News
Get the latest Rc Car News Here
Nitro Powered RC Cars
- Nitro RC cars are named for the special type of fuel that gives them and their
motors such kick. Though not the best choice for beginners, they are the choice if
speed and power are what you want from your RC. The great popularity of nitro
RC cars and trucks is due not only to their speed, but is also because of the
realism they offer—sights (smoke), sounds (tuned pipe) and smells (exhaust) just
like the real thing! Over the last several years, the quality of nitro RC’s has been
greatly improved, making them safer and more reliable than in the past.
There are four defining features of a nitro RC car:
• special nitro fuel
• high horsepower nitro engine
• tuned exhaust pipe
• Realistic, replaceable air filter.
Two different power sources are required for a nitro RC car, starting with battery
packs for the transmitter and receiver. The car itself, as the name suggests, really
does use a nitro methane fuel, much like a real top fuel drag car uses.
There are two kinds of nitro motors: the 2-stroke and the 4 stroke engine. The
more popular 2-stroke engine is similar to the kind of engine found inside motocross
motorcycles, chain saws and weed whackers. This type of engine has no separate
oil reservoirs, so the oil that lubricates it is included in the fuel mixture.
Conversely, the less popular 4-stroke engine does have an oil reservoir and
therefore depends less on a gasoline/oil fuel mixture for lubrication. When
running or racing, the car’s fuel tank will need refilling every 5 to 10 minutes
Nitro Engines: 2-Stroke
The 2-stroke is the engine most commonly found in nitro RC’s. “Stroke� is meant
by the number of times the piston travels through the engine sleeve in the
combustion chamber. 2-stroke engines produce power in one cycle, which is
divided into the two “strokes.� The piston has two positions: top dead center where
the cycle begins and ends, and bottom dead center, which is the middle
point of the power cycle. Combustion causes increased pressure in the chamber
and forces the piston down. As this occurs, the exhaust ports are opened so gases
can escape through the manifold. The second stroke begins when the piston
reaches bottom dead center and the crankcase and then moves back up the
engine sleeve. This causes the pressure to build up again as the piston
approaches TDC once again, completing the power cycle. The next stroke occurs
as soon as combustion from the glow plug sparks it again.
Nitro Engines: 4-Stroke
Less common but more powerful, 4-stroke engines are more like what you’ll find
under the hood of your real car or your lawnmower. Though similar to a 2-
stroke, a 4-stroke engine has 2 full cycles with 2 strokes of the piston each (for a
total of 4 strokes). Unlike the simpler glow-plug ignition that a 2-stroke uses, a
4-stroke regulates the air and fuel in the chamber with a geared cam mechanism.
Intake timing is how much and when this air/fuel mixture enters the cylinder,
while exhaust timing refers to the escape of hot gas from the cylinder.
The easiest way to understand what happens in the 4-stroke power cycle is
imagine the 2-stroke cycle simply stretched out to get the most out of each
segment of the piston’s movement. The piston begins at TDC and as it travels
down the cylinder the geared cam allows fuel and air into the combustion
chamber.
The intake valve closes when the piston reaches the bottom of the cylinder, which
is then forced back up by the flywheel and drive train components. This
compresses the air and fuel, and the pressure causes combustion as the piston
reaches the top of the cylinder again, completing what is referred to as the
compression stroke.
As the fuel mixture ignites it initiate the so-called combustion-stroke, during
which the piston travels back down the cylinder and up again. In the final “power�
stroke the gases are forced out to the exhaust systems—just as in the 2- stroke engine.
The cycle is then repeated.
4-stroke engines rely on intake and exhaust valves to complete their power cycle.
This is combined with a number of other features—a moving crankshaft, several
valve-train components, camshaft, rod and pistons and the geared cam
mechanism—to make a more powerful, but more advanced engine. The
improved management of fuel and air flow in and out of the engine makes the 4-
stroke more efficient, though their advanced mechanisms mean they require
meticulous attention and maintenance.
You’ll need a starter for the engine, of which there are two types:
• a pull-start nitro engine (these use a process like your lawnmower to
start)
• Or a non-pull nitro engine (these fire up with a starter box).
The pull start nitro engines cost a little more, but you don't have to buy a starter
box and it's less you have to carry around to run your vehicle. Just take it out, pull
on the starter, and you're ready to go! Be sure to check your instructions to
choose a starter that’s right for your car.
To keep your nitro RC running at its best, constant maintenance is necessary.
This includes keeping the engine clean and well-tuned, setting it up correctly and
using good clean fuel. As well, if you’re running your RC off-road, you’ll need to
make certain it is properly cleaned after you run it, otherwise dirt and grit can
slow down or even ruin your engine. Any special procedures particular to your
car will be outlined in your owner’s manual. Remember that your engine will
only run as well as you treat it—so take great care of it, and you’ll never have
trouble on race day.
Fuelling Your Nitro RC Car
Nitro RC cars run on a blended fuel easily available at local hobby shops or
online. It is made up of a blend of methyl alcohol (methanol), nitro-methane
(nitro), and oil. In order to understand how nitro fuel work, you need to know
what each of these three components does for the car:
• Methanol provides the main power to the engine and is the main
ingredient in model fuel. It has an ignition point that allows it to be
ignited with the kinds of platinum-element glow plugs used in RC engines,
and it releases more energy per pound of air than gasoline. Because it’s easy to
get, it’s not expensive—you’ll find model fuel much more reasonably priced than
regular gas.
• Nitro-methane is added to assist the idle and acceleration and to enhance
power output. Nitro is referred to as a “hot fuel,� and is only used in small
amounts in model fuels. It can be explosive if not handled correctly, so
take care to read the fuel tips offered here, and always follow the
manufacturer’s instructions when filling up your RC.
• Oil is need as a source of lubricant for all the moving parts in the engine.
Here 2-stroke and 4-stroke engines will require different fuels, since 2-
stroke engines have no separate oil reservoir, and need oil mixed in with
their fuel. There are two types of oil found in model fuels- castor oil and
synthetic oil. These can be used by themselves or in a blend, with
synthetics being far more common these days. This is mainly because
synthetics are cheaper and less gummy than castor oil, which used to be
the only oil used. For some engines, a blend with a large percentage of castor
oil may work best, since it is actually a better lubricant at higher
temperatures. The synthetics are far less messy, however, and leave less
gum on your engine. You’ll be able to choose from blends of synthetic and
castor oil that vary in their percentages- try out a few to find one that runs
your engine best.
RC fuel blends are expressed in percentages based on the amount of each
component ingredient used, and of course the one right for you will depend
greatly on your car and engine. Most model fuels contain mainly methanol, to
which about 20-22% oil and 10-15% nitro is added. Be sure to check your owner’s
manual for suggestions and guidelines about which blend is correct. Bear in
mind that you may have to try out a couple of different types and blends before
you find the one that’s right for the way your engine is tuned. And if your engine
isn’t running properly, one of the first things you should do is change the fuel.
Taking proper care of your nitro car’s fuel is extremely important. Not only will it
help your car run better and make for less wear on the engine, model fuels are
flammable and could be dangerous if not properly stored.
• Nitro fuel should not be stored in unsealed containers.
Because methanol mixes easily with water, the container you store it in
should be completely air tight. Otherwise, air could get in and evaporation
or condensation could occur, ruining the fuel. It will cause your engine to
run too hot and be quite damaging to your car’s fuel and exhaust systems.
• Store your fuel at room temperature, and at a constant temperature.
Again, you want to avoid any air in your container or in the fuel, which
temperature swings can cause to condense. Do not store your model fuel
in a room that varies widely from hot to cold or vice versa.
• Keep model fuel away from light.
Nitro methane degrades in light, which means you need to store your
model fuel in a cool, dark place. If you leave it exposed to sunlight or store
it in a brightly lit place, the nitro will degrade completely, as though it
hadn’t even been added to the fuel in the first place. This will cause your
engine to run very poorly, or cause poor starts or stalling.
• Do not store fuel more than a year.
In addition to following all these steps, you must also replace your model
fuel frequently. Though proper storage will keep your fuel fresh and
running clean, it cannot be stored for years and years. Most
manufacturers offer some guarantees on their fuel, but these will not apply
if you have stored it for an extended period of time. Most importantly, old
fuel can be dangerous, so don’t leave it stored indefinitely.
Nitro Maintenance and Tuning
So now that you know what’s under the hood of your RC, there are few more tips
that will help your car run better:
! Improve your acceleration by proper preparation of your clutch.
Over time, a glaze can form on the clutch and the clutch bell, which causes
the car’s acceleration to noticeably decrease. Scuffing both the clutch
shoes and the clutch bell with fine-grit sandpaper or steel wool and a good
cleaning with motor-spray will remove this glaze, and prevent the clutch
from slipping against the clutch bell.
! Extend the life of your car’s differential by breaking your motor in gently.
Your car’s differential filled with small, complicated gears that make them
both complicated and expensive. This is not a part you want to replace
frequently, but carefully breaking in your car before racing or running it
full out can greatly extend the differential’s lifespan. To break in your
engine, run it at ¼ power a few inches off the ground, and then run some
slow, steadily powered figure-8’s. This should set the gears in the
differential and you can run it full out without damaging the engine. Make sure you
keep your header in position.
Your car’s header is attached with a tiny spring, meaning it comes off very
easily if you hit something or if your car gets hit by something. If you’re
racing, this can be a huge problem to put back on in a hurry, so be sure to
attach your header to the engine block more firmly using a small piece of
safety wire. Make sure you twist the wire firmly around the header and be
sure to cut off any excess.
! Brace your air filter to prevent losing or damaging it.
The small piece of the same safety wire that secures your header should
also be used brace your filter. Again, twist it tightly to prevent the filter
from becoming loose and remove any excess.
! Protect your pull-start cord from fraying and breaking.
Over time, the cord of a pull-start engine can often become worn and
frayed. This can be prevented by covering the edges of the opening- try
duct tape or cutting up a small section of fuel tubing. Make sure not to
obstruct the opening, but rather create a smoother edge to the opening for
the cord get in and out of with out fraying. Never leave your pull start cord
pulled all the way out- if this happens, it could get stiff or be impossible to
reinsert
! Follow your manufacturer’s instructions for the best results.
Your car will come with complete instructions and owner’s manual, which
you should read carefully for all specifications and any technical issues you
have with your RC. Should you run into something you can’t fix or an
engine that simply won’t run properly (or at all!), it’s best to consult your
local hobby shop for some expert advice and help.
There’s nothing like the realistic roar and smoke of a nitro RC, which are fast
powerful enough to make for some exciting races. Bear in mind however, that
nitro cars and the engines that power them are very complex, and as such require
frequent tuning and meticulous care—much more so than an electric RC.
Because of greater complexity, you will also find they tend to be more expensive,
as well. What this means to you as a driver is that you need to decide in advance
what your budget is and just how experienced you are with engines and RC
racing.
If you’re beginner but you still have your heart set on a nitro car, they can be
purchased in ready to run versions that will get you in the race as soon as you
open the box. Although these still require the same ongoing attention and
maintenance, you will be saved the initial trouble of building the car from
scratch.
Ready to run nitro cars and trucks are more expensive than the ones you build
yourself, but they’re far easier if you’re still unsure about your mechanic ability.
Also, since even ready to run kits contain complete instructions on how they go
together, you can rest assured you’ll be able repair, maintain and add on to your
car for a long time to come.
The main attraction of nitro RC cars is their realism and their power—they’re
fast, they roar and they smoke—just like real cars! They can be tuned to reach
speeds up to 60 mph and they can race as long as you keep filling the gas tank.
Though not recommended for complete newcomers to RC racing, nitro RC’s are
by far the most popular.
top