Originally Posted by
Grunff
This is one of the reasons 737 could not be equipped with P&W GTF engine. The base design (wing-ground clearance) is from the 60's. It worked fine for turbojets, needed squashed nacelles for larger turbofan but GTF is just step too far. You can only stretch the design so much...
The diameter of the GTF is not necessarily the (only) reason: the LEAP isn't really significantly smaller. Both are very-high bypass turbofan engines, they just achieve the low fan rpm by different means: The PW1000G uses a reduction gear, and the LEAP uses a low-pressure turbine with more stages, which then can turn slower without losing too much efficiency. Just as with the CFM56, compared to the A320 (which was initially designed for high-bypass turbofans), the 737 uses a variant with a reduced fan diameter (and fewer LP turbine stages), but there is no obvious reason why that couldn't have been done with the P&W GTF as well.
Having had a long relationship with CFM International, and having always being a single-source engine aircraft, it seemed straightforward to stay with CFM and use only a single engine type.
The A320 has always been offered with engines from different manufacturers, and they continued that for the neo.
By the way, even the first versions of the 737 had turbofan engines, albeit low-bypass turbofans (P&W JT8D).
Bernd