This three engines have common roots.
Describe the roots, the history of development history of the different versions, as well as the technical design and technical data of the three versions in all its details, for a whole point.
Up to Experts.
Forced induction
Yes, they are supercharged engines, but this is not the main root.
Villiers?
No.
Are these race bikes?
Yes.
Adjustable pressure superchargers?
I don't know exactly, but I don't think so.
All the same manufacturer?
All have a closely related basis, but built in different workshops.
German?
Yes!
4 stroke engines?
No!!
2 stroke?
Yes!
Are these Roots superchargers?
They are superchargers, but not according to the roots principle.
Centrifugal?
Do you mean Zoller or rather Centric?
I mean centrifugal mechanism rather than screw type. Also the Zoller brand was almost one of my earlier guesses.
Let's make it easy: it is a Zoller-type.
Thanks, so similar to a Mazda rotary rather than fixed rotors
So air compressors not air displacers.
Yes.
Photo 2 and 3 the same engine?
Not the same, but very closely related.
Wankel engine?
No, 2-stroke.
Up to profs.
Opposed piston engine, also known as a counter-rotating engine. Is a reciprocating internal combustion engine in which two pistons work against each other in the same cylinder and share a common combustion chamber in the middle of the cylinder.
Developed by DKW-engineer Manfred Prüßing in 1935, with Centrix-compressor.
After the war, in 1949, DKW/MZ-engineers Kurt Bang and Erich Bergauer built such an engine for race-rider Kurt Kuhnke. Installed it in an 1939 DKW-race-bike-frame, with Matchless-fork. The one-off Kuhnke Sport KS1 250 from 1949/1950
picture attached, showing the principle of this engine
Here the Kuhnke-Sport KS 1
Hey fromwien, you are the first user, who goes deep in this puzzle.
Picture two and the connection with K. Kuhnke are explained. But there are different ambiguities and gaps.
So, it's locked for three attempts to clear following questions:
- Development of the engine from image one
- Prüssing and opposed-piston motor
- the engine from image three is anything but an overhauled engine.
1) DKW GS250/350 1946/47 with Zoller-Kompressor?
2) Kuhnke Sport KS1 1949/50: The Braunschweig private racing driver Kurt Kuhnke subsequently hired Kurt Bang and Erich Bergauer from the Chemnitz design team and had his own water-cooled, supercharged opposed piston racing engine with two cylinders and four pistons designed. The debut took place in 1950 at the Braunschweiger Prinzenparkrennen as Kuhnke Sport 1, KS1 for short. The output of this two-cylinder 250 cm³ engine was around 45 hp at 7,000 rpm. A compressor ban by the International Motorcycle Association (FIM) brought the sporting career of the DKW opposed piston engine to ist end.
Prüßing: Beginning in the second half oft he 20's August Prüssing installed the largest motorcycle racing department of its time at the DKW-factory. Riders like Ewald Kluge, Walfried Winkler, Arthur Geiss or Toni Bauhofer won several road-races, eight European motorcycle championships and 23 German championship titles on DKW factory machines up to the Second World. In addition, DKW riders set numerous world speed records, especially in the small displacement categories of up to 175 and 250 cm³.
After the Second World War, the Soviet military administration SMAD in Chemnitz forced the former DKW racing manager August Prüßing to develop and build five racing machines with two-cylinder opposed piston compressor engines and four pistons each. These water-cooled machines were transported to Russia with all documents, cast models and devices in 1948 in order to be used in the two-wheeled technology center Serpuchov in the following years in Russian road racing.
I heard about another DKW-rider, Karl Heinz Meller (Hamburg), who rode his own constructed race-bike, equipped with this DKW-developed, water-cooled and supercharged opposed piston racing engine
Your description of pictures one and two are very detailed and precise.
Now please a few comments on picture three.
The information about K.-H. Meller is new to me.
Seems to get a very hard nut for me to crack, as I haven't found considerable differences between the two engines of pic 2 and 3.
Shows one picture the original KS 1-engine and the other one the restored TU-Darmstadt-version by Hermann Herz? Or does it show one of the four built 350 ccm-engines, which took the way to Russia?
Picture three shows the result of the work of the TU-Darmsatdt staff. The difference to the motorbike that belongs to picture two is so big that this motorbike does has been preserved as an oldtimer according to FIVA-rules. Please describe the differences in the design of the motorbike and the redesign of the engine.
Frieder Bach and Heiner Jakob tell a story of the Saxon engineering spirit in their book "THE LAST TWO-STROKE COMPRESSOR-ENGINE WITH DKW GENES":
Heiner Jakob's (one of the editors) comment, according the 'restored' KS1:
For Frieder Bach and for me, the book project was more than just research. It opened our eyes to see how 'truths' arise. What we humans perceive to be true is the product of our understanding of the world. As soon as we investigate, more and more often our view turns out to be a mirage. When an internationally respected expert like the now deceased NSU and DKW collector Hermann Herz from Lampertheim presents a motorcycle to the public as a 'DKW opposed piston racing machine' and thus causes a stir at all the major classic car events, an image solidifies and shapes the media reporting the public perception. Years ago when I wanted to point out that this machine was a fake, my text was 'editorially' edited. Herz was a legend even in his lifetime. He enriched classic car events at home and abroad with his numerous and incredibly perfectly crafted racing machines, which he had often built from fragments based on famous models. Not so with Kuhnke-Sport 1.
Then he created a historically worthless pseudo-DKW factory racing machine from the originally preserved and historically significant one-off. He also communicated the history of the machine according to idiosyncratic ideas, although he had all the facts, especially from Karl Reese's archive. It seems like a bitter irony of fate that the Kuhnke Sport 1 proudly presents itself today as a DKW product, when the Auto Union Kurt Kuhnke had forbidden exactly that under threat of legal consequences. Nevertheless, you have to see it positively, because it was only the sparkling clean and beautifully designed Herz'sche renovation that caused a sensation in the professional world. Kuhnke's "work tool" would have been more of a wallflower, and our book would probably never have been written.
Another comment out of the book:
This motorcycle, owned by Audi Tradition, is doubtless based on the original ,Kuhnke Sport KS1'.This is historically proven. In 1990, the Lampertheimer DKW-collector and restorer Hermann Herz had the engine redesigned by the TU Darmstadt as part of a student thesis and redesigned the motorcycle based on the full image of the DKW US250-prewar-factory-racers. The ,restoration-result' looks pretty as a museum-masterpiece, but hardly remembers the historical proved KS1.
What happened, may have caused on the prevailing opinion on the term restoration on those days:
Functional and optical better than new! To keep the patina and originality wasn't really the theme. It was not until the ,Charta of Torino' 2013, that this conception was overcome.
Sadly, I don't own this brilliantly book. But this puzzle by 'sichel' encourages me to buy and read this book. Thank you for the puzzle, 'sichel'! Perfect! I only knew about the DKW-Prüßing-opposed-piston-engine out of a book, which also provided the K.-H. Meller-information. See picture attached
I also added a picture showing the 'Audi-Tradition KS1' (left) in comparison to the original bike on the right side
And the cover of the book (showing the original KS1)
Really exciting puzzle! Thank you once more!
Some more to Picture 3: Engine 'restored' by TH Darmstadt in 1990. Project management: Prof. Dipl. ing. B. Breuer. Leader in charge of the work: Dr. Ing. J. Präckel:
Complete new engine-block, new casted pistons and cylinders, new crankshaft, and new mechanical compressor.
Two more pictures
fromwien, there is not much more to add to your explanations, here is your next point.
August Prüßing was not a friend of the opposed piston design, this design was too elaborate for him. GS 250 and GS 350 were created on the orders of the Soviet authorities. There counter-piston engines were well known, e.g. as two-stroke diesel engines for locomotives.
Picture 1: the complete bike, picture 2: Siegfried Wünsche during a test drive on the motorway near Chemnitz.
Picture 3: KS 1 from the right, picture 4: Kurt Kuhnke on KS 1.
And now the "DKW-Counterpart". The design has no historical precedent.
Picture 5: Siegfried Wünsche, 1990, Test-drive on the Isle of Man. The demonstration ride in front of an audience fell through, bad weather.
The work on the TH Darmstadt: Due to corrosion, a new motor housing had to be made, material: aluminium instead of magnesium
Picture 6: Old housing with large corosion
Crank drive: Connecting rod and hub discs could still be used, changeover to the latest rolling bearing technology, use of rotary shaft seals.
Cylinders: Conversion from grey cast iron to nikasil-coated aluminium cylinders and new pistons with a special alloy, "Mahle 124".
Cooling system: The course of the cooling ducts was found to be not optimal, probably one cause of the overheating problems at Kuhnke, and was extensively remodelled.
Supercharger: The Centric-supercharger, not Roots!, could be used again with renewed bearings. But gas and oil ducting in the distributor housing needed to be modified.
Picture 7: The engine on the test bench, picture 8: Full-load curves of performance and torque.
Thank you very much for puzzle and point! Learned a lot about this very special engine type. And will learn much more, as soon as I hold the ordered book in hands.
I only want to add, that the engine in the Kuhnke Sport KS1 sits longitudinal in the frame. In the 'soviet'-ordered GS (picture 1 and 2 in your last post) across the driving direction.. (P.S. it has been in my intention to puzzle the GS-cycle, but now that isn't necessary any more..)
The different installation position can be seen in the pictures.