I’ve been doing a lot of research about this lately because I’m doing an M50 or M52 swap on my ti track car. Of course I want to use the lightest weight, best power potential engine available. So below is the short block engine weights as advertised on
www.realoem.com Listed from lightest to heaviest.
M44 318ti 95.5kg/210lbs
M52B28 Z3 ONLY Aluminum block 117kg/258lbs
M52TUB28 Z3, E46 etc. Aluminum block 127kg/280lbs
M54B30 Z3, E46 etc. Aluminum block 130.5kg/288lbs
M52B28 E36, E39 etc. Iron block 135kg/298lbs
M50TUB25 E36, E34 etc. Iron Block 135kg/298lbs
Sorry to revive this old thread ... just thought I would add some good info to complete it.