MiyaKokujin

I guess this mod is known as the S4 to S5 engine swap in the states. I know that these two engines are very different but bolt up the same way. I already have the (1991) Kouki engine, ecu, and engine harness in hand. All I need to do is swap out the two motors in my (1989) Zenki FC. What exactly do I need to do?? I keep getting different answers. So Id appreciate any knowledgeable information from anyone that knows what they are talking about. Thanks!!

ForsakenRX7

Well you already have the engine, ecu and harness. Theres not much more left to do but drop it all in. Stateside the 89-91s are the kouki motors or s5s. someone please correct me if I'm wrong about the years but I feel very confident that thats right. The differances that I can think of between the two were internal (higher compression rotors for example), emissions controls (S5s have no egr valve for example), and the flywheels weigh less on S5s, and of course the turbos. There are other differances but as far as swapping them out there isnt that big of a differance between the two to hinder the swap in any way. Also try search this site. A lot of useful info can be found that way as well.

SureShot

I assume the engine has the solinoid rack.
I can't think of any suprises. The main fan is different, but the fan shroud dimensions are the same.
Different upper radiator hose - stuff you replace anyway.

Madrx7racer

ForsakenRX7 is right Zenki(86-88) and Kuoki(89-91)