

Had to cowboyup on this move. With a step drill bit I added the holes, and it was not happy about it. Raining hot chips of metal and cutting fluid on to my ankles it let me know about it. Shorts in the shop has it pluses and minuses.

Tack and welded

Inside the two ellipses make up 70% of the cross sectional area of the wastegate. This should be plenty, as single wastegate is sized for all four of the primaries.

Now off to do the other side 1 and 4 primaries

[Nate]

Phenomenal work as always!

What size wastegates are you going to use? Looks like 2" piping.

What is your next project going to be? Some sort of crazy compound turbo setup?

[squaab99t]

Phenomenal work as always!

What size wastegates are you going to use? Looks like 2" piping.

What is your next project going to be? Some sort of crazy compound turbo setup?

Thanks for the complement.
I'm using the leftover 1 5/8 tubing from the U bends used on the primaries. It is about .063" wall, so that makes the inner diameter 1 1/2".
I flared out the tubing to match the supplied wastegate V band fittings.

Wastegate I sized will be a bit of experiment. I originally had a 45mm I was going to use on another project. I repurposed that to be on primaries 2 and 3 which are the long runners. ~30" and 32", respectively. So, I had to buy another wastegate due to the twin scroll. 1 and 4 will be a 40mm wastegate. These have the short runners ~26" and 27", respectively. The smaller size saves a few bucks and volume in the engine compartment.

I have not tacked the fittings/tubes to the banks yet. The wastegates and fittings are different sizes, so you can't swap the units side to side. Need to sit down and plan the strategy of the two sizes. I may have to swap 180 degrees to what I wrote above?

I ran a single TiAl 38mm thru the turbo swing gate hole in the turbine housing using this turbo compressor. The two gate setup will be more than enough to control the boost. At least that is what I'm telling myself.

Next project might be a while. Kinda blew my mojo on this one. Coming up on 9 months since I decommissioned the old downpipe and exhaust manifold.

Might be tough to top this one, as this one has taken on a life of its own. I'm sure I'll think of something.

[DrewP]

I haven't even gotten around to making a set of those socket weld pipe fitting bookends that Jody posted about... I think you're doing pretty great.

The twin wastegates are going to look pretty rad stuffed down in there! I've gotta get a video of my car with the short headers and Simons exhaust. Without the log manifold the exhaust note is very non-C900.

[squaab99t]

I haven't even gotten around to making a set of those socket weld pipe fitting bookends that Jody posted about... I think you're doing pretty great.

The twin wastegates are going to look pretty rad stuffed down in there! I've gotta get a video of my car with the short headers and Simons exhaust. Without the log manifold the exhaust note is very non-C900.

Life does get in the way of some of those optional projects.
Dual wastegate is going to look bad ass. Maybe some scream pipes out the top of the hood?
I have been joneszin to fire it up to hear the tone. Still need new oil and water lines to the turbo, but in reality that is the easy stuff.
Main thing is that I want to work on it at a pace that is fun/learning and not work/chore to get it done.

[squaab99t]

Working the left side wastegate. Went much quicker than the first, so I thought. Fit up was good and got a good handle on how much and where to remove material with the belt grinder.

Time to check fit up in the car. Should have all sorts of room without the downpipe, turbine or fender.

Crashes into the compressor outlet. Doh!
This is why I use the blue tape. Measure twice, weld once in this case.
Need to reclock the wastegate pipe a few degrees and it should clear the housing outlet.

[Jordan]

Hey Dennis,

I followed all of your instructions but my header doesn't look the same, what gives?

[Crazyswede]

I think its just a photography lighting problem

[squaab99t]

I think its just a photography lighting problem

I agree, it should look a bit better as the sun goes down, or you slam the hood closed.