I have a volvo 850 NA. and I was wondering if an engine swap with an 850 turbo would be as easy as putting in the new engine and taking the ecu from the turbo engine and putting that in too. Also I was wondering what the mechanical differences between a NA engine and a turbo engine are other than the turbo and exhaust such as are the valves and spring different is the compression ratio different.

Compression ratios are different.

Throttle body sizes are different.

Injector sizes are different

Etc...

I would seriously just sell your NA and buy a turbo Volvo. For all the grieve your going to go through it would just be easier.