is there a difference between n. american and j-spec 12a?

 

Yes in both the case of RX-7 models and engines. For example Japan had a series off short run specials made for marketing purpoises such as the 'Spring Shot. Perhaps the biggest difference was in 1984/5 with the 12AT and 13B DEI engines.

There were also other different export models such as the European and Australian to cater for their marketing needs and government regulations.

In total there were some 40 RX-7 Gen 1 models.

If you interested in a specific year just specify.

 

Plus, to further muddle the issue, there are some SLIGHT differences between Canadian and American models of the 1st gen...:p

 

There's lot of wiring and accessory differences as well, it was a pretty flexible car.

 

North American 12As made about 100hp while the J-Spec engines had like 14,000hp and could rev to twelve million RPM.

But seriously, a lot of J-spec 12As were 6-port engines. I dunno if these were standard equipment or optional but they first staretd showing up around 1981.

 

Yes but only because north america uses a different system of measurement, most of it has to do with which side of the road you drive on....not to mention 100hp gained from a right hand drive vehicle, pretty simple really

 

The 12A 6 port injection engine was first produced in 1981 for the Cosmo and Luce models. It was then used in the Japanese model RX-7 in March 1982. The North American market did not get this engine but continued to receive the 12A 4port engine. This is surprising as the concept of the 6 port was to improve fuel efficiency rather than performance. The later 12AT was also a 4 port engine but with turbo and efi. Again North America did not receive it.

It must be remembered in the early 80s, the Cosmo was Mazda's performance car and thus got engine improvements before the RX-7 which was slower.