Atomic Systems

How do you make the AI/Computer controlled engines go over the speed limit of 35-40 as I am creating a run-away activitie with James and Edward (thomas the tank engine) and I can't get james going faster tham the speed stated above

set the start speed to 888m/s by editing the consist in note pad (maxvelocity line), It should slow down to about 60/70 mph very quickly and stay near that speed