Bensa - Diesel väittelyyn:

Paul Rosche kirjoitti:

Tässä muutamia keräämiäni pointteja.

Myös seuraavan linkin kautta pääset 'Topicsin'
kautta, valitsemalla 'The philosophy of engine
design':in ja sen jälkeen 'interview':n lukemaan
pointteja puolesta ja vastaan. Ja varmasti
päteviltä kavereilta. Keskustelu on hieman
yksinkertaistettu jotta maallikotkin ymmärtäisi,
mutta yhtä kaikki hyvää tietoa.

http://www.bmwgroup.com/e/index2.shtml?s80&0_0_www
_bmwgroup_com/7_innovation/7_2_aid/aid_home.shtml&


"No charging and no turbos: the secret of M Power
is high-revving, naturally aspirated engines. For
over 20 years BMW M has been true to this
principle. It is technology which is also applied
to Formula One racing: High engine speeds in
conjunction with respective gear ratios generate
maximum thrust. The new M3 exemplifies the thrill
of this principle, exploiting an enormous engine
speed range: from 1000 to 8000 rpm.
An added plus: the size and total weight of the
engine can be kept to a minimum.

In the course of time BMW M has consistently fine-
tuned the technology involved. Exclusive
materials and especially light components make it
possible to extract more and more output from
every cubic centimetre capacity."

-BMW M


"Most of us are familiar with high revs from
Formula 1. High revs are basically a good thing
because when they're combined with the right
transmission, the maximum thrust can be achieved.

It's a question of how the engine power and the
potential revs can be converted most effectively
and efficiently. It's rather like riding a
mountain bike: in a low gear and with a high
cadence you're in a better position to manage a
gradient with less exertion than if you use a
higher gear with a lower cadence. Therefore the
decisive factor is not just the maximum torque in
Newton metres as measured on the test-bed: a high
engine speed combined with the right transmission
enables more power to be brought onto the road
despite the lower torque.

we don't design engines with a view to achieving
the highest possible final speed, but instead we
focus on direct response, high thrust and
acceleration. After all, it's the acceleration
that you feel - caused by the high revs with the
optimum transmission system.

In principle, high-revving engines have one major
advantage over engines with turbochargers: they
respond much more quickly. There used to be the
problem with turbochargers that because the
exhaust turbine was revving fast as well in the
high-revs range, it was compressing the air more
than was actually necessary. On the other hand,
in the lower revs range, the turbocharger was not
supplying the power needed and so the air was not
being compressed enough.

In the meantime, though, turbocharger engineering
has come a very long way.

However, here you have to bear in mind that
diesel engines are less suitable for high revs
due to the limited combustion rate. But in our
opinion these principles don't really make any
sense for a sports engine. The motor and its
components have to be designed with relatively
large dimensions in order to withstand the forces
that arise. However, in this case large also
means comparatively sluggish. And apart from
that, as I've already said, which concept you
choose is also a matter of philosophy. I find
that the approach we're taking at BMW M is the
more for the sports enthusiast and the purist.
The power comes from the engine itself and is
exploited to the full. Very directly, without any
additional components such as a turbocharger for
example. And without any sluggishness - it
couldn't be more spontaneous."

-Gerhard Richter, engineer and head of
development at BMW M.


"The advantages of this concept are plain to see:
high driving performance figures can be achieved
with engines, axles and drive systems of
relatively small dimensions. And all that too
with comparatively little consumption and low
emissions. "

-Hans Heiland, director of tachnological
communication at BMW

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