My memeory fails me on this particular item (it fails me on a lot of items!), so I will check when I am at the museum on Saturday. I'm pretty sure that it has a Roots-style blower, because pressurize air is required to scavenge the exhaust on a 2-stroke engine, since there was no seperate exhaust cycle. I don't think I have ever heard of a naturally-aspirated Detroit or EMD without a blower. I should make clear that this is distinct from turbocharging, and some later EMD road switchers had both turbochargers and blowers (or superchargers, as you call them). This was called turbosupercharging. Occasionally a railroad would "de-rate" a turbocharged engine by removing the turbocharger, largely becasue of the maintenance costs of the very expensive turbochargers.
For the uninitiated, a blower (or supercharger) is a gear- or shaft-driven device for moving large volumes of air through an engine at relatively modest pressures. A turbocharger, on the other hand, is driven by the exhaust stream of an engine and is used to increase power by significantly raising the air pressure entering an engine, allowing for more fuel to be injected into the cylinders, hence more power. Occasionally you will see photos of 4-stroke diesel engines (i.e., GE's) shooting flames 10-15' above the engine. That is a sure indicator of turbo failure. On a blower-equipped engine like the 6-71, if the supercharger breaks a gear or shaft, strips a gear, or eats a small rock, the engine simply dies for a lack of air. There are access doors on the sides of Detroit Diesel and EMD engine blocks to allow access into what is called the "air boxes," which surrounds the inlet ports of the cylinders. If you find metal filings at the bottom of the air boxes, you know you have a blower failure impending.
Mike
IMHO, of course.
Mike
