Me and some buddies were talking about boosted applications last night over dinner and I brought up the question, "Why doesn't anyone with the LS stuff use the twin scroll setups"?

I know a lot of the smaller cube e.g. 4cyl,6cyl guys use the twin scroll setups on their boost applications. Just curious as to why most of us V8 guys never use them.


And... GO

 

I run a twin scroll... Wilde Racing built his old truck with each bank of cylinders independently feeding each scroll of his S475. I believe he had really good results with it.

 

What's the advantages/disadvantages of running them?!

Had a buddy with a 800hp civic and his twin scroll setup ran dual wastegates... I know civic vs. LS is apples to oranges. I was JW

I see most of the LS guys run a single 38mm+ wastegate. I guess the obvious for running dual wastegates would be to better control boost?!

 

I run a twin scroll on a traditional T4 flange. The manifold has to be designed with this in mind to see any benefit over a traditional single scroll. I think the reason they are used so much in the import scene is because its so easy to build a manifold to dedicate two exhaust ports to each scroll, keeping the volume/length of primaries for each scroll very close to those of the other scroll. I would think this could prevent some issues with turbulence in exhaust flow at the flange on a 4 banger as well, which might be another explanation for the popularity. You wouldn't have that issue on front mount style setups like ran on our trucks. I wouldn't think there would be any benefit to running this style flange on our trucks if you didn't go with a custom build, keeping in mind again equality in the volume/distance of hot piping for each bank.

As for the wastegates, duals aren't needed unless your having issues with boost creep. I'm sure he was just dedicating each wastegate to the two primaries feeding each scroll of his turbo. With a twin scroll designed manifold, he wouldn't be able to use one gate very easily because he couldn't just add it below the flange, without doing some hacking which would either defeat the purpose of the twin scroll design, or cause the gate to be rather inefficient. If it wasn't for the twin scroll setup, I would think he could have possibly gotten by with a single 44mm gate because the close proximity of the gate to the flange will allow it to be very efficient, but a single 50mm would definitely have worked. For the majority of the turbo setups on this site, a 38mm is plenty though.