Boeing is finalising the wind-tunnel testing which will enable it to determine the thrust requirements and performance of its 737 Max family.
Identifying the thrust demand from the CFM International Leap-1B powerplants will confirm the type's maximum take-off weight and range. Meanwhile, the airframer is dismissing rival Airbus's focus on the Max's smaller fan diameter compared with the A320neo.
"Physics doesn't work in Europe the way it does everywhere else," says Boeing Commercial Airplanes vice-president of marketing Randy Tinseth.
He says both airframers are designing thrust requirements around their largest re-engined aircraft - the A321neo and 737-9 - but says the Airbus twinjet needs 20% more thrust, and this allows the 737 to employ a smaller core and smaller fan. Tinseth adds that the A320's empty weight per set is higher than the 737's - by 5-10% across the family range - and the larger A320neo fan will simply add more weight to the aircraft.
"We've worked hard to optimise the performance of the [737 Max]," he says, insisting that weight affects the operating costs in terms of fuel-burn, maintenance and landing charges.
He also believes Airbus is using "seat count games" to suggest its A320 matches the efficiency of the 737-800, and states that assessment of configurations shows the 737 has a higher seat-count and a 7% advantage in terms of fuel burn per seat - a figure, he says, which will rise to 9% with the Max.