Boeing announced Thursday that order commitments for the upgraded 737 MAX have grown to 600 since the program launched in August with 496 commitments.
Boeing is upgrading the 737 single-aisle commercial airliner with more fuel-efficient engines as it fends off competition from Airbus' A320 neo.
"We're getting strong demand from the marketplace," John Hamilton, Boeing's chief engineer of the 737 program, said Thursday on a conference call with reporters.
After a presentation by Jim Albaugh, head of Boeing's commercial aircraft division, on Thursday, Goldman's aerospace analyst Noah Poponak wrote in a note that "it also sounds like 500 additional MAX orders could be added before 2011 year-end."
Airbus announced its A320neo, a single-aisle plane with new engines, last December. It has more than 1,000 orders and commitments for the plane, which is set to enter service in 2015, two years before the 737 MAX.
Boeing's decision to replace the engines on the popular 737 and extend the life of the program is good news for Spirit AeroSystems in Wichita.
Spirit is a key partner on the program, supplying the 737 fuselage, wing components, pylons and thrust reversers, said Spirit CEO Jeff Turner.
"All those things we anticipate will play substantially the same role on this derivative," he said Thursday.
Spirit has said it derives half of its revenue from the 737.
The 737 MAX is on schedule for service in 2017, Hamilton said, although the team is working to shorten that time period.
Boeing is increasing production of its current 737 Next Generation airliners to 42 per month by 2013 and will consider whether to take production even higher, Albaugh said.
Boeing also announced Thursday that it has chosen a 68-inch fan diameter for CFM International's LEAP 1-B engine on the 737 MAX, up from a 61-inch fan in the current model.
The fan's diameter is important, Hamilton said, because that's the size that will provide the best fuel burn and lowest operating costs on the airplane.
"We've been working with CFM for quite a while in setting a different fan size," Hamilton said.
Boeing said the new engine will have a 10 to 12 percent lower fuel burn than the current 737s and will leap the Airbus A320 neo with a 7 percent operating advantage.
Changing the engines on the 737 will require some changes to the plane's design, although Boeing wants to limit the amount, Hamilton said.
Boeing will lengthen the nose gear to accommodate the new engines, reshape the tail cone to reduce drag and switch to fly-by-wire spoilers to improve production flow and the plane's stopping performance.
Boeing also will strengthen the wing and parts of the fuselage and replace the strut to support the weight of a bigger engine.