NSU Wankel rotary engines and cars
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NSU, from Germany, was the original partner that developed production versions of the rotary engine with Dr Felix Wankel. As NSU had several patents on the rotary, all other manufacturers had to pay a license fee to NSU. This is in fact cast into every Mazda rotor housing saying "NSU-WANKEL LICENSE"
Two rotary powered NSU cars were produced, The single
rotor NSU Wankel Spyder (which was the first production rotary car in the
world) and the twin rotor NSU Ro80 (Mazda beat NSU to be the first production
twin rotor engine with the Cosmo Sport, by 3.5 months).
A brief history of NSU
NSU started in 1873 making sewing machines before making bicycles ten years later, followed by motorbikes at the turn of the century.
It wasn't until 1892 that it got the name NSU. Motorcycles were first produced in 1901.
The first cars appeared in 1905 and were produced until 1930 when Fiat bought the factory in Heilbronn. Production of bikes and motorbikes continued and Scooters and the well known "NSU Quickly" were manufactured from the early 1950s. In 1955 it was the largest motorcycle manufacturer in the world. Production of two wheeled vehicles ceased in 1965.
1957 saw the return of NSU to the car business with the Prinz 1, a small aircooled rear engined car (583cc 2 cylinder). This was followed by the Prinz 2 and Prinz 3, then the restyled Prinz 4 with a larger 598cc engine. The Sport Prinz was procuced alongside the Prinz 4 with both the 583cc and 598cc engine.
A range of larger 4 cylinder cars were also made based on the same body shape as the Prinz 4. The first was the Prinz 1000 later badged as the NSU 1000 with a 996 cc engine.Two high performance models followed, the TT and the TTS. The TT had a 1085cc then 1177cc engine with twin carburetters. The more powerful TTS had a 995cc engine with two twin choke Solex carburetters.
The largest of these NSU saloons were the Type 110 and NSU 1200 with a 1085cc and 1177 cc engines respectively.
NSU also produced the first two Wankel Engined Cars, the Spyder and the Ro80. The Company was absorbed by the Volkwagen-Audi Group (Around 1977).Their final design for a conventional watercooled front engine later appeared as the Volkswagen K70.
NSU Engine Development - Introduction
In 1951 contacts were established with Felix Wankel. Dr Walter Froede was the first to visit. He was director of NSU's motorcycle racing program. It was his recommendation that led to NSU's collaboration with Dr Wankel.
DKM supercharger (Left)
Wankel's first work was on rotary valves and rotary superchargers. One of his designs was attached to a 50cc NSU motorcycle, boosting the air pressure 45psi to increase the horsepower to 13.5 bhp. This cycle set a world speed record for its class of 120 mph at the Bonneville salt flats.
By 1953 Froede had become head of research and development. NSU's head engineer was against rotary engine development, but a year later Wankel and Froede persuaded the board to allow engine research if Wankel would share the patents and not receive any increase in consulting fees.
NSU Engine Development - DKM motor
Because all the components in the DKM spin around their own axis they can be completely "naturally/internally" balanced (just like a turbocharger wheel which can spin at 100,000+ rpm with no vibration), the engine does not need any counterweights (like a Mazda rotary does). This allows RPM levels limited only by the strength of the metal - even back in 1957 they attained 17,000 rpm. Perhaps using current materials 40,000 rpm would be possible.
In spring 1954 Felix Wankel in conjunction with his long time associate Ernst Höppner, realised that a triangular rotor running in an epitrochoidal bore could form the basis of a four stroke cycle engine. (This was after discarding a four-lobed design.)
DKM 54 engine (Left)
The experimental unit was named the DKM 54
Testing began in January 1957. Unfortunately management had personality conflicts with Wankel so he was not invited on February 1, 1957 when the DKM 54 was fired up for the first time on the third try. The fuel was based on methanol. Gasoline was first used in April, yielding 15 bhp at 9000 rpm. The engine ran for two hours by the end of May at 21 bhp. By June 1958 it had survived a 100 hour test.
The chamber volume was 125 cc., best performance 29 hp (DIN) at 17000 rpm, engine diameter only about 260 mm, shaft offset 9.5 mm. Three spark plugs rotated with the inner rotor.
Four units were built but the DKM 54 remained the only NSU DKM type engine ever constructed. One of them got its due place in the Neckarsulm (Germany) Museum.
NSU Engine Development - KKM Motor:
In 1957 NSU abandoned the original DKM concept as it was was far too complex a mechanism ever to go into production and all further research work was concentrated on the planetary rotation KKM type, which was invented by Dr Froede
KKM engine ("Conventional Rotary")
This was a fundamental change to Felix Wankel`s original idea and in this way the very high engine revolutions were partly lost. It was also not as smooth and had more sealing problems (since the apex seals experienced greater forces because the rotor orbited the stationary gear.) However it had other advantages, not the least of which was the engine did not have to be disassembled to change the spark plugs
Felix Wankel is reported to have said that they had transformed his racing horse into a cart horse.
KKM 250 (Left)
In 1958 two engine types were built and successfully tested. This confirmed
the principle of the KKM system. As of 1960 an experimental KKM 250 was
fitted into the small NSU Prinz. The engine output was approximately 30
hp (DIN) at modest 5000 rpm. Between 1960 and 1964 a large number of engine
types was developed and installed into a variety of applications ranging
from lawn mowers to boats.
The provisional result was the KKM 500 which became operational in the
NSU Spider as type 502. However, further development and introduction to
the public was delayed because of serious technical problems which arose
from the gas and oil sealings and other components.
Many manufacturers showed interest in the new rotary engines
because they were smooth, powerful (for their capacity) and had the potential
to be easily manufactured. As NSU had the rotary engine patented, companys
wishing to make their own Wankel rotary engines were required to pay a
NSU required license holders to share research results with all others
(although GM obtained an exemption). This was important because there were
only seven years between the first engine test and the first production
automobile, compared with nearly a hundred years of development of the
NSU Wankel Spider, 1964-1967
NSU first road tested the Wankel in 1960, later that year they showed a preliminary version of the Spider at a Munich meeting of German engineers. Wankel spoke to the conference and won over the many skeptics in the audience.
The production NSU Spider was unveiled at the 1963 Frankfurt
Automobile Show and was the first car to be powered by a Wankel rotary
engine. The car was a convertible version of the "sport prinz",
styled by bertone and was normally fitted with a 598cc 2 cylinder piston
The single-rotor engine type KKM 502 had a 498 cc chamber
volume and developed approx:
NSU Ro80, 1967-1977
Development of the Ro80 began in August 1961 and it was
officially shown at the 1967 Frankfurt Auto Show.
The car was well received by the public and the press,
however it suffered from major engine problems which resulted in the demise
of the company. Some cars were converted to conventional V4 engines (I
think these were Ford V4s from England/Germany). However modern materials
have fixed some of the engine reliabilty problems (using modified Mazda
parts), some Ro80s are being converted back to their former glory.
There was three rotor successor being planned in 1969
using the KKM619 3 rotor engine with 3x 498 cc chambers, producing around
150-180 bhp (pictured above). However this was when the Audi/VW takeover
occured, so development ceased.
The downfall of NSU
On 10th March 1969, NSU and Audi (100 % owned by Volkswagen)
formed Audi-NSU Autounion AG. (The name NSU was dropped from the company
name in 1984, at which time NSU GmbH was formed as a seperate company).
Internal politics, finances and conservatism snuffed out rotary development
and hence production of the Ro80 ceased and the assembly line re-tooled
to produce Audi models.
NSU Gmbh still exists, although they do not make anything (they have a staff of 3-the boss and 2 secretaries). In 1997 the factory celebrates its 100th birthday. It is rumored they have one new car left in the stores compound (either yellow or orange in colour) which has been there since the company ceased production.
I do not know a lot about NSU engines and cars. Much of the information
here has been compiled from other places around the net, as when this page was
originally written there was little available in English. The text has been
re-written in my words.
If there is any pictures belong to you (and you don't
like it) let me know and I will remove it.
Other relevant reading at Craig's Rotary Page (Please go via the INDEX
Other relevant sites on the Internet (Please go via the LINKS
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This page last updated 17/3/2001
13/12/2001 - Fixed a few broken photos and tidied up a bit.
17/3/2001 - Modified More Information section, Spell check, Converted all text to new standard (Headings as Heading1, Some sub-headings (e.g. tables) as 14 point normal bold italic, Most text as Normal, Internal page links at top not all uppercase), Changed from Netscape to FrontPage. Background image changed to PG00_02B.JPG
31/10/1997 - Previous known update (May have been some before this)
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