FAQ – What is the Mazda JDM 13B?

FAQ – What is the Mazda JDM 13B?


The Mazda JDM 13B Engine represents the flagship rotary series engine in a long family of powerplants dating back to the mid 60’s. Like it’s relatives of yesteryear the new 13B is a tremendous engine for power and a remarkably effective engine given it’s displacement.

Many people believe the 13B engine is an upgrade from the 13A, when in fact it’s an upgraded version of Mazda’s 12A engine featuring thicker (3.1 in.) rotors and a displacement of 1308cc. Available in the United States via the mid 80’s Mazda RX-7, the Wankel didn’t make a return until the triumphant FD RX-7 in the mid 90’s. In Japan however, this engine was used from the early 70’s all the way through the early 2000’s, ending in the 2002 RX-7.


If you are looking for a motor swap, the possible candidates can vary depending on your purpose of use. The RESI 13B is Mazda’s Rotary Engine Super Injection system which incorporated a two stage intake box that helped low engine speed velocity and improve mid range driving. This 13B can be found in the late 1970’s Mazda Cosmo AP or and the RX-4 and RX-5 in Japan, through 1980. With 135 horsepower and 134 ft lbs of torque this is a basic JDM engine swap.

The 13B Mazda continued developing the 12A engine and in 1975 the first Mazda JDM 13B engine was released. Actually 13B was a lengthened version of the 12A. Having bigger rotors thus having a bigger displacement, 1308 versus 1146. 13B was first introduced as naturally aspirated. But later on single (13B-RE) and than twin turbo (13B-REW) versions were produced. As the power of the engine increased, developments were made to the engine. The high stress areas were reinforced to cope with the high load caused by the turbochargers. Intake and exhaust ports were redesigned so was the oiling and cooling systems. The newer versions were also more reliable and more fuel efficient thanks to Mazda’s great effort on these subjects.


The next generation of Mazda JDM 13B is the turbocharged 13B-T in the 1986 Mazda FC3S (146hp) RX-7 as well as the S5 version which put out 160hp. This engine is highly sought after because the engine ditched the cumbersome variable intake system in favor for the tried and true four port design. The S4 RX-7 used a twin scroll turbo system with variable VSV, much like other turbo Japanese supercars like the Toyota Supra. The later S5 version from 1989-1991 featured an upgraded divided scroll turbocharger which improved response and power.

From here the choices get a lot more interesting from the 13B-RE and the JC Cosmo, which is basically a beefed up FD RX-7. Bigger injectors and a larger turbocharger system, this JDM JC Cosmo engine is as rare as they get. There is also a 20B-REW which is almost impossible to source and can be very prohibitive to import or purchase.


The latest version of this famous family line is of course the Mazda JDM 13B-MSP Renesis which is found in the late model RX-8. Although initial horsepower levels were incorrect, it’s proven to be a very durable survivor in the game of performance JDM engines. Like many other engines like may be too advanced to be truly appreciated, it does not diminish the engineering hallmark that the Renesis represents.