B U S I N E S S
P R O D U C T S
P R O J E C T S
P R O C E S S E S
B O U L E V A R D
ugo Junkers’ aircraft engines are to
this day the most efficient diesel en-
gines ever built. The creator of the
Junkers 52 (“Auntie Ju”), a flying legend, was
the first to recognize the potential inherent in
the opposed-piston principle – and this was at
the end of the nineteenth century. With its
pistons at opposite ends of a common crank-
shaft, the one controlling the inlet of fresh air,
the other the exhaust of the combustion gases,
it’s the only two-stroke cycle that easily out-
performs the present-day four-stroke cycle.
And so the specifications of the famed
Junkers engines 205 and 207 of the 1930s are
sensational even by the standards applied to
today’s diesel engines. From 16.6 liters swept
volume the JUMO 207, for example, genera-
ted 2,200 horsepower, i.e. 133 horsepower
from one liter – at only 3,300 revolutions per
minute. Owing to its simple design, consist-
ing of relatively few parts, it also had a unit
mass of 309 grams per horsepower and con-
sumed just 155 grams of fuel per horsepower
– advantages that still speak in favor of the
opposed-piston principle today. However, it
had one serious drawback: a high rate of wear
of the exhaust-side pistons, which necessitat-
ed short replacement intervals in the old air-
craft engines and which renders the principle
unsuitable for present-day car engines, pre-
cisely because of the high demands on their
longevity. This is not to even mention the
high pollutant emissions.
JUNKERS REVISITED
Notwithstanding, in the late 1990s, IVM
Automotive took up the idea again and
improved it using the tools and knowledge of
the present, to produce a one-cylinder engine
which impressed the engineering world at the
2002 Aachen Colloquium. Together with Die-
sel-Air, the aircraft engine specialists from
Dessau (Junkers’ hometown), IVM Automo-
tive succeeded in completely overcoming the
weaknesses of the old opposed-piston engine
using advanced development, manufacturing
and materials technology. In the meantime
two two-cylinder working prototypes have
been built of the so-called GKM 1200: each
displaces about 1,200 cubic centimeters and
develops 70 kW output with 250 Newton
meters torque (illustration). The distinctive
and decisive features of these joint develop-
H
OPPOSED-PISTON ENGINE
Increasingly lower costs, consumption, exhaust emissions
and weight – these are the most important goals of manufacturers as they continue to de-
velop the internal combustion engine. Employing the well-known opposed-piston principle
but brand-new technology, IVM Automotive has built a two-cylinder engine which promises
big reductions in all the above values.
CARBON-ALUMI-
NUM PISTON
With a 25 percent lower mass
and 300 percent higher tempe-
rature resistance than conven-
tional pistons, the carbon-alu-
minum pistons are the ideal
partners in the GKM 1200.
Junkers for Asia
16
