Info für Besucher ohne Javascript

Premium

Mercedes-Benz and the miracle Wankel

This article was auto-translated. We apologize if some words are confusing or simply amusing. Would you like to help us improve?

Created on August 8, 2025

Text:

Karl Ludvigsen

Photos:

Archiv Karl Ludvigsen

28

Archiv Karl Ludvigsen

28

Daimler-Benz created space for its own team to design, build and test various Wankel types. In the foreground are parts of various model series

When logged in, you see more images in larger size.

Photographer Julius Weitmann effectively staged a Wankel rotor housing in front of a complete engine

When logged in, you see more images in larger size.

Felix Wankel began with flat rotary valves for engines. This Mercedes-Benz Type 612 V-12 used these, as the flat cylinder head surface reveals. The work ended in 1942

When logged in, you see more images in larger size.

In February 1957, Felix Wankel was able to present the rotor of his first successful "Wankel engine" - here the rotor and housing were rotating

When logged in, you see more images in larger size.

On the first Wankel, both the red rotor and its housing were turning. The engine turned smoothly up to 12,000 rpm, but was difficult to supply with ignition and fuel

When logged in, you see more images in larger size.

NSU chief engineer Walter Froede had the inspiration to reverse Wankel's principle: with a fixed housing. This patent protected the ingenious design

When logged in, you see more images in larger size.

Difficult to describe: The Wankel rotary motion - here counterclockwise - always processed three states simultaneously, all of which had to be taken into account

When logged in, you see more images in larger size.

Julius Weitmann also portrayed Wolf-Dieter Bensinger inspecting a rotor. Bensinger was determined to make the Wankel ready for series production

When logged in, you see more images in larger size.

The internally lubricated and cooled Daimler-Benz rotor carried a gear wheel that rotated eccentrically around a smaller fixed gear wheel

When logged in, you see more images in larger size.

Six Wankel rotors side by side show the tested variants of the pockets in their end faces - in search of the most efficient shape

When logged in, you see more images in larger size.

Heinz Lamm, supervisor of the successful Mercedes-Benz sports and racing engines of the 1950s, also managed Stuttgart's Wankel program in the 1960s

When logged in, you see more images in larger size.

Somewhat unwieldy: One of the KP series engines from 1962, intended for training Daimler-Benz engineers. This two-rotor version tested fuel injection

When logged in, you see more images in larger size.

In the early KP phase, Daimler also tested single-rotor Wankels. This example with gearbox indicates road use

When logged in, you see more images in larger size.

At 450 cm³, the KA series from 1966 had the smallest chambers of all Daimler Wankels. This two-rotor version has complex intake routing and Bosch injection

When logged in, you see more images in larger size.

With the KE engines - here a twin-rotor - the Daimler testers experienced Wankel drive in a passenger car for the first time: a completely new feeling of smooth running

When logged in, you see more images in larger size.

The KC series from 1967 onwards provided further insights into running behavior. This front-mounted engine ran without the usual oil sump and with numerous inlets

When logged in, you see more images in larger size.

Dynamometers played a central role in Wankel development at Daimler-Benz. This three-rotor is shown here running with open exhaust pipes

When logged in, you see more images in larger size.

A cutaway model of the K series from 1969 onwards shows the higher air intake with throttle valve at the top and the double-walled exhaust pipe at the bottom

When logged in, you see more images in larger size.

Multi-rotor motors inevitably required partition walls for the inlet and outlet. Here is the arrangement for a three-rotor KE

When logged in, you see more images in larger size.

During rotation, the rotors deliver their power via circular elements offset to the "crankshaft" with large bearings inside the rotors

When logged in, you see more images in larger size.

When assembling a Wankel engine, the precise "sandwich" is created layer by layer - tolerances on surfaces and sides must be precisely adhered to

When logged in, you see more images in larger size.

At Daimler-Benz, the Wankel was never produced automatically; instead, the units were built up piece by piece to the required number of rotors

When logged in, you see more images in larger size.

Equipped with a manual passenger car gearbox and Bosch injection pump, this 5.4-liter KE three-rotor produced 280 hp at 7000 rpm

When logged in, you see more images in larger size.

When journalists visited the Wankel plant in Untertürkheim, Rudolf Uhlenhaut posed with a partially assembled KE three-rotor - he nevertheless remained a cautious supporter

When logged in, you see more images in larger size.

Long intake pipes to the inlet of a three-rotor CE gave the airflow a ram effect, which increased power in the mid-range

When logged in, you see more images in larger size.

A late-developed three-rotor Wankel from Daimler-Benz attracted attention at exhibitions - but was never used in a production Mercedes

When logged in, you see more images in larger size.

Dressed up for the show: A 7.2-liter KE four-rotor produced 350 hp at 7,500 rpm - many considered it an ideal sports car engine

When logged in, you see more images in larger size.

A beautiful day at Lake Constance as a break from work for Wolf-Dieter Bensinger (left) and Felix Wankel - a productive partnership for the new engine

You have only

1 out of 28

images seen in high resolution

Summary

Controlled intake valves, slide valves, turbocharging and direct injection were among Daimler-Benz's proudest achievements. How could the brand have resisted the appeal of Felix Wankel's rotary engine? It at least had to give it a chance.

This article contains the following chapters

The man behind the engine
In Heidelberg
Research in the Third Reich
The original Wankel
Wankel and Mercedes
The further development
The K-series
At the limit of what is possible
The end of the story

Estimated reading time: 10min

Preview (beginning of the article)

Daimler-Benz had good reason to be at the forefront of those companies experimenting with Felix Wankel's rotary piston engine. Long before the Second World War, some Daimler engineers were already acquainted with the ambitious inventor from Heidelberg. Felix Heinrich Wankel was born on August 13, 1902 in Lahr, a small town on the Rhine in the Swabian south of Germany, close to the French border. The Swabians, often the target of German jokes, were regarded as rustic and stubborn - but even Rhinelanders and Berliners had to acknowledge that the modern combustion engine was perfected by three Swabians: Otto, Daimler and Benz.

Welcome to Zwischengas!

Continue reading this article for free?

Images of this article

Source: