What exactley are the differences between the engines? For instance: what are they between the 12a and 13b (aside from the different size) And also for the G series.

Maybe this could help.



http://www.monito.com/wankel/engines.html#Mazda

Here's another.



http://cp_www.tripod.com/rotary/pg19.htm

There's really no rhyme or reason to it. The first engine of a given displacement (number code) is "A", the next is "B". The 13A was a 1310cc engine, the 13B is a 1308cc engine, and the 13B is just a longer 12A. The 13A is not, and is not related to the 10A or 12A.



The 13G/13J engines make no sense to me, either. What happened to the C/D/E/F/H/I? Not to mention that the 13G was a three rotor, and 13J a four rotor, based on 13B dimensions. The 20B was Mazda's second production engine of its displacement, so the B in this case actually sorta makes sense, except for the part where the original was a 13G and not a 20A.



Remains to be seen if the new RX-7 engine will be a 16A or 16B. Logically it should be a 16A. My bet is Marketing, which knows no logic, will insist on the name 16B.

i didnt know they were making one..

Somehow half of my reply is missing.



The gist of the truncated part is that Nissan used a similar naming arrangement on the L-series engines in the 70's. Nissan's L-series encompassed the six and the four cylinder engines of that architecture (SOHC non crossflow engines, mainly Mercedes-Benz in design) and the original six cylinder was a 2 liter, called the L20. The four cylinder grew from 1.6 to 1.8 and finally to 2.0 liters, and Nissan named the 2.0-liter four the L20B so as to avoid confusion with the earlier L20 six.



Mazda's naming convention is similar, except the original has an A at the end. The 3mm iron seal, single distributor, single side seal 12A was originally to be called the 12B, but Marketing decreed against it. There is engineering literature that refers to the engine as a 12B. Arguably, the 2mm seal, soft seals in the side housings 13B should have been called a 13C, and the side exhaust port engine should have been called a 13D. It would greatly avoid confusion for us. But Marketing will always have its way.

There was already a non-production 15A. Will the larger displacement rotary have 10mm wider rotors, or 20mm?

10mm wider would be a 1471cc rotary displacement engine (which is what the 15A was/would have been if it weren't for OPEC's antics), 20mm wider would be 1635cc rotary displacement.



I certainly hope they are putting a third main bearing in there, with 100mm wide rotors and the necessarily longer eccentric shaft!

i didn't know they were making one either. do you have a link for it?