So im buying a 2001 accord ex 4 dr with an Si swap but i dont know what size or ouput the motor is going to be so i was wondering which motor would fit in the easiest and would most likely be it?

 

A civic engine in an Accord? This doesn't sound good...Stock engine is an F23a1, if that's what you were asking.

 

could be referring to the Prelude Si which would be the H23A1 engine, IIRC it makes 160hp and 156tq.

I doubt someone went through the trouble to mount a B16 into an Accord, that would take a lot of custom work with very little reward since that engine wouldn't have the torque required for the Accord chassis.