I posted about this about on preludepower but all I got was some idiot who wanted my B21 cams for free...

Anyway... I have a '91 Prelude Si with a B21A1 in it. I would like to bolt a GSR head onto the B21 Block. Now I know this can be done, but all I need to know is how (necessary modifications, etc) How much work it is, and how much it would cost (rough estimate)

 

I have heard that the early Prelude B-series were the red headed step childs and are not compatible with the more common B-series.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by excivicboy96 &raquo;</TD></TR><TR><TD CLASS="quote"> I have heard that the early Prelude B-series were the red headed step childs and are not compatible with the more common B-series.</TD></TR></TABLE>

Yup. Other B heads are not a bolt on.They have weak rods and an unusual main girdle/cap setup.The scrap metal guy has brought a few around.They were seriously blown up.

 

b21a's are not related to any b series. i dont know why honda gave them the "B" series name but they are not the same.

 

Don't get the old Prelude B series engines mixed up with the B16-B17-B18A/B and B18C engines. They are totally different.

 

I learned that from the book "Honda Engine Swaps" By Aaron Bonk.

 

So Basicly the only head that will work is the stock head?

 

yes

 

I always wanted to experiment a P13 head on the B21A1. Find someone that has an H22 head laying around and see if it'll bolt on.

I wanted to try this because if you look at the JDM F22B, the H23A1, the B21A1, and the B20A5, they look exactly the same.

 

It is possible to accomplish this head swap...some guy actually made a kit for it. He discontinued selling it because it seemed to be a lil too complex for the average person. I remeber his write up saying that you need to use a b16 head b/c of the manifold design, a gsr manifold will hit the firewall. Unless you used a gsr head and skunk 2 manifold. Anyways the head swap will cost you more than it would to just put an H22 swap in the car, so its kinda pointless. But go for it if you want a unique car...just don't rev it over 7500 or what ever the "blow the expletive up point" of that motor is.

And remeber, unlike an ls/vtec or b20/vtec setup you can't just swap over to vtec water and oil pumps, so you will prolly shorten the life of ur bottom end.