May be the twin-turbo version from the 13B engine meant to energy the 3rd-generation RX-7 released in late 1991. Each individual rotor on 13B-REW has just one combustion chamber quantity of 654cc. With two rotors, the whole displacement was 1308cc. Great in shape for your Mazda swap or substitute job. https://13b-engine-for-sale-japan49269.blogrelation.com/35822291/a-review-of-custom-rx7