by Irish Chieftain
Is it possible to use a standard freight engine (like SD 70 ACE , SD 70 M-2 , Dash9 or GEvo) to haul passenger trains?Not at high speeds. They tried that with the SDP40F and SD45 and that didn't work out very well. The F40C didn't operate faster than 70 mph on its tracks (officially). The U34CH and P30CH might have performed better, but there are no definite records of such. "Standard" freight engines (which originally were built for "special" duties—note what SD stands for on the EMD locos) are built with a bent towards hauling tonnage at relatively low speeds, not for high-speed stability, sustainability and trackability with passenger trains.
The GEVO is a prime-mover, not a locomotive; and GE might make that available in a new Genesis if anyone's interested in buying the series again (although what top speed it may be geared at is certainly up for debate).