Those familiar with the Z3 and Ti know they share a lot- both were offered with the M44 engine and the e30 style rear trailing arm suspension. Lots of Ti enthusiasts (like me) are attracted to swapping an S50/52 into the ti due to the great power/weight ratio (Ti=2750lb dry, lighter than a Z). But there are tradeoffs (heavier front end, hard to keep ASC, more power=bigger brakes, diff, the price of a good S52, etc) if you still want this to be a daily driver that might see snow, carry a child, etc. So how about the 193hp M52? Affordable and plentiful. What about the Aluminum block 2.8 from a Z3? 60lbs lighter you say? Even better.
Here is what I am wondering- could it be cost effective and yield a better result to buy a good condition 1998-1999 2.8 Z3 at auction and swap the
entire drivetrain and suspension into my 103k mile 1999 Mtech 318ti? I'm talking motor, trans, electrical, ASC, rear subframe, diff, axles, shocks, springs, wheels- from one car to another? You would end up with a 328ti to drive and a 1.9L Z3 to sell back onto the market. I think a +/- 80k mile Z3 might sell for $8000 at auction while a 105k mile 1.9 Z3 with the right colors and shined up might go for the same.
The thing that kills me is the labor- I guess the only way to justify this approach would be if having the cars side by side in operable condition makes everything easier.
What would not work between these 2 cars? Not sure about cooling systems or brakes (I cannot find specs on 2.8 Z3 brake diameters anywhere). I think the 328tiz would be nice in stock form though the shocks might be tired at 80k. I have a 3.45 LSD that is the same as the 1.9 Z came with too.
All thoughts are welcome but be forewarned I'm married to the cali-roof Ti for now so no "Eff that dude buy an M3" comments please.
2.8L Z3 drivetrain swap? (opinions please) 
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