Originally Posted by
tdracer
The GEnx is shared between the 787 and the 747-8, but the requirements were enough different that the engines are far from identical. Relative to the -1B on the 787, the GEnx-2B on the 747 has a ~7 inch smaller fan, the low compressor (booster in GE lingo) is completely different with one less stage, the LP turbine is completely different, and the gearbox is completely different (to accommodate an IDG instead of the two big starter/generators on the 787) . Only the HP core is common. GE spent a boatload (well into 9 figures) developing the -2B from the -1B.
Indeed. And that was for a relatively "minor" installation change that did not involve the core. To obtain the improvements Emirates wants and Airbus promised would require far more changes and more importantly, very significant (and very very expensive) changes to the core. And significant risk. There is no certainty that applying the technologies developed for later engines would work on the Trent 900. GE, Pratt and Rolls have all been bitten when they tried to back fit new technology into older engines. Making such an investment and taking on such risk for 36 shipsets of engines is simply untenable.