The modern 777-200ER is a 7700nm frame at spec load of 29t and has a 288m2 cabin in my book. MSP at the 10 hour flight is 57t.
I checked what different measures on the 330 series would give in extra range using my frame model:
A333, a 6000nm frame at a spec load of 28t and 266m2 cabin, MSP 51t:
- raise MTOW from 235 to 240t (with no significant increase in OEW) = + 350nm
- change to sharklets (with no significant increase in OEW) = + 70nm
- PIP the engines 1.5% = + 100nm
Spec range goes from 6000nm to some 6500nm.
A332, a 7200nm frame at a spec load of 24t and 238m2 cabin,. MSP 48t:
- raise MTOW from 238 to 240t (with no significant increase in OEW) = + 140nm
- change to sharklets (with no significant increase in OEW) = + 80nm
- PIP the engines 1.5% = + 110nm
Spec range goes from 7250nm to some 7600nm.
As can be seen an extra hour or 500nm is within the possible without larger measures. The 332 would run the legs of the 777-200ER albeit with some 5t less on the max range and some 9t less on 10h flights, it lacks 50m2 of cabin area to the 200ER. The 333 runs 1200nm shorter, lacks some 6t payload weight on those distances as well at MZFW, it also lacks 20m2 cabin area to the 200ER. Fuel burn would be some 10t lower on the 6500nm legs for the 333. As always add a grain of salt
So why these differences, well the -200ER is a bigger frame, it weighs some 10-15t more empty and it creates more drag when cruising, some 26000lbf instead of 21000lbf for the 330.
[Edited 2012-07-04 13:26:41]