Dear all.

I would like to know if you could tell me how to identify MFR housings castings, and what are the pros/cons on each casting.

I just purchased an old track racer that had one type of casting, and many years ago purchased an engine from Jos Boon (Mazda team europe) that was used in rallying the Rx-7 Grp. B.

Look at the photos and share your thoughts. The smaller port is of the rally engine.

 

those look to be the same casting? i'm not an expert but in the US we only had 2 part numbers

4801-10-100 which is from the 79 style competition engine, and a ZR03-10-B10 which is a 13G part number. mazdausa actually superceeded these numbers to one part number. i believe if you order a ZR03 you'd get a 4801, that is if either were available, which as of a couple years ago they weren't.

so they are both the same, one's been ported...