I don't see how the 101mph is possible because with 7 motors linked together like that only the torque and not HP would be multiplied, I guess maybe anything's possible. Another thing to consider is that 7 engines would weigh a whole lot, and I don't see the advantage when you can get 50-80cc dirtbike engines ranging from 6-25 hp and make a single engine mount. I wouldn't necessarily call it an exercise in engineering, but rather nice fabrication skills coupled with a "more is better" mentality. In reality, less is more if you want to repeately go fast and bring it back in one piece.
50cc -> 120+ mph