So I have an 01 A6 2.7 and somewhere down the road I am sure the engine will get old. So is the newer A6 with the 3.0 turbos compatible with the 2.7? Without modifieing the engine bay?

 

I have an 1998 audi a4 2.8, that needs an engine replace. Would an engine off a 1999 audi a6 2.8 fit on it?

 

As for the 2.7t/3.0t, the 3.0 is actually supercharged, not turbo.

I'm sure it'll go into the bay, but it'll cost a fortune to get it to work right. You'll certainly need a new transmission (highly doubt they're compatible) and ECU, and...well the list goes on.