I recently bought an 89 vert that someone had put an 86 block in, and Frankensteined the rest of the install (89/86 parts, cut up harness, junkyard spare parts). A 90 NA engine & transmission also came with the car (guy wanted to get rid of everything). Can anyone tell me if there's any difference, or point me to a thread listing differences between the 89 and 90 engines? I have the 90 engine, transmission, ecu, and harness.

Thanks!

 

Here are two links that may help.

Rotary Resurrection: Differences between 86-88 S4 engines and 89-91 S5 engines

Rotary Resurrection: Swapping an 86-88 (S4) engine into an 89-91 (S5) car

 

I dont think there is a diffrence between 89 and 90 engines i believe its 86 to 88 and 89 to 91.Of course there is a diffrence between 89 and 90 N/A engines and 89 and 90 Turbo engines.

 

thanks guys - that should help out. Looks like I need to check the wiring/ecu under the dash, and see if they put an S4 ecu in, or left the S5, and the rest should just be a pull and swap.

I'm going to clean up the '90 motor before I put it in - replace fuel lines, master cylinder, etc on body. I'll start a build thread as soon as possible, and start posting pictures.

 

The easiest way would be to check what AFM/MAP sensor/TPS the engine is using. If they're all still S5 ('89-'92), odds are the wiring and ECU are still S5. But there are no guarantees, so I'd still check over it all. An S5 AFM is round, while an S4 is rectangular, and an S5 TPS uses two "plungers" instead of one. An S4 MAP sensor should have a sticker reading N32x (I think there were both 326 and 327, but I'm not sure offhand) for the part number.

Other than that, '89-'92 engines are the same.

 

The 13b n.a engines for s4 and s5 are basically the same but the 6 port actuators, air pump, injectors, ecu plugs, wiring harness plugs are all different. If I were you I would swap the s5 engine into the car. Putting an s4 engine into an s5 is kind of downgrading the car since the s5s were known for being "updated" vs. the s4. Horsepower ratings are slightly different also but not by much.

 

yeah, that's what I'm doing - pulling the 4 and installing the 5.

 

Good thinking I would be doing the same thing!

 

89-91 NA engines/wiring harnesses are all identical (unless it's a convertible harness with air bag connectors/wiring added on). Hopefully the guy didn't mod the car's dash/body wiring harness too badly, and your new engine with it's matching wiring harness would drop in and plug up and everything will be back to normal.

There's not much wrong with "frankensteining" in a different block IF the person doing it knows what they are doing, but that is usually not the case, and it leads to a clusterf**k.

 

what?

no.

the 86-88 NA and 89-91 NA share only a handful of parts, including the e-shaft, stat gears, oil pump/drive, etc. Almost EVERYTHING internally and externally has been changed or redesigned slightly. Sure, most of those parts don't offer a major performance change, but they sure as heck aren't easy to mix and match if you don't know exactly what you are doing. Don't be giving this guy misinformation, he's confused enough by the previous owner already.

 

Hey invinciblerx, ever hear the joke: if I wanted to hear an ******* Id fart? Way to be a dick. I know what Im talking about Ive had 4 FC's ALL N/A so blow me mr i know everything there is to about a rotary and i have to prove it every chance i have.

Posted above:

The easiest way would be to check what AFM/MAP sensor/TPS the engine is using. If they're all still S5 ('89-'92), odds are the wiring and ECU are still S5. But there are no guarantees, so I'd still check over it all. An S5 AFM is round, while an S4 is rectangular, and an S5 TPS uses two "plungers" instead of one. An S4 MAP sensor should have a sticker reading N32x (I think there were both 326 and 327, but I'm not sure offhand) for the part number.

Other than that, '89-'92 engines are the same.

 

Invinciblerx, I know that the s4 to s5 engines are vastly different. For someone who isnt tearing down and rebuilding the engine but just doing a simple swap like this guy is they arent concerned with every internal parts being different. His main problem is having the s4 harness in the car with the s4 engine (if that is even how it is set up) because I know for a fact the s5 harness plugs will not work with an s4 for a good deal of the plugs. His best bet is to take out the wiring harness s4 engine and install the s5 harness and s5 engine being that the car originally came like that. There is nothing wrong with putting an s4 engine in an s5 except the fact that the engine has alittle less power and TO ME it is like downgrading the car. Why go backwards when Mazda designed the s5 as an updated s4. I can name tons of things changed between the s4 and s5. Ive had a lot of FC NA RX-7s so I dont see where you get off thinkng Im wrong and that somehow its funny. On top of it all dont tell me what to do, youre wasting your time. If I am so wrong then explain why someone who knows a hell of a lot more then I do posted above something similar? Refresher for you.

[QUOTE=RotaryRocket88;10977712]The easiest way would be to check what AFM/MAP sensor/TPS the engine is using. If they're all still S5 ('89-'92), odds are the wiring and ECU are still S5. But there are no guarantees, so I'd still check over it all. An S5 AFM is round, while an S4 is rectangular, and an S5 TPS uses two "plungers" instead of one. An S4 MAP sensor should have a sticker reading N32x (I think there were both 326 and 327, but I'm not sure offhand) for the part number.

Other than that, '89-'92 engines are the same.[/QUOTE]