I have a 1987 base modle RX-7 and I have the chance to get a 89 S5 turbo engine with tranny. Does any one know if i will need a wiring harness? I know I need the CPU. I'd like to get more info on the coversion before I buy this enigne.

 

This info is in the FAQ. Generally speaking, cross-series swaps are a major pain in the butt. You need all the S5 wiring for the engine, S5 ECU and related, and you will have to significantly modify much of the other wiring to accomidate the changes. Much easier just to run the S5 engine on the S4 turbo electronics (swap on S4 TPS).

 

yeah dude, you need to search. try to stick with the same series if you can, it will save you a lot of money. but first things first, you do need to search forum. all your ?s will be answered.