The Mazda R26B has the distinction of being the only engine made by a Japanese manufacturer to win the 24 Hours of Le Mans outright. In 1991, Mazda faced frequent criticism of the Wankel rotary engine as an unreliable gas guzzler.
To silence the naysayers, Mazda set their sights on winning Le Mans. Calling upon the foundation
laid by its 4-rotor predecessor, the 13J-M, Mazda added a number of
refinements and racing-derived features. These included intake ports on
the periphery of the rotor housings, telescopic intake runners
(variable height tuned to engine RPM), 2-piece ceramic apex seals, and
3 spark plugs per rotor instead of the usual 2 to reduce fuel
consumption. This produced a motor capable of developing 900 hp
at upwards of 10000 rpm, although it was detuned to ~700 hp (some say
even as low as 630 hp).
Unfortunately, because of changes to Category 2 regulations the following year (more weight and a reduction in the fuel allotment in order to make way for the 3.5 liter Category 1 cars), the fantastic R26B was not able to continue to shine as part of the Mazda's racing repertoire.