BMW Boxer Engine Centenary

Martin Stolle was a talented young engineer in the development department of BMW and he was having great fun riding his motorcycle from the British marque Douglas. After the First World War, his employer – like all German companies – was prohibited from producing aero-engines.

They kept their heads above water with large-displacement four-cylinder in-line engines for trucks, tractors and boats. A new product needed to be created in order to secure a permanent future.

Inspired by the engine powering his Douglas machine, Stolle designed a 500 cc, air-cooled twin-cylinder engine with horizontally opposed combustion chambers. This type of engine arrangement was already known as a Boxer engine, in which the pistons always operated “one against one” similar to boxing competitors in a fight. The power unit impressed aficionados with its outstanding smooth-running performance right from the start.

Martin Stolle with his Victoria powered by a M B engine
Martin Stolle with his Victoria powered by a M 2 B 15 engine – ca. 1921

In 1920, production of the new engine was launched. At that time, Stolle was just 34-years-old and his design of the Boxer engine was based on smooth-running and reliability. In his initial design, he settled for 6.5 hp at 4,500 rpm.

The new power unit was supplied to various motorcycle manufacturers under the sales designation “Bayern-Kleinmotor” (Bavaria Small Engine). And soon Stolle’s development was installed in motorcycles of the brands Helios, Bison, SMW (Stockdorfer Motoren Werke), Corona and Hoco.

The most successful motorcycles were manufactured by Nürnberger Victoria-Werke, whose KR 1 model powered by the “Bayern-Kleinmotor” from BMW attracted a large number of purchasers. More than 1000 examples of the first Boxer engine from BMW were installed in this model alone.

Two years after the launch of sales for the new BMW bestseller, Martin Stolle followed in the footsteps of “his” engine. He switched companies and moved to Victoria-Werke where he was involved in other successful motorcycle developments.

Production BMW R
Production BMW R 32, 1923

In Munich, Stolle’s legacy was not only a groundbreaking engine concept but also a pioneering inspiration for the future of BMW. The company was destined to move forward on two wheels. The development of a complete motorcycle had already begun. In September 1923, the BMW R 32 was presented – naturally powered by a Boxer engine.

BMW Engine Type 255 Kompressor
BMW Engine Type 255 Kompressor was a supercharged version of the Boxer from the 1930s that powered Georg Meier to victory at the Isle of Man TT in 1939

And now in 2020 BMW will release a new generation of the Boxer destined for a new retro range of cruisers and roadsters with a retro styled massive new donk dubbed the ‘Big Boxer’….

BMW Big Boxer Engine
BMW Big Boxer

Read here for more on the new Big Boxer