#Focus – Mazda & The 4 Rotor R26B Engine.

Mazda is still the only Japanese manufacturer which has won the 24 Hours of Le Mans to this date, this was back in 1991 when the #55 Mazda 787B GTP car driven by Johnny Herbert, Volker Weidler and Bertrand Gachot triumphed over Jaguar and Mercedes thanks to the “economie run” strategy held by the manufacturer.

The 1991 24 Hours of Le Mans winning Mazda 787B.
The 1991 24 Hours of Le Mans winning Mazda 787B.

Not only it was the first victory for a Japanese manufacturer but also the first and only victory of a rotary engine at Le Mans and this is what we’re talking about. The R26B 4 Rotor Mazda engine.

Mazda 4 Rotor R26B Engine as fitted to the 787B.

First and important, let’s sum-up what a rotary or Wankel engine is :

The engine was invented by German engineer Felix Wankel. He received his first patent for the engine in 1929, began development in the early 1950s at NSU and completed a working prototype in 1957. NSU subsequently licensed the design to companies around the world, who have continually improved the design.

The Wankel engine is a type of internal combustion engine using an eccentric rotary design to convert pressure into rotating motion. Over the commonly used reciprocating piston designs the Wankel engine delivers advantages of: simplicity, smoothness, compactness, high revolutions per minute and a high power to weight ratio. The engine is commonly referred to as a rotary engine.

The Mazda R26B engine was and is still the ultimate evolution of a long series of rotary engine. Build on the basis of the 4 rotor 13J-M engine seen in the Mazda 767B, itself a variation of the 3 rotor 20B, the R26B beared a number of refinements such as intake ports on the periphery of the rotor housings instead of the side plates (as seen on all Mazda rotary production engine) in order to produce a much greater airflow potential at high rpm.

Mazda 4 Rotor 13J-M engine.
Mazda 4 Rotor 13J-M engine as fitted to the 767B.

Another of the interesting features seen on the engine was the steplessly variable intake runners, a way to optimize intake length and airflow at any engine state as well as the 3 spark plugs fitted to the engine in order to optimize the burning of the fuel/air mixture.

All in all, the engine was capable of arround 900 HP at more than 10 000 RPM but only 700 HP were used for the race to ensure durability.

Mazda R26B Engine Diagram.
Mazda R26B Engine Diagram.

Now, let’s enjoy the Rotary sound and their difference !

Mazda 767B with 4 Rotor 13J-M engine fitted.

Mazda 787B with 4 Rotor R26B engine fitted. The 1991 Le Mans Winning car.

 

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