jet engine thomas project

Did it come new in the box, or did it have any signs of someone trying to rebox it? In the latter case, it could be the previous owner put a standard Thomas in it instead of the faster, shocked one (for whatever reason). Otherwise, it might be a factory error. If a faster motor (with just a battery) won't give a better speed than the unique Thomas, you might have to put a two/three battery pack under the crates and wire it to the drive unit. Remember the DUs in old style engines have additional gearing to change speed and torque and allow freewheeling, unlike the TrackMaster 2 chassis. I reckon that sets a particular limit to what speeds they could be modded to reach.