13B rotary engine

https://derrimutwreckingyardpost.ironwoodscope.com/posts/why-the-derrimut-wrecking-yard-is-a-goldmine-for-mazda-rotary-enthusiasts

The 13B rotary engine is a unique powerplant that uses spinning triangular rotors instead of pistons, delivering a smooth, high-revving character that's instantly recognizable. Found in classic Mazdas like the RX-7 and RX-8, this two-rotor design produces a distinctive exhaust note and offers a lightweight, compact package with impressive horsepower for its size.