The Southern Railway in England had a class of 4-6-0 locomotives with four cylinders, the angular intervals, in degrees, between its four cranks being 135 – 90 – 45 – 90.
This resulted in eight evenly spaced exhaust beats per revolution of the drivers, resulting in what was called an eight-beat exhaust.
One of the class, No. 850, the Lord Nelson, has been preserved. At about 8:00 in this YouTube video the exhaust beats are distinct enough, and the view of the drivers unobstructed, so that you can clearly hear/observe the eight-beat exhaust.
https://www.youtube.com/watch?v=iD-dB_ub264