Quote:
Originally Posted by Allerum
Cylinders 1 and 5 feeding one scroll and Cylinder 3 feeding one for turbo 1
Cylinders 6 and 2 Feeding one and Cylinder 4 feeding the other fir turbo 2.
Now is this ideal? No would it work yes, there is only one exhaust wheel just two passages to the vanes.
I wish BMW did a manifold with 1,5,3 and 6,2,4 for mono scrolls as that would be an even sounding exhaust.
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Twin Scroll requires consistent evenly dispersed pulses into each scroll every 360° of crank rotation - to enjoy the benefits of twin scroll. Not only are you not achieving consistent pulses into each scroll throughout the fire order, you have the other turbo hanging out doing nothing for half the crank cycle. this will create non-uniform pressure.
your example above - Turbo one would have two pulses on one scroll cyl 1 fire and then Cyl 5... so far turbo 2 hasn't received anything 120° into rotation - being pushed against from the boost side to boot. and then the other scroll of turbo 1 gets one more pulse - we are now 180° crank rotation - and still have turbo 2 dead weight, then you are merely reversing this for the last 180° rotation.
anyway...
would this work? well... there are many ways to make boost, but this by far inferior. The entire reason for twin scroll is to deliver more power from less fuel than a single counterpart by providing consistent pulses throughout the crank rotation. your example there are huge gaps in the crank rotation would provide less power, more fuel and horrible response. (opposite desired effect).
two twin scroll turbos needs 8 cyls. end of story. no manufacturer or performance shop
uses severely handicapped setups like two twin scroll turbos run by 6 cylinders for a reason.