I remember reading about this before but I forgot what the differences were between the earlier ('90-'92) BP DOHC and the later ('93-'94) engine was. If I remember correctly, I believe somebody said that the rods were weaker in the older ones, but I'm not sure. The reason I wanted to know is because I finally got my motor I won on ebay to swap the block into my car... (my car has been parked for about 3 1/3 months, here's why ---> http://www.protegeclub.com/forum/sho...threadid=22734 ) Well I'm going to be turbo'ing this engine so I didn't know if I was going to run into any problems with this block or not. It seems to be in good shape and all cleaned up and all. So hopefully I can get this car back onto the road soon and without complication.

 

the *crank snout design* is the ONLY difference between the 90-4 BP; the 90 and possibly early 91 BP had the weaker design - but we just don't know for sure when they changed it.

also, there is no need to swap in the SOHC rods. if anything i think the miata guy was thinking about your pistons, as they would lower the compression - but even that is totally unnecessary....

 

yeah...that made me wonder if the miata guy knew what he was talking about