Hey so I have a 91 si with a d16a6 and I want to know if I can put in a d16 engine out of a 92-96 civic in my car and still keeping it obd0 ?

 

You could probably get away with putting in a d16y7 while using the original intake manifold and distributor. You won't be able to run a d16z6 or d16y8 on the stock ecu.

Unless the block is no good just leave it alone, you gain nothing.