12AT question
 

OK. Is the 12at from japan, injected, or carburated? Cause Ive heard that its powered by a "modded nikki", but Ive been findind things like computers and injectors for "12at"s. So, is the nikki modded so its just like a throttle body, or what?

Nikki made the carburetors and the throttle bodies for Mazda.

The 12AT is fuel injected (two 800cc/min injectors), non-intercooled, fuel-control-only computer. It has a "mechanical" distributor with centrifugal advance and vacuum advance/boost retard, similar to the B6T setup.

The 12AT intake manifold is great for people doing a turbo conversion, since it is really "pinched" at the bottom for turbo clearance, so you can use a 12AT manifold or a suitably modified 13BT manifold. Plus, the throttle body mounts vertically and has the same bolt pattern as the common carbutetor, so you can use the manifold to do a carbureted turbo setup using a suitably modified Nikki carb.

Hmm. Thought so. I dont know why everyone I have taled to or overheard ay it uses a modified nikki. Thanks.

As Peejay said the 12A T is efi, it uses a Nippondenso fuel only analogue computer and had low compression rotors. It was installed in Japanese only models, in the RX-7 performance was 145mph, 15.3 second 1/4 mile making it the best stock 1 gen produced.

The confusion arises when people add a turbo to a carby 12A engine with normal NA rotors, and call it a 12AT. The Nikki has to be modified to suit. However a Webber carb is often the carb used in the add on turbo modification.

Mazda never used the 12A T designation, but in Japanese literature said 12A turbocharged engine. In fact 12A is the only designation on the engine but there is a turbo symbol on the body plate. There is no lower case in Japanese so there never was a 12a engine, like cast on the engine it is 12A.

In the case of the 13B, they called it a 13B Turbo 11. Owners often simplified this to 13bt so some people adding a turbo to a 12A started using 12at as an unofficial designation.

What compression rotors are those, and how would I go about getting a set?