Die vor der Tankstelle

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Purchasing classics there

We're going to talk about the last mass-produced Western European two-stroke car, the 102 DKW F1963. I did a search on the used and classic sites. At the time of writing this piece, there is exactly one for sale in the entire European Union. And it's not even that expensive. You can get it for 15.000 euros. That is considerably less than its DKW congeners in the same condition. The F102 was a worry child. And that wasn't because of its basic design.

Born as baby Benz

The DKW F102 was based on a new, small model from Mercedes, a major shareholder in Auto Union. For marketing reasons it eventually became a DKW, because that is where the customers for the small middle class could be found. A Mercedes star on a smaller car could also hurt sales of the higher and luxury class Mercedes. For example, it was decided in Stuttgart to award the bodywork to DKW, for which the well-known three-cylinder two-stroke was enlarged and adapted. And that's where the shoe started to wring.

There was nothing wrong with the DKW three-cylinder two-stroke. It debuted in 1950 in the IFA F-9, simultaneously in the DKW F-91 Sonderklasse and later in the 3 DKW 6=1955, the Auto Union 1000 and the 'mini-Thunderbird' 1000Sp. Saab also used this engine in the 93, 96 and Sonnett. It was in similar configurations in all Wartburg models, the Melkus 1000 Sport and the Barkas vans. It was a millions of times built, very reliable engine. Anyone who laughs at a two-stroke Wartburg should be referred to the renowned Saab and Auto-Union.

A little bit of two-stroke knowledge

A two-stroke reverse-purge engine, despite its simple construction, is a very clever design. Unlike the four-stroke engine, which acts as a positive displacement pump, combustion chamber filling depends entirely on the placement and shape of the purge and exhaust ports. Fresh air with oil and petrol vapor is forced crosswise into the combustion chamber via the purge ports and the combustion gas is pushed away, while of course as little combustion gas as possible may remain behind and at the same time as little fresh mixture as possible may disappear into the exhaust ports. And that from stationary to maximum speed and at both low and extreme loads. That is why a two-stroke stationary, so no load, does not run very well. But once it gets going, it's a beautiful engine, short on the throttle, wonderfully bright, capable of making a lot of revs and delivering power. The three-cylinder two-stroke has seven moving parts, plus a water pump. Simplicity graces the engine.

Of course, the two-stroke has its limitations. First of all, no pressure lubrication is possible; the engine oil is supplied with the gasoline vapor mixture, condenses in the lower crankcase and must find its way through lubrication grooves to the crankshaft and connecting rod bearings. Despite a double number of power strokes, the efficiency is not twice that of a four-stroke, but about 1,6 times. And the maximum displacement is about 350cc per cylinder.

Who wants the bottom of the can…

And DKW sinned against that last rule with its 1200cc engine from the F102: 400cc per cylinder was just too much. The result was a deterioration in efficiency in daily use. In practice, the fuel consumption rose from 1:7 on country roads to 1:6 in the city and 1:5 on fully loaded holiday trips in the Alps. You might as well go touring in a big V8. After a year, DKW came up with a solution: the accelerator pedal got an extra spring so that after a few centimeters it was much harder to accelerate. But if that helped...

And bad luck never comes alone. To avoid the infamous blue plume of smoke, a Bosch-developed lubricator was installed, which debuted a year earlier in the Auto Union 1000S and Sp. This automatic transmission regulated the oil injection according to the load on the engine and also guaranteed lubrication on descents, but unfortunately in winter cold, the viscosity of the engine oil jeopardized the injection of engine oil. In such a case, the engine usually stalled at an uncomfortable distance from home. Few things are worse than being stranded by the road with a broken engine on a cold winter morning a kilometer from home. Numerous warranty cases were the result and DKW dealers preferred to disconnect the lubrication machine just to be safe and let the customer fill up with mixed lubrication again. Expensive mixture lubrication. The resale value plummeted, the customers walked away.

dkw F102 engine
DKW F102 with the three-cylinder two-stroke engine. Mixed lubrication requires powerful sparks, each spark plug has its own ignition coil and set of contact points.

Dark clouds over Ingolstadt

Two years after the introduction, customers switched en masse to a beautiful Ford Taunus 17m P5 with its V4 or silky smooth V6 engine or a beautiful Opel Rekord with the then very modern 1700S, 1900S or 2200S CIH engine, stronger and more economical at the same time. Auto Union decided to stop production. The dark clouds of bankruptcy gathered over Ingolstadt, partly because the 102s were a period of market saturation and therefore fierce competition. Ultimately, less than half of the F 55.000s produced would find a buyer. 102 F25.000 were made, XNUMX were sold. It looked like the Ford Edsel. One of Germany's oldest and most renowned car brands was in danger of disappearing.

Mercedes comes to the rescue

Daimler-Benz had a recently developed four-cylinder engine in the warehouse that soon had no other destination. It was the M118, a so-called 'medium pressure engine', so named because of a compression ratio of 1:11,7.

Normally such a high compression would cause a lot of knocking and burnt valves, but spiral inlet channels mixed the petrol vapor more intensively with air and the ignition only started when the spark plug ordered it. The engine was actually intended to run military vehicles on varying types of fuel, but there was no application for it. In practice an excellent alternative to the three-cylinder engine, were it not for the fact that there was no space under the hood for it – the gearbox with the drive shafts, which also contained the brake discs, were quite far forward. But it worked. The four-stroke was placed under a considerable slope and radiator moved to the side, the nose was slightly extended and voila, the Auto Union F103 was born. Because the brand name DKW, at least on this model, now had a notorious sound and to emphasize that it was a completely different car, the pre-war brand name Audi was taken from the stable. The new car entered the market from 1966 as Audi 60, Audi 75, Audi 80 and Audi Super 90, with the figures referring to the number of horsepower under the hood. The program was expanded in 1968 with the larger Audi 100, of which a beautiful Coupé version also appeared. In a few years, Auto-Union had shaken off the two-stroke smell and entered the upper middle class.

Audi F103
Mercedes M118 engine in the Audi F103. The engine block tilted, the radiator to the side.
Audi F103
Audi F103: models 60 / 75 / 80 / Super 90, 1966-1971


Engines

1966 did not mean the definitive end of the three-cylinder. The DKW Munga all-terrain vehicle was built until 1968, also because defense contracts were involved. Until that year, the Saab 96 could still be ordered with the two-stroke. And needless to say, the twin brother Wartburg continued to use this engine until 1990. Suzuki also used this three-cylinder two-stroke for a long time for export to third world countries. Loved for its simplicity.

Then there was a six-cylinder. The company Müller in Andernach developed a V6 based on two three-cylinder engines. It must have been quite an art to divide the lower sumps into six gas-tight compartments, but apparently it worked. This 1600 cc 'Müller-Andernachmotor' produced 80 hp and about 100 were built into a DKW F102

The Mercedes four-cylinder four-stroke medium-pressure engine was installed in the Audi 1968 from 100, with a cylinder capacity of 2 liters and 100 hp. Later, with an overhead, toothed belt-driven camshaft, it ended up in the Audi 80, the VW LT, the Porsche 914, the AMC Gremlin and served as the basis for many VW engines of the 70s. so thinks one must find something from Mercedes, must bear in mind that Audi probably would not have existed if Mercedes had not designed the body and engine of the first post-war Audis.

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17 comments

  1. De Munga, once learned to drive a car in the polders on the old, written-off bicycle cross track.,
    Up and down hills, up stairs, and drive across bends.
    The carts through grasslands.
    Thing was ex-defense, so 24 v, so trailers, etc. never plugged in.
    Pretty indestructible, beautiful.
    I was 11 years old . . ... . .
    Later read that the German armed forces took the intermediate shaft separately, and drove as a 2-wheel drive, to save the diffs (no intermediate diffs)
    In NL the axle had to go in, so diffen had a hard time.
    Mixing lube machine was also thrown loose in D.
    There is an “integrated” cup in the petrol filler cap to mix the correct amount of oil per 25 liters.
    In NL the mixing grease had to be fixed, so problems.

    My father now drives Audi from the first 100, and has driven them all up to the A6C6
    Now drive A4, and I now drive a 200 TQ myself and his old A6C6

    A kennsi does have a lot of hobby dkw's and ifa's

  2. That about the maximum cylinder capacity per piston sounds familiar to me. Have you ever heard that an internal combustion engine (don't remember whether it was 2,4 or both-stroke) is best off with a capacity of between 300 and 500cc per piston because it runs the most efficiently. That a two-stroke can handle a maximum of 350cc is a nice fact, but what about a two-stroke diesel? I can't imagine that a truck is equipped with an engine with a huge number of pistons to have a bit of swept volume. In addition: what about the bore/stroke ratio in a two-stroke petrol? I think it makes a lot of difference whether that 350cc per piston is packed in a short or long stroke.

    • Ard's trucks with a two-stroke diesel engine, as is common in America, do not have a reverse purge but a ring of inlet ports and one or more exhaust valves. They are therefore always turbo diesels. This also applies to the two-stroke marine diesels.

  3. DKW. Around 1965 my father bought a second-hand DKW 1000S. Diamond blue, white roof, four-door continuous rear window and no trim on the boot lid. Registration number: ET-39-20. Experienced everything and with four people packed full of mega tent to the Vosges. Had four years. In 1969 my father traded these in with the company De Rek, who did the Leidsevaart in Haarlem in DKW and Wartburg. Company still exists and they still own a DKW 1000 and a DKW Junior.
    The 'new' acquisition was an F102, teal, registration number: EZ-43-59. Also four-door. I remember the engine often boiling when we camped somewhere in Wales in 1972.
    In 1973 it was finished with the phenomenon DKW.
    My father also had a love/hate relationship with this brand. According to him, DKW also stood for: Dat Kreng Weigert. Then came a three-year-old Saab 99.
    Since my dad had a thing for cars, I have a nice series of photos of both DKWs from the sixties and early seventies.
    If the editors are interested in this, they know where to find me.

  4. A garage owner in Obdam had twice an Audi 100, with original registration from 1972. I thought they were interesting cars, but I expected them to bring in quite a bit of money.
    Until they were both gone.
    When I asked what had happened to them, the answer came that they had been sold to a car dismantling company, for -probably- next to nothing. In any case, he hadn't gotten much for it.
    Sorry to hear. Even though the Audis from those years (with the exception of the coupé) may not be worth much yet, they were interesting enough to be preserved.
    Unfortunately I do not know which company bought them, nevertheless I hope that they may have been discovered in time by an enthusiast and have not disappeared in the press.

  5. My parents and my grandparents drove an Audi 60 and 100 respectively at the time. The cars drove pleasantly, comfortably and quickly. They were also nicely finished but… sopping oil. They seemed to still have a two-stroke engine. The quality of the gearboxes was also poor. Never understood how Audi could grow into the brand it is today.

  6. Funny that the indestructible 2 liter engine from my VW LT28 was actually designed by Mercedes Benz. That also explains the later collaboration

  7. Thank you for pointing out errors. That's why I'm not a DKW / Auto Union specialist. For example, in the article I completely ignored the DKW Junior and the F11/F12, which also had the lubrication machine in their smaller engines (and the same problems, of course). Not to mention the three-cylinder two-strokes in the DKW Monza in the West and the Melkus RS1000 in the East.

    So keep correcting, because we all learn something from that.

    What stands as a house is that the DKW's cars were of the highest quality. That has been continued with Audi, and Daimler-Benz has given them a helping hand (or a big hand).

    DKW Monza

  8. Nice art. with some mistakes, my fam. 6 boys have all driven DKW auto-union. The mixing machine was there earlier than mentioned, an option perhaps? We even had a '35 two-cylinder, half wooden construction. DKW was an expensive car in its class, just like AUDI now. I have ridden div 3=6 and 1000 and 1000S types. The end of that period had various reasons, the fuel consumption started to play a role, the exhaust system was very expensive and did not last that long, and the bubbling was not popular. The handling was good and plenty of interior space. And with the original exhaust they were quiet.

  9. I agree with Jan Bonsema. I also learned a few things from it. So I was not aware of MB's involvement in Audi.
    Well done MB! Beautiful cars have come out of it!

  10. Hello

    never learned so much in a small piece, i.e. body was designed by MB, Saab
    had the DKW motor and no own design. Ditto max content per cylinder 350 cc and a few more things

    • And DKW was the two-stroke specialist. Their RT motorcycles have been endlessly copied. And there too you see that the single cylinders stopped at 250cc. Above that they will be twin cylinders.

      Their East German successors of MZ always made single-cylinders, also up to 250cc and from Czechoslovakia came the CZ or Jawa 250cc single-cylinder and the Jawa 350cc two-cylinder. Other engines derived from the DKW RT series were the BSA Bantam and the Harley Davidson Hummer, always with 175 cc single cylinders on board.

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