there were 3 types of civic hb from 88-91...the std that came with a 70 hp dpfi engine, the dx which came with a 92 hp dpfi engine, and the si with came with the 106-108hp mpfi engine...there was no hf level civic hb...it only came in the crx lineup

a way to tell if you have the std over the dx is to look at the tranny...is it a 4spd manual or 5spd manual...if its the former (4spd) then you have the slowest hb of that year and to do a swap it requires you to replace out the front knuckles for the dx or si units b/c the std come with smaller weaker axles