May be the twin-turbo version of the 13B engine created to energy the 3rd-generation RX-seven launched in late 1991. Each rotor on 13B-REW has only one combustion chamber volume of 654cc. With two rotors, the total displacement was 1308cc. Great in good shape for the Mazda swap or replacement job. https://donovanlhdwo.bloggerswise.com/46925083/rx7-engine-fundamentals-explained