I found some obscure info about the motor used, which is an Alstom ONIX 800.
I'm not 100% sure if it uses IGBT.
IGBT would give it better performance compared to older types of power controllers.
http://www.uic.org/cdrom/2001/wcrr2001/pdf/sp/1_11/555.pdfI don't notice anything particularly special about these onix 800 motors or the cummins diesel engine.
From my understanding, IGBT can handle Voltage droop better by upping the amperage, so that total power sent to the motors remains unaffected, but it can't pull more power than is supplied by the engine. Conversely, that means the unit can pull more power than it is rated for, if it is on external power.
Since these voyager trains only have 2 driving axles per car, which makes it 1 Motor, 1 Trailer, it shouldn't have particularly good acceleration. Although, for an express train, it's better than average or the class-43 that it replaced.
compared to the electrostar family of trains, which are 4M1T, 3M1T or 2M1T, voyager series should not out accelerate them.