Twin scroll vs twin turbo

SS_Firehawk

I've been looking around the world wide Google for the past week looking for information on this topic. All I get is N54 vs N55 BMW BS. I've only gotten bits and pieces on information, and not the whole picture. I'm hoping someone in here can help shed light on this topic. Option for forced induction is expanding on our vehicles, and this is definitely something I think can be expounded upon for the rest of the community who are like me and asking this question.

So as I understand it (very basic), twin scrolls divide the cylinders to different ports on the turbo to prevent backflow. With a 4 or 6 cylinder motor, I can see this working great. With a V8, I think one twin scroll per bank will be the most beneficial. It's most likely the reason why every single turbo V8 that has come to market has come with two twin scroll turbo's, and not one.

Taking this out of context, this may be part of the reason BMW moved from TT's to single scroll. They made similar power and more torque at lower rpm's. Could it be because the exhaust is only powering one turbine as opposed to two? It seems like the right size turbo for the job is crucial regardless. So what are the benefits of a TT system (on our vehicle) over a twin scroll if the primary reason people went TT was to reduce the lag from one large single turbo, and the twin scroll seems to have taken care of this? The one big advantage I can see with TT's is getting it closer to motor.

Thanks in advance for the help in understanding.

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