BMW: engine swap, combustion chamber, engined cars

Question
Josh, I have read the questions regarding 'i' heads on eta blocks, but they are written from eta engined cars. I have a 1989 525i. What are the problems with putting an eta block into into an 'i' car? Do you think it would be a waste of time?  

Answer
Joe,
 There aren't really any problems with doing this.  In fact I have this exact setup in my '87 325i convertible.  There is a common misconception that you will make more power with this engine than a standard "i" engine.  When you put the "i" head on the "e" block, you loose compression.  "i" pistons are dome topped, and the "i" head's combustion chamber is larger to accomodate this.  When you put this larger combustion chamber on top of the dished "e" pistons you loose compression.  It drops from 8.8:1 to ~8.0:1.  This is relatively low for todays standards.  So now you have longer stroke, which equals more torque, and mathematically it should yield higher HP, but due to the loss of compression it really ends up making about the same HP as you had before.  The good thing about this engine is that it really adds some low end torque, and in the 5-series that's not a bad thing.  If you couple it with a decent rear-end ratio then it could really shine.
 But to completely answer your question, YES, you can put the "e" block into your car and use the "i" head with it.  
 Good luck!
 Josh