FWIW a train I've taken a few times in China (Hangzhou to Shanghai) would do San Francisco to Los Angeles in less than 2 hours (possibly 1 hour 45 minutes). This would be an express with no extra stops.
With a handful of stops and the corresponding loss of speed (I'm extrapolating as it hits speeds of 350/kph but still takes about 45+ minutes to go roughly 186km) it would probably realistically take more like 2.5 hours.
With a handful of stops and the corresponding loss of speed (I'm extrapolating as it hits speeds of 350/kph but still takes about 45+ minutes to go roughly 186km) it would probably realistically take more like 2.5 hours.