LMAO @ the mr.potato head style comment.
Sorry, I'm not doubting your mechanical ability.......wait, I guess I am
No, but seriously, are you SURE you are trying to loosen it and not tighten it? Seriously. Hey I have to cover all the bases here.
You should not be moving the entire motor.
Here's the deal, its not about strength when getting a bolt off its about LEVERAGE. You said you used a 1 foot pipe to extend the breaker bar? That is your problem, all of your effort is going into moving the motor on its mounts. Go get a 3ft, better yet a 4ft small diameter steel pipe just big enough to slide over the handle of the breaker bar. If you get one long enough, your little sister will be able to break it loose. Its about leverage not strength.