[ORIGIN M.]

Bingo!

Originally Posted by atr_hugo

Let's give it a stab - The four cylinder crank is a single plane crank with cylinders 2 & 3 throw's being 180 degrees out of cylinders 1 & 4 throw's.

Firing Sequence is generally either 1-3-4-2 or 1-2-4-3. If it's the later then a small turbo is coupled to 1 &2 and another to 4 & 3.

Output from those two turbos would provide boost quickly at low load/RPM. A third larger turbo (fed from the output of the two smaller turbos or fed by bypassing the two smaller turbos) would handle the higher RPM boost requirements. That's just my guess.

However, if this is to be a high RPM motor (say 8K + RPM) then it probably won't be direct injected. And some fans of the HPFP are giving a sigh of relief with that factoid. ; -)