Vintage Thing No. 13 - the DKW two stroke triple

The cutaway gives any idea of how few moving parts the GKW engine had. It had 3 coils through

Following VT 10 about the Mercedes-Wartburg, I tried to find some more information about the DKW engine that was the basis of the Wartburg motor. The Deek also sired the early Saab and Auto-Union two-strokes.

There's still quite a following for these little cars. Wartburg's and Trabants have a kind of retro-Commie Cool but I couldn't find the technical info I was after.

However, in the course of my latest investigations into Trojan engines, I found a slim volume in the Anarchadia Publishing research library, entitled The Two-Stroke Engine (bit of a give away, that) by K G Draper, published by Foulis. Not only did it have a schematic diagram of the Trojan engine but also a cut away of the little Deek - DKW stands for Das Kleine Wunder, the little wonder.

You can clearly see the seven moving parts - 3 pistons, 3 conrods and a crankshaft.

This elegant design was first introduced in 1939 with 70mm x 78mm bore and stroke and 900cc, giving 28kW (38bhp) running on the "petroil" oil and petrol mix beloved of stroker stokers everywhere.

Aero styling was quick to catch on in countries with autobahns

DKW had used two stroke twins for many years previously and the new F9 featured highly aerodynamic bodywork designed by Guenther Mickwausch. A Cd of 0.42 gave this car a top whack of 68mph.

The company was effectively split in two by the post war partition of Germany and parallel developments continued on either side of the Iron Curtain. In the west, post war Deeks were 71mm x 76mm and 896cc. A freewheel was also provided to prevent the engine seizing on long hill descents when the petroil mix was not guaranteed to reach those moving parts - all seven of them.

Clever packaging for its time

There was no water pump as cooling worked on the thermo-siphon principle and involved a big radiator perched behind the engine over the gearbox. The 1953 DKW F-91 Sonderklasse made a practical family saloon that could do 75mph on the Autobahn and coupes, convertibles and estate cars were also offered. A 741cc Junior version (68mm x 68mm) ousted the smaller twins that carried on into the post war period and this smaller engine hatched the early SAAB two stroke turkeys.

By the late fifties, Deeks had a bore and stroke of 74mm x 76mm to give a capacity of 980cc. The single carburettor was were either a Solex or a Bing depending on the model. DKW's most powerful production spec gave an output of 41kW or 55bhp @ 4500rpm, and with a smoothness equal to a four stroke six cylinder engine. Some Deeks were even called "3=6" to drive the point home but while the illusion of smoothness probably worked, the purple haze of the two stroke fug travelling behind them undermined the glamorous aspirations somewhat.

In the parallel universe of East Germany, the Wartburg grew up to produce 37kW or 50bhp at 4250rpm from 73.5mm x 78mm and 992cc. Wartburgs, known as IFAs or AWEs in their homeland initially resembled the pre-war DKWs as penned by Herr Mickwausch but in 1954 adopted a frankly American style.

German looks yet strangely American (until you started it up)

DKWs kept a degree of the Mickwausch line until 1964. They were quite roomy for a 1-litre saloon. All were front wheel drive and had "three on the tree" - three forward speeds with a column change.

The DKW gradually morphed into the Audi after a phase as Auto-Union. In fact the in line engine ahead of the front wheels became something of an Audi tradition. The 1964 DKW F-102 shared a boxy bodyshell with the contemporary four pot four stroke Audi 60. Mercedes-Benz engineering supremo Rudi Uhlenhaut oversaw the development of this ultimate DKW stroker. By now it had four speeds - still on the steering column - 81mm x 76mm bore and stroke and 1175cc. It put out 45kW or 60bhp and weighed 900kg, roughly the same as its pre-war ancestor, which was enough for a Hochgeschwindigheit of 84mph, about what its cousin the boxy Wartburg 353 would do.

But Mr Draper in his treatise on The Two-Stroke Engine has this to say about the Deek 3 cylinder.

"Latterly, supercharged engines have disappeared from the International scene and some success has been achieved in recent years by the 1 litre three-cylinder DKW fitted in Elva and Lotus cars for Formula Junior. Gerhard Mitter and others have doen excellent work on these engines and though precise details are naturally not fully disclosed, it is known that the engines are bored out to 1080cc, special pistons are used, the compression ratio is raised to 9.6:1 and the combustion chambers polished. Ports are also modified and a great deal of research has been done on tuning the exhaust and induction systems. On most of these engines the mixture is supplied from a cluster of 35mm dell'Orto carburettors fed by two float chambers. Each sparking plug has its own ignition coil and the contact-breaker is driven from the nose of the crankshaft. The tuned engines gave approximately 82bhp @ 5500 rpm and also a comparatively high torque lower down in the speed range. The later Mark II Elva Auto-Union engines were prepared by the Rytune Engineerin Company of Winchelsea, Sussex, and were fitted with three Amal carburettors. To see and hear these Elva cars in action was a new experience in motor racing, the absence of mechanical clatter being most impressive."