Hi all,

It's been a while since I posted. Some of you may remember I've been looking for a N/A motor for my 90GXL for about a year now. I've come across a few 86-88 motors and no 90+ motors. I'm just trying to get this thing running so I'm running out of options. I'm thinking about trying to put a 86-88 motor in it. My questions are: what do I need to swap? will it affect the car? should I swap just the short block or the whole motor?

I've heard that the 90 uses an electrical oil pump while the 86-88 uses a mechanical pump. I've also heard that the 90 has 8.5:1 compression whereas the 86-88 has 8:1. I basically just want to get this thing going and out of my driveway (where it has been for the last year). So can this be done relatively painlessly? I'm very familiar with mechanics; I'm just new to rotaries. That's why I don't rebuild the motor in addition to the fact that I can get a motor cheaper than a rebuild kit.

Thanks all,


E

 

You are kinda of correct, the '90 motor uses an electronic oil metering pump, which injects oil into the motor for combustion. The 86-88's use a mechanical system that would be difficult to adapt to your car because of the error code the computer with have without receiving any signals from the stock electric OMP.

I wouldn't just try and wing it with the 86-88 motor, it has less hp. The compression of the 89-91 N/A motors are actually 9.7:1 while the other one's a believe are 9.1:1. The 89-91 also has lighter rotor's.

It might be possible, if you don't care about the lower power numbers, but you'll also have to find a way to adapt the fuel injection system and intake to your current style, along with finding a way for the 6-ports to activate. There are a few subtle differences that make them non-functional between the two series.

At any rate, I know all this because I'm adapting my '90 motor to the '87 chassis, and it's got some issues. Your best bet would be to find a used 89-91 motor and have it shipped, or a cheap rebuild. Good luck!