It appears you paired 1&3 and 2&4, that correct?



I'm going to let that soak in...

I was excited about this and was just going to watch, then it started going downhill.

Then I realized you're only going to use one wastegate, was really hoping for a proper twin scroll system but whatever.

Then on your last post I see you built the manifold completely wrong and you paired the incorrect cylinders, and that's where I stopped reading...

[ scrollscroll | scrollscroll ]

obvious answer is obvious. Custom crank and cams.

oh boy

I was so excited....now I'm sad :cry:

This NOW applies!

:party:

Now I kind of want to see him finish this. I wonder how it will perform. Dont think it's been done this way before. Bets on if it's worse or equal to single scroll?

The only way to know would be to build the same exact manifold with a 4-1 merge and the same turbine A/R but in a single scroll on the same turbo, which won't happen. This turbo will spin, it will make boost: he will win because X.

Couldnt you take this manifold. And grind out the divider?

Yeah, duh. Or just a single scroll turbine housing with the same flange.

:rofl: even more duh.

I know nothing about twin scroll. Once again MT.net learns me. My education is ongoing.

The point of it is to separate exhaust pulses. So they don't run into each other/into other open exhaust valves. So you want 1&4 paired and 2&3 paired. Firing order is 1-3-4-2. So it fires into opposite scrolls each ignition event.

Makes total sense. I guess if I thought about it for ten three minutes, I would have drawn a similar conclusion. Isn't this like, exactly the same as a 4-2-1 header? Keeping gas pulses moving foreward and pulling the next one behind.

1-4 and 2-3 should be tied together.

Will this need a brace? I don't remember but you said you where doing a stepped runner, is that just where the two converge to one per port on the flange?

Edit: had the respond window open too long. My post is now irrelevant

I know nothing about manifold design... but I do remember something about 4-2-1 headers. Is there any substantial performance disadvantage to merging the 1&4, 2&3 BEFORE the turbo flange? Is the flow path too short at this point to make merging practical? I would imagine that it might make packaging easier. Am I mistaken?

Yes you're mistaken. You have it backwards, there is a performance advantage when pairing 1/4 and 2/3 before the turbine housing, not a disadvantage. And yes it matters, it's the entire basis of how twin scroll works.

I think he is asking why not have the runners connect at the flange instead of inches before.

If that's the question then I don't think that would have a noticeable effect with only a couple inches difference.