motoxxxman

i have a 1989 prelude si beater car with a b20a5 motor with a recently rebuilt head; new valves, seals, and guides. i recently purchased a 1990 prelude si with a b21a1 motor that i am going to be rebuilding with all new bearings, rings, gaskets etc etc, and need a lil b-series tech advice. havent pulled the b21a1 motor apart yet, but was curious if the b20a5 head is able to be bolted up to the b21a1 motor retaining the factory b21 intake manifold. also, i did some research on the two heads and found the b20 to have 9.0:1 compression while the b21 has 9.4:1 compression. as far as differences between the heads, the only stat i can find is the fact that the b20 has 47.3 head cc's, while the b21 has 51 head cc's. can someone tell me what the new compression ratio might be if i put the b20 head on the b21 block? i dont need any knocking goin on in the '90 due to using 87 octane gas lol. and last but not least, if i put the b20 head on the b21 block will i run into any interference issues as far as the valves with stock cams and/or mild cams? keep in mind my 89 b20 is a beater car, and the 90 b21 i just bought is in absolutely flawless condition, so the 89 will become my parts car for the 90. thanks for any help i can get. oh, also, i am an experienced mechanic and am completely comfortable doing full rebuilds on just about any motor, as i have hundreds of times.

oh, and i will not be racing this b21a1 lude, for all who wonder. the most i may do for mods is a 4-2-1 header, a mild cam, and removing the air box for a FREE factory cold air intake as the factory cone filter is clamped directly to the main rubber intake pipe.
it shouldnt matter as far as a head swap question, but the b21 and b20 are both auto, the b20 auto slips in first and fourth, and the b21 auto works flawlessly. i do have a 5spd out of a lude si, although i am unsure if its from a b20 or b21, i believe its from an 89 or 90. i was told it will work for both motors, but am not sure. an answer to that would also be appreciated; whether a 5spd from a b20 will work with a b21, and whether a 5spd from a b21 will work with a b20. thanx.

motoxxxman

come on people, doesn't anyone know anything about b20's and b21's? need some help here... thanx