Is there any difference between a J-Spec 13B or 13B that came in American RX-7s

 

Not much, the only things I can think of offhand is the lack of an EGR on the JDM S4 engines, and the different wiring harness made for their RHD body.

 

Not much. Just some emission equipment. Check this out:
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/whats-difference-between-2-a-287616/

 

Following posted by Jason-NZConvertible:

No EGR (S4)
No AWS
Different ACV with no split air solenoid
FPR and PD in opposite locations
Twin-scroll actuator on opposite end of exhaust manifold (S4)
No thermovalve on TB
No air bleed to secondary injectors (S4)

 

Just so you know... there were no NON turbo Jspec engines.

All Jspec FC engines are Turbo.

 

thanks guys

 

So there should be no problem runnin a j spec 13b or motor parts in a American 7 especially if you go standalone?

 

Just use your existing wiring harness, assuming that you are turbo and have the same series engine. Be careful though. Jdm importers will not warrantee or even compression test rotary engines. You could buy something and it will run, or you could spend $1500 on $100 worth of scrap metal.

What exactly are you trying to accomplish? A swap or a replacement?