Basically I'm looking at a cheap 87 FC, but I was hoping for an 89+ Car because the egine is more powerful. Are there any changes with the newer N/A 13b that prevent a direct swap? What are the key difference between the engines? Thanks guys, please bare with the new guy...

 

I know that the internal difference are that the newer engine has lighter rotors and a higher compression ratio, but are there any external things I would need to worry about?

 

no as long as you use all the parts from your s4 engine your good to go you do have to change out the front cover. as the oil mettering pumps are totally different. and the main pulley bolt is put on by king gong at mazda 250 foot pounds it's a bitch I've had trouble even with my 3/4 inch impact so if your going to put on a under drive pulley do it at the same time ( highly recommened to go under drive) I've done this swap on my daily driver and definatly a noticable difference