Most people believe traditional piston engines create the most power. Rotary engines challenge that notion. Invented in the 1950s, the Wankel rotary engine uses a simplistic design that allows all the internal components to spin in one direction, as opposed to the piston engine that uses pistons moving in different directions. The rotors spin on an eccentric, or e-shaft. As the rotor spins, the air in the combustion chamber is brought to and from the housing. The air expands and contracts, which results in combustion. A rotary engine can create three revolutions per rotation, resulting in much more power per liter than its piston counterpart. Mazda is considered the king of rotary engines and is continually experimenting with designs. Previous Rx7 models used the standard 12A and 13B engine series, which produce over 100 HP with 1.2 to 1.3 L of displacement. The 20B rotary engine features a triple-rotor design that manages to produce 300 HP from its 2.0 L of displacement. Find a large selection of rotary engines available through reliable sellers on eBay.Shop the large inventory of motors, parts, accessories, and complete car and truck engines!