Anyone remember the "6 Million Dollar Man"? Steve Austin had an arm and both legs replaced with bionic ones with super powers. He'd do thinks like break handcuffs by spreading his arms.

But only one of his arms was bionic. It would have just ripped the other hand off. Similarly, his running at superspeed would have just shattered his spine.

I.e. you can't increase the power of the engine without increasing the strength of the drive train.