Last time I looked, it could only achieve its top speed of 150mph for 35 miles!
However the whole idea of Acela is incremental improvement. They did enough initially to make it viable, then Every year they knock a minute or so off the trip. The new train sets have a higher top speed so that should help, when they get into service. I recently saw a project announcement for replacing a tunnel near Baltimore where it was stuck under 30 mph. The new tunnel won’t be high speed but clear enough of a bottleneck to be a nice trip time improvement