This piece of thundering Fairbanks-Morse iron is probably model 31AD18, which makes it 3500 hp (4700 kW) at 277 rpm. Multifuel, it will burn diesel or natural gas, and drives an alternator to produce electric for a municipal utility. This engine will run for decades... HAS run for decades... without major repairs.

Note how well this plant is maintained. These engines ARE running in these pictures! No leakers allowed :) That little stool at the back allows you to sit alongside and feel its pulse shake the foundation.

I've had the pleasure to visit the F-M plant in Beloit, Wisconsin, where this beautiful machine was built, though I don't have pictures inside.
http://www.furaffinity.net/view/15286534/

You simply have to love any engine big enough to require a hand railing around the cylinder heads, right?