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Nitro
Engine Basics
Nitro
engines run on a highly
combustible mixture of methanol,
nitro methane (CH3NO2)
and castor or synthetic oil.
Rather than using spark plugs,
such as in typical 4-cycle
engines, these engines use a
method of combustion similar to
diesel engines (granted diesels
are generally 4-stroke).
Using
electrical current and a glow
plug, a hot spot is created in the
combustion chamber. This, in
addition to the compression of the
moving piston, creates the
combustion cycle. Within
seconds, the combustion chamber
and glow plug become extremely hot
and maintain subsequent combustion
without the need for the
electrical "jump
start". This is
what is often referred to as
"dieseling". The
only thing that breaks this cycle
is either lack of oxygen or fuel
(or an un-timely death of the
engine).
Nitro-Methane
Content
Fuels
are rated by their nitro-methane
content, typically 10-40%.
The higher the nitro-methane, the
more power to the engine.
Typically in 1/10 scale cars (with
.12 engines), 10-20% is plenty
sufficient. More than that
on these smaller scale cars will
go wasted, since the engines to
not efficiently convert use the
extra-potent fuel and the hookup
(traction) is usually marginal, at
best. They heavier 1/8 scale
and larger cars can see
significant increases in usable
power by using these higher (30%
and higher) nitro-methane ratings
In-Fuel
Lubricants
These engines do not use any
auxiliary method of
lubrication. Instead,
they use the same method of
lubrication found in most other
2-cycle engines. Because of
the physics of 2-cycle engines,
the fuel passes both sides of the
piston, including the
crankcase. This allows a
convenient method of
lubrication. By actually
combining the lubricants with the
fuel, you can continually coat all
the moving parts of the engine as
the fuel makes its way to the
combustion chamber.
Whatever lubricants are not
absorbed by the metal they come in
contact with are either burned in
the combustion chamber or are
discharged through the exhaust
port. This is why you
will often see these broken down
oils seeping from the mufflers or
tuned pipes. It is
just the normal process of cycling
through the lubricants.
Most
nitro-engine manufacturers
recommend using a special
"break-in" fuel which
contain a higher percentage of
lubricants for the first few dozen
tanks or so. This is to
insure that the engine has plenty
of lubrication in order to
properly break in and maintain a
good seal in the combustion
chamber.
This
is also why we encourage users to
tune their engines slightly rich
(see Engine Tuning &
Maintenance) so that there is a
sufficient supply of these
lubricants to the
engine. Although running
your engine lean may increase
performance (temporarily anyways),
it will be short lived if the
engine doesn't have enough
lubricant to maintain proper
engine temperatures.
After-Run
Lubricants
An important and often, overlooked
procedure in maintaining your
engine is after-run
lubrication. The benefits
from this are two-fold.
First, as the engine cools after
being run, moisture can build up
inside the engine, causing
corrosion. The next time it
is run, the engine will typically
see some undue wear from the
corrosion buildup. Secondly,
the lubrication process often
enhances the starting ability by
providing a better piston to
cylinder seal. Until the
engine has had a chance to warm
up, this seal is often sloppy, and
just like the engine in your real
car, a majority of the engine wear
happens in the first few seconds
before the lubricants in the fuel
get a chance to recoat the
engine's working
parts. You can find
these "after-run"
lubricants in your hobby
store. Usually a few drops
down the glow-plug hole or in the
carburetor right after you have
run your car can significantly add
life to your engine.
I
cannot stress enough how important
this is. Just like running
your engine rich is important for
your engine's life, so is this
simple process. Don't
let this one go unchecked.
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