Complex sentence: Power output of the SD24 was 33 percent higher than the of the concurrent Roots blower-equipped SD18s with the same engine displacement, per axle, limited by the traction motors then available.
Split into simpler sentences: Power output of the SD24 was 33 percent higher than the of the concurrent Roots blower-equipped SD18s with the same engine displacement. The SD24 had per axle, limited by the traction motors then available.