If not, what engine swaps are possible with a 87 prelude Si?

I'd like to make my car faster...

 

every and any motor has potential , it just depends on how much money you are willing to invest in the already marketed parts and parts that you wold need to be custom made. so to answer you question does the a20 have potential : yes it does. is it cost affective, or worth it: probably not, however im sure there will be others that will tell you otherwise.