GE´s 747 testbed is a long-retired Pan Am jumbo, first delivered in 1970, outfitted with dozens of computer banks that track temperatures, pressures and stresses in and around the engine-up to 1,500 measurements in all. At 128 inches in diameter, the engine itself is more than 3 feet wider than the JT9D next to it. It´s also more than twice as powerful, having earned a Guinness World Record for 122,965 pounds of sustained thrust during a particularly taxing ground test. Following the â€greater airflow equals greater thrustâ€ rule, the engine features high-flow composite â€sweptâ€ fan blades that squeeze out 3,000 pounds more thrust than those of its predecessor, the GE90-94B. There´s also a nine-stage high-pressure compressor-one stage fewer than the 94B-also for increased airflow.