The 33 Engine Booster startup sequence appears to involve 16 different engine groupings. After the center 3 engines ignite, the remainder spin-up 2 at a time (opposite pairs) until all 33 are lit. This is based on observations made during today's spin prime testing.

🎥:@LabPadre pic.twitter.com/5HPY3wR87q

— Zack Golden (@CSI_Starbase) September 13, 2022