I have a question for you Prelude guys. The B21. What years did it come in, and what sort of power numbers are we looking at?

Also, is it in any way related to the B16/18?

 

i believe the b21 came in the 90-91 3rd gen Si. It made 145 hp.

apparently it is only loosely related to the b18/16 and can't be used for headswaps or other neato mods. I'm not a b series guy so i can't tell you why, exactly, but this is what i've heard.

 

I have been looking for an engine swap as well...but instead going to like a B16 or B18 or even the powerful H22. I think i would rather go with the B20C from japan...basically u are taking the CRV engine and sticking in your car...which means lots and lots or torque

 

I am assuming you are talking about a B20B or B20Z, since there is no such thing as a B20C. The B20B/Z would be just as hard to install as any other "normal" B-series engine (such as the B16A, B17A, B18A/B/C, etc)

 

B21A1 engine came in the 90 and 91 Prelude Si as compared to the 90 and 91 2.0Si with the B20A5 engine. The B21 isn't a great engine if it was abused as a child. It has a poor build quality compared to the B20A5 when it came to the cylinder sleeves.
Neither 3rd gen Prelude motor is worthy of swapping into any car to make it a speed machine. The B20 had 135hp and the B21 had 140hp and a little more torque. When in a stock setup the B21 spun faster than the B20 on the highway also.

Chris