McDonnell Douglas built the MD-90 to replace the MD-80. The MD-90 was quieter, more fuel-efficient, and fitted with modern high-bypass turbofan engines that the McDonnell Douglas MD-80's noisy, smoky JT8D-200 engines could not match on any engineering metric. The Boeing Merger Ended The MD-90’s GrowthBoeing completed its acquisition of McDonnell Douglas in August 1997, inheriting the MD-80, MD-90, and MD-11 programs. When Boeing discouraged further McDonnell Douglas narrowbody orders in favor of the 737 Next Generation, Delta's future narrowbody procurement shifted accordingly. The JT8D-200 was louder, thirstier, and less efficient than the IAE V2500 on every chart that McDonnell Douglas produced when it launched the MD-90.