Though Otto had great success with his atmospheric engines, the really reliable and effective engine was not yet found. Otto was looking already for a long time for a solution of the problems which prevented the explosion engines from delivering a regular work: The burn was jerky. Otto finally found the right way. His improvements were fantastic: He learned how to let a mixture burn slowly and safely. At the same time, he could hold the performance of the engine on a high level by a compression of the gas.
In the year 1876 he built his first four-stroke engine. Wilhelm Maybach (1846-1929), one of the most important German engineers, perfected the construction, which was produced in large quantities already at the end of the year 1876.