Re: A Dumb Question

Let me throw the concept of a "normalizer" into this discussion. The ex-USG #1303 and #1403 are industrial GE 50 tonners with V12 Caterpillar D397 prime movers that were originally equipped with roots blowers. These 2 engines became GLRR, Inc. #130 and #140.
Apparently USG had continual problems with the roots blowers and the gypsum dust. At some point (I don't know exactly when but I think it was in the early 1970's sometime) they replaced the roots blowers with exhaust turbine driven air pumps, very similar to a turbocharger except they don't supply pressurized air to the engine, just the air volume required for the engine to operate. So, technically, are these engines considered turbocharged? They sure sound like it as the turbine whine is very discernible. But, again technically, can they also still be considered "normally aspirated" as the "turbo" replaced a roots blower and doesn't pressurize the air being delivered to the engine. Has anyone else heard of this kind of application? I can say it works very well on the #130 and #140 and seemed to solve USG's problems with roots blowers.
Phil