I have a 86 n/a rx7 and i have a s5 t2 motor with tranny, wiring harness,mass air flow, and ecu. First of all how would i start with the wiring harness, will it just plug all up or will i have some problems since im puting an s5 motor in a s4 car? Another question, can i bolt the t2 motor to all the n/a drivetrain because i was going to drive it until i get the rest of the t2 rear end. Im also making the car power steering, do i just need the lower half of the rack and pinion or will i have to change the whole thing? And one more question, will i have to get a s5 radiator?

 

This gets covered on a regular basis!!! I believe there is even a detailed write up on what needs to be done, probably in the archives or the FAQ. It is not plug an play by any means. I don't know what needs to be done off the top of my head, so do a quick search and your questions will be answered.

This has also been covered often. You will need to put N/A flywheel and clutch on the T2 engine and then it will bolt up just fine to the N/A drivetrain, IIRC. Keep in mind you will need a S5 flywheel as it also acts as a balancer for the engine.

You don't have to but you might have trouble getting the air out of the cooling system. You will probably be just as well off putting the S4 neck on the S5 waterpump.

 

Read up on swapping the electrical S5 components for mechanical S4 turbo ones (omp, tps, emissions), so you can just use the S4 NA EM harness, front harness & instrument cluster. If you're here asking how to even get started on putting that motor in your car, you're not ready to tackle a series swap. It will be a re-wiring nightmare. The front harness runs through half the car, so the S4 can't just be switched for the S5. Besides the cluster not being plug n' play, the connections between the EM harness and front harness do not match up.

A series 4/5 hybrid will be the way to go; it will be far easier.