Hey guys I'm new to this group my name is Dimitri my friends call me D. I did a few searches for swaps but found little info maybe you guys can help.
I have a 1987 turbo II I found a S5 turbo II engine but can't find the harness or ECU do I have to get the Harness and ECU for a S5 engine or can I do without I read that there are quite a few differences but all the ppl I call tell me to bring them the car and the engine and they will do the swap for approx 2 grand. I am learning to be a mechanic and thinking seriously about learning all I got to about these types of engines. Thanks again

 

https://www.rx7club.com/forum/showth...threadid=26647

Look in the FAQ. Do a search on swapping engines. Alot of people here will give you a hard time not looking in the FAQ or not doing a search. There's TONS of info about swaps. I'm in the middle of doing one, but I'm doing a S5 NA to S5 TII...

 

im doing the same s4 to s5 swap, but honestly i havent found much of anything of major use. most of the write ups that iv found consist of "line both motors up next to each other, strip both, swap everything" if you look around you can get little bits of info, and that is what iv been doing, but just so you know.....
on the s5 the omp is eletrical, so, this leaves you with two options, (btw, the omp is that feeds oil to the injectors, known as the oil metering pump) one you can block it off, (http://www.2751engineering.com/2751parts.html) or you can swap the front housing. with blocking off the omp you will be left with no choice but to run two stroke oil, do a search if you want to look more into this, the plus side to swaping the front housing is you get to use your mechanical omp, and you wont run into problems like where to put coolant in (since the s4 rad doesnt have a place to put coolant in) and you wont run into the problem that i have about the s5-s4 coolant temp sensors. you will have to swap your injectors, since the s5's are high impedance and the s4's are low, i wouldnt recomand doing anything else like tring to make the s5's work with resistors, its just easer to swap them. your s5 throtle body is different from your s4, along with the tps, the black box on the tb, (s5 will have two, s4 just one) so you need to swap your s4 tb and tps. im still unsure wether the s4 upper and lower intake mans are needed, i plan to use my s5's unles i find out different. if course you will have to use your s4 mass air flow sensor, the s5 turbo works fine. and you'll notice on the bottom of the s4 oil pan there are two lines running out of it, the s5 has just one, i just noticed this today so i dont know if the oil pans need to be swaped. all in all there is alot of differences between the two, breaking it down to short block would probably be your best bet and just swaping everything with the exception of the turbo and a few smaller things. but if not, this should help you enough to give you a head start.