Would be the twin-turbo version from the 13B engine built to ability the 3rd-generation RX-7 introduced in late 1991. Each individual rotor on 13B-REW has only one combustion chamber volume of 654cc. With two rotors, the overall displacement was 1308cc. Great fit to get a Mazda swap or replacement job. https://jdmmazdaengine57902.blogpostie.com/51966738/detailed-notes-on-rx7-13b-motor-for-sale