Series 5 TII motor into a series 4
 

I cant find the thread about this, Can anyone tell me what I need to do? Ive got a pretty good idea but I want to be sure.

swap
 

The two things you need to be concerned about are:
1. Oil metering pump
2. High impedance injectors

I have the later 88 turbo and my swap went smooth. 1 Day with home tools. Your car has the older lower impedance injectors. The series 5 come with high impedance. You should use your old injectors for reliability reasons (ECU N332).

The series 5 also comes with the electrical oil metering pump, where as series 4 comes mechanical. You will need to use premix in your gas (2cycle oil) to keep the seals lubricated. I have been running this combo for quite a while and had no problems. I also use synthetic oil since my OMP is not pumping oil into the combustion chamber.

Good luck.

What about emissions? Will your car pass emissions on pre-mix? If so Im not going to bother swapping the front covers, ill just eliminate the OMP. I knew of the Injectors, the J-spec I just blew had the red-tops, and I switched them out with my yellows. Is there a way to retain the 89+ J-spec intake manifold?

emissions
 

If you want to pass emissions you need your original intake manifold. With premix you should pass no problem.....considering you still have the air pump. And you dont need to change front covers at all.

what problems will you run into if you replace wireing harrness and computer? should the swap need anything else? what would you need other than what a j-spec motor from nippon?

Cool, I dont have to swap on my front cover :) Will a series 4 oil pan fit a series 5? The last J-spec I got had a sensor missing on the oil pan, so I had to use my old one.