The wing-tip device will give operators fuel savings of 1.5 percent on top of the 10-12 percent savings the company says it can deliver by putting new engines in the 737. The MAX, due to enter the market in 2017, competes with the Airbus (EAD.PA) A320neo, which will also feature new engines.

The news on Wednesday will stimulate sales of the MAX and encourage customers with provisional orders to convert them to firm orders faster, said Alex Hamilton, an aerospace analyst and managing director of EarlyBirdCapital.

"It's definitely going to help," he said. "It appears they've been getting a lot of orders. They've been taking Airbus' thunder away."

"It's like you're preordering a car, and then they announce that the car is going to be even better," Hamilton said. "It would certainly whet your whistle a little more."

Boeing said it has taken more than 1,000 orders and provisional commitments to buy the plane from 16 customers. Airbus has taken 1,289 firm orders and 266 provisional orders for its competing neo as of end March.

The neo comes to market in 2015 and promises to deliver 15 percent greater fuel efficiency than the current A320, including savings generated by its version of the winglet.

A winglet is a feature used on the wings of some aircraft to improve aerodynamics. The use of the device on aircraft can improve fuel efficiency by up to 4 percent on long-haul flights. Boeing said in a statement its new winglet will provide a total fuel-savings of up to 5.5 percent on the same routes.

"Incorporating this advanced technology into the 737 MAX design will give our customers even more advantage in today's volatile fuel price environment," Jim Albaugh, chief executive of Boeing Commercial Airplanes, said in a statement.

Winglets have become standard on the 737. Pioneered by research conducted by NASA, they help to improve fuel burn by reducing drag and getting more out of the wing by spreading the lift further out toward its tip. The downside is that their weight can force manufacturers to strengthen the rest of the wing, adding weight.

In its 40-year history, the Boeing 737 has become the world's most-sold aircraft and the backbone of airline fleets worldwide. But Boeing has taken several months to finalize the design of the upgraded 737 MAX while juggling engineering considerations, market opportunities and costs.

Last month, Boeing unveiled several design choices meant to lower weight and wind-resistance for its upcoming 737 MAX. The planemaker said it had decided on an 8-inch nose gear extension to give ground clearance for a larger engine fan.

Southwest Airlines (LUV.N) will be the first operator of the MAX, but Boeing won its first provisional order from AMR Corp's (AAMRQ.PK) American Airlines last year.

"We welcome advancements that will help improve our fuel-conservation efforts and reduce our carbon footprint," said AMR spokeswoman Andrea Huguely. "The cost of jet fuel is our largest expense, and fuel conservation is a huge priority for our company."

Boeing shares were up 4 cents at $77.29 near midday on Wednesday.

(Reporting By Kyle Peterson in Chicago; additional reporting by Tim Hepher in Paris, editing by Dave Zimmerman and Matthew Lewis)

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