Maybe for most this is self explanatory. But, obviously I am way dumb. In a twinscroll setup, such as the factory Evo setup, if your gonna do external wastegate(s), then dual external wastegates are required.

If, hypothetically, I had a non-gated 16G TS housing and I wanted to gate it externally on the manifold, I would need to plumb dual external gates. That is, with a TS 16G manifold there is no way that one single external gate can be made to work.

Am I dumb or what? Will somebody please shed some light?

 

No. Twin scroll does not require two gates.

With one gate, the exhaust flow paths simply have to be divided all the way up to the gate.

 

For a true twin scroll you do need twin gates. Having said that you can merge both sides into one gate like a "Y'. Right now the external wastegate housing I am using has it split. I have thought the same thing about this and I think that is why Buschur didn't get great results when he welded on one wastegate to one runner on the manifold. I would test both to see. I am using a 38mm tial. Try a single, then one wastegate merged from both sides, then two separate wastegates.

Here is a pic of mine.

 

... meaning that a true twin scroll does NOT need twin gates.

Not to keep harping on this, but the notion that "two gates are required" is a myth that needs to die.

 

From what the top fabricators say is that in order for a true twin scroll you need two gates. I have not tested this myself but this is what they do. `Have you tested this or guessing?

 

DTM's TS kits use one gate. Their results have been positive thus far. Not sure how this could not be considered a true TS...

 

DTM uses a DNP manifold. The twin gates allow for quicker spool. This is the point of a twin scroll and also gives more consistent flow to the wastegate. Don't quote me on that though. Hopefully some of our fabricators will come chime in on this.

 

So long as one side of the manifold cannot cause a pressure fluctuation inside the other, one WG will work. The only way to do this is to engineer a divider that keeps both sides completely divided right up to the WG valve orifice. When the WG is opened, the pressure on the outside is lower than either side of the manifold, which should prevent one side of the manifold from pressurizing the other.

In the photo RevMoto posted, the divider stops short of the WG valve, so theoretically, one side is more likely to pressurize the other while the WG is closed.

 

This man is smart. Listen to what he says.

He has professional experience with turbos.

 

The wastegate has a ring that sits in that spot. Can't get the divider any further out. I know the DNP manifold doesn't have one.

 

Im lost was that supposed to be taken sarcastically or seriously ?

 

Then that particular WG design doesn't appear to be well suited toward a single WG, TS application. There is nothing to prevent exhaust pressure from zipping right around the edge of the divider.

With a TiAl 44mm, the divider can be machined flush with the WG valve. I don't know about other WGs, as I never considered them for this application.

 

I will let you know how it works.

 

Well that's just it, because I don't think you would necessarily recognize it if it didn't work properly. What would probably happen is some pressure from one side would be reduced on its way to the turbine. Essentially, that would negate some of the TS benefit. As to how much or how little, no one can say for certain.

 

For the distance I cannot imagine it being too much. I might have to extend it 3-4 inches do to fitment issues. How much do you think that will effect it?