Quote:
Originally Posted by N0SL3N
I was also going to mention that the BMW went from a twin turbo N54 to a twin scroll N55, although some say the N54 made more power.
Also, the advantage of a twin scroll has to do with the order of firing pulses. Because the Z uses 1-6 firing order on alternate banks and Sasha made sure to keep each header equal length, the pulses will enter the split turbine housing alternately which adds to the efficiency.
I'm sure Sasha can chime in here with more info.
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That essentially sums it up. Each exhaust pulse is able to travel independently through it's own bank/runner. Because of this, one exhaust pulse will scavenge the exhaust out of the following combustion chamber once the exhaust valve opens...allowing more air to enter it on the next compression cycle. More air in = more power. There is simply no exhaust interference between exhaust pulses, allowing for a very efficient flowing system.