What's the main differences between a 12A and a 13B? is it just the fuel injection and minor differences in porting? or is there more to it?

 

Rotor size is bigger too, I believe.

And you forgot the 13A.

 

I don't think there was a 13A, but I really wouldn't know.

 

Yes there was. It was in the R130.

 

The rotors and rotor housings on a 13B are 10mm wider than on a 12A. Now how 'bout the 10A?

 

also i think the exhaust and intake studs are in different locations so you can't swap those parts between the 12A and 13B?

 

anyone interested to buy 1977 RX 3 SP

 

12A and 13B rotors are different widths, therefore the housings are different widths. That is why the exhaust and intake studs are different.

Another difference is the ports. The 12a has 4 ports. The early 13b has 4 ports and the turbo 13b has 4 ports, but the 13b N/A has 6 ports.

Also motor mounts. 12a motors all had their motor mounts on the front covers, along with the early 13b. After the 86 RX7, the 13b had motor mounts on the side..

Even with all their differences, it is amazing how many parts can be swapped between all the rotary engines.

 

could somebody explain the A and B after the number(13B,12A,13A)

 

But generally speaking, If I put a 13B sourced fuel injection system onto my 12A - could I expect the same power output? Or would I need to upgrade other parts like the oil pump and fuel pump?

 

Fuel injecting a 12a wont get you the power of a 13b if that is what you are getting at. Generally speaking switching from carb to fuel injection will get you very little additional power. You also couldnt just put a 13b fuel injection setup on a 12a because as was mentioned earlier the intame manifold wont fit. You will need a custom setup of some sort.