b21A1 swap in a 87 si

[Ethernal]

i need some expert advise, from someone that really knows what they are talking about.

is it a bolt in swap? how easy would it be?

[PWMAN]

never heard of a b21, unless it's a B20 bored out.

[crxlvr]

yeah what car is a b21a1 from?

[PWMAN]

Well, since no one has heard this engine - I will tell you this, all B series requires a mount kit to be put in your civic. Your car now has a D series, and they don't mix. You have to change tranny's and axles too.

[diegoaccord]

B21A1 is a 90-91 Prelude Si motor.



B20A3 88-91 Prelude S

Carb SOHC 100 HP
-------------------------------
B20A5 88-91 Prelude 2.0Si

PGM-FI DOHC 135 HP
-------------------------------
B21A1 90-91 Prelude Si

PGM-FI DOHC 140 HP

[PWMAN]

Whoa yeah what was I talkin about anyway. He said SI, and somehow I thought thats a model of a civic when I wrote it. I wasn't smokin crack or anything, just had a brain fart I guess. I have no idea what engine is in in 87 SI prelude so I can no longer comment on what engine fits.

[94tegRS]

whats the r/s of the B21, is it better or worse than the B20b?

[EF You]

its worse. in fact, ive heard that the b21 is the worst b-series motor ever made. lots of rod problems or something along that lines. my friend has a 90 S that we are converting to fuel injection, and eventually putting a b18c1 or c5 into, depending on his cash flow by then end of the summer.

i think the 87 prelude has and A series motor like the old accords, but dont quote me on that.

[PreludeX]

is your 87 FI? if so than its a b20a5.. umm and far as the the b20b and b20a.. totally diffrent motor.. another thing is b21a1s have really bad oil burning problems! and for the guy with the 90 and goin to put a b18c or c5-- waste of time! ull be better off with the H22A than either of those cuz the motors sit totally diffrent and then ud definatly have to get custom mounts!

[PreludeX]

Look at the engine code to find out! it located where the tranny and block meet! pretty easy to see.. its a flat spot!

[Ethernal]

as for the oil burning, i dont care. if its a new engine, it wont burn for a while. its an 87 SI, with the b20a5 i think. all i want to know, is if i need new motor mounts, a mounting kit, or if it is just a bolt on. thanks for the help everyone, but im not asking for opinions. i just want to know about the procedure.

[GundamExpo]

This wont help your mounting question but I do have some info on the care and feeding of a B21A1. What I gather from browsing posts on preludepower.com is you have to change the oil ever 3000 miles. The piston sleves are made out of some kind of carbon composite and the piston rings chew them up, if I remember right. Supposedly it was an experiment by honda that went horribly wrong.

You might be interested in a JDM B20A

I think its got something like 143HP and a little less torque then the B21A1

[ayupit]

hey I am trying to put this little project together. if you guys are saying that the b21a1 motor is bad do you think that I could put another head like the b18c1 on it and make it better?

[EF You]

not gonna work. the head bolt holes dont all line up. neither do all of the coolant passages.

besides, the head isnt the problem on the b21a1. its the block. its got some experimental coating on the cylinder walls that fails with high mileage and causes them to burn oil.

my buddy with a 90 prelude S is building a b20a block with a b21a1 head on it, and then converting the car to fuel injection. probly not gonna bother with a b18c1 now.

[mikeymackinon]

i will be back to up date my info shortly