Quote:
Originally Posted by SlowSaloonM3
bigger turbos have more lag. two smaller ones would have better response right?
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Usually, yes, it takes less exhaust to spool them up quicker. Downside, is less final boost. That is why they use two small ones on N54.
Also, someone asked where did I get that. Car and Driver tested N54 and N55 side by side and they found quicker throttle response. My butt meter confirms it. I jumped from my 2011 1M to friend's 2011 335i and throttle response quicker. I think CD article was around 2010. The single turbo uses two exhaust scrolls instead of 1 like older turbo so you have a smaller exhaust pass-through which maintains exhaust velocity. Older turbos had all 4,6,or 8 cylinders feeding a single exhaust scroll. That is why the call the BMW turbos Twin-Turbo. It's a single turbo with twin scrolls power the compression impeller. Great idea.