What 's better a 84mm b16a or a 84mm b18c? also what would the power difference be?

 

you would get more torque w/ a b18c, so if you have the money get that.

 

its the difference of a 1.8 to a 2.0

thats about it as far as displacement wise.

 

If your willing to sacrifice displacement then B16 is the way to go. The rod/stroke ratio is of the best at 1.74:1. It gives a little less sideload on the pistons and allows you to spin worry free at 9,000+rpm. (with a built bottom end of course)

Ryan