Originally Posted by
Jon_g2
... If swapping out a bottom bracket will help in any way be more efficient than I will go with it
...steel bearings and the bearing race surfaces are highly polished. It would be difficult to measure much difference in efficiency between any two particular BB units, if both are working well. The best ones are probably less efficient, because the seals on them to exclude dirt and water can drag just a tiny bit.
It's too bad you don't have access to a big old box of sealed unit BB's. You could spin them and see what I mean. There are a lot of places you can lose efficiency in a cycling machine. The BB is not one of them, so long as the bearings and races are in good shape, and the lubricating grease is not too thick (you can't control that, it comes with the unit you buy, already built into the sealed bearings).