How does a Wankel rotary engine work in a Mazda RX-7?

The RX-7's 13B rotary uses a triangular rotor spinning eccentrically inside an epitrochoidal housing rather than pistons moving up and down. Each face of the rotor creates intake, compression, combustion, and exhaust phases simultaneously. The twin-rotor 13B-REW in the FD3S produces 255-280 hp from 1.3 liters displacement. Rotaries rev freely and are lightweight, but require meticulous oil injection maintenance and periodic apex seal replacement.