Definitive LEAP1-B fan diameter!(?)

Yesterday at the ISTAT Americas conference Mike Bair from Boeing revealed that the LEAP-1B fan diameter for the B737MAX now stands at 68.4". When Boeing and CFM for the first time officially announced a fan diameter for the LEAP1-B in November 2011 (Press Release), it was 68", 7" more than the fan diameter of the CFM56-7BE of the current B737NG.
In the meantime there were news in different but reliable media (LeehamNews, aspire aviation) that the diameter went up to 68 3/4" or 68.5". So now it is 68.4" - what does that tell us?

1. Size matters - although Boeing denies that. Well, of course there is a sweet spot for every aircraft/engine combination, as Scott Hamilton writes in a recent column, so you can't go everywhere with fan size. But apparently CFM still tries to maximize the fan diameter of the LEAP-1B so it just fits under the wing and to get the best possible fuel burn for the aircraft. That means that 68" is not the sweet spot, but that is is somewhere higher.
2. It means that the definition of the engine is probably still not finished yet. If the fan size changes, this potentially changes everything else - at least if you want to maximize efficiency of the whole engine. In turn that means that there is still a lot work for Boeing to define to pylon and the pylon/wing interface.

So stay tuned for the next MAX fan diameter...

Ryanair and B737MAX

Not often I tend to agree with the outspoken Ryanair CEO Michael O´Leary, nicknamed by the twitter community with @MichaelOhReally. But when he recently talked about the B737 MAX, I had to agree with him. He said that he has been impressed by the fuel burn improvement the A320neo promises to deliver, but he is not impressed by the B737 MAX and said that the fuel born improvement is inferior.
Particularly he fears that the heavier CFM LEAP-1B engines and the subsequent heavier airframe will offset the better SFC, when compared to the CFM56-7B(E).
Meanwhile I had the opportunity to read the latest

News about MAX

Jon Ostrower (Flightblogger)  and Scott Hamilton both are reporting about a presentation given by Boeing Commercial Airplanes CEO Jim Albaugh at Goldman Sachs.

B737RE Early Fuel Burn Analysis

Scott Hamilton picked up a few interesting details from the Boeing Quarterly Earnings Call regarding the B737RE. The most important question regarding this program remains the fan diameter. It looks like it will settle around 66 inches, so that Boeing can go forward without touching the nose gear.
But what does that mean for fuel efficiency?

B737RE Fan Diameter

The efficiency (SFC) of the LEAP engine for the B737RE (I call it the LEAP-2B as I think it needs a different, aka smaller core) very much depends on the fan diameter, as with a larger fan you can have a higher bypass ratio, enabling a smaller Fan Pressure Ratio (FPR), which translates in a higher propulsive efficiency.
For now there are four fan sizes in discussion, reportedly ranging from 63" to 70". The lower end represents