Re: [MV] Density Compensator F/U

From: Employee@MilVeh.com
Date: Sun May 25 2003 - 09:59:11 PDT


"There are a lot of myths floating around regarding
the Multifuel engine. I will try to help you. In the
late 1950's the decision was made to adapt the G742
series vehicles (as well as many other tactical
vehicles) to run on diesel or gasoline or various
other fuels. Fitting the Continental LDS-427
turbosupercharged, multifuel engine did this. This
engine built under license from M.A.N.
(Maschinenfabrik Augsburg-Nurnberg) uses the
Hypercycle combustion process.

Into the top of the piston of this engine is machined
a spherical combustion chamber. During operation the
injector sprays 95% of its charge onto the wall of
this chamber in the form of a thin film. The remaining
5% is atomized.

The compression stroke, which generates temperatures
in the 900-1000 degree range, ignites this atomized
charge, and the main portion of the charge is
gradually vaporized by an air swirl created during the
intake and compression strokes. Since the air swirl
removes only the top surface of the fuel sprayed on
the walls of this combustion chamber during the power
stroke combustion is even and there is no detonation
knock.

Unfortunately, the LDS-427 was not entirely
successful, and this led to the development of the
LD-465 series of engines. Whereas the LDS-427 was
turbo-supercharged, the LD-465 was a naturally
aspirated engine. If you ever convoy behind someone
driving a truck with one of these engines it is a
memorable experience, as there is a voluminous cloud
of black smoke at virtually all speeds. It is this
smoke cloud that led to the development of
the LDT-465-1.

While the LDS-465 version of this engine was from the
beginning turbosupercharged (as well as other internal
changes) for additional power and used in 5-ton
trucks, the turbosupercharger on the LDT was applied
to
reduce this exhaust plume. The LDT-465 produces only 4
horsepower more than the LD-465, but the power comes
on quicker, and the exhaust plume is not as
pronounced.

At this point I will mention that I have seen it said
in various books and articles that the LDS-427 were
multifuel engines, but the LDT-465 series were not
multifuel engines. I have not been able to find any
information to support these statements. The nameplate
on the engines say "Multifuel," both series were
produced under the M.A.N. license, the Technical
Manuals all say "multifuel," and the block, head, and
piston designs are essentially the same. Therefore I
believe both the LDS-427 and LDT-465 series to be
Multifuel engines.

The injection pumps on all of these engines except the
early LDS-427 were originally equipped with a fuel
density compensator, which varies the fuel delivery
rate as fuels are changed or mixed. As built, no
adjustments are changes are necessary to change fuels,
and mixing of various fuels is permissible.

In recent years, the fuel density compensators have
been bypassed, and they are now tagged "diesel fuel
only," but instructions are included to
reconnect the compensator.

In practical terms, it is generally considered unwise
to operate these engines on gasoline, and under no
circumstances is av-gas permitted.

I have burned diesel, kerosene, and Jet A in my trucks
at various times, and can note no difference in engine
or vehicle performance.

Hope this helps,
David Doyle"



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