Notching a floor joist will do more to weaken it than drilling a small (3/4" or less) in it's center. Engineered or standard lumber the worst thing you can do is cut the top or bottom edge. They both work the same way, only engineered products are more consistent. With a load on the floor, the top edge is in compression and the bottom edge is in tension, and the center is mostly free of stress. If you notch a 2x8 1" deep you just made a 2x7 out of it.
The size of hole you can drill without affecting the strength of the joist depends on it's size.
