18 • NITRO SLASH
DANGER! Model engine fuel
is poisonous to humans
and animals. Drinking the
fuel can cause blindness
and death. Handle with
care and respect. Keep
it out of reach of small
children at all times! While
driving, do not leave your
fuel dispensing bottle on
the ground where a child
could have access to it.
Follow fuel label warnings.
THE FUEL
Use the Right Fuel
It’s imperative that you use the correct fuel in your
TRX 3.3 Racing Engine for maximum performance
and engine life. Traxxas Top Fuel
®
Power
Plus
™
should be used to ensure correct engine
lubrication, performance, and ease of tuning.
• Top Fuel is the only fuel which is
100% certified for use in Traxxas engines.
• Traxxas Top Fuel is made with just the right
balance of natural and synthetic lubricants to
allow excellent throttle response and the best top-end performance,
without sacrificing long-term durability.
You may use 10%, 20% or 33% nitro-content fuel. Try to use the same
percentage all the time, avoid switching back and forth between fuels.
We recommend that if you break-in your engine on 20% fuel that
you stick with that percentage. If you do move to a higher or lower
percentage, make sure you readjust your fuel mixture to compensate
(see below).
Choosing a Nitro Percentage
A commonly asked question is “what is the difference between 10%,
20%, and 33% fuels?” Increasing the nitro in the fuel is almost like adding
extra oxygen to the combustion process. It burns more efficiently,
improves combustion, and delivers more power. When increased nitro
is used, more of the other fuel components are then required inside the
combustion chamber to maintain the perfect air/fuel ratio. Therefore,
overall fuel mixtures need to be richened slightly (on the high-speed
needle, about 3/4 of a turn counterclockwise when changing from 20%
to 33%, about 1/2 of a turn counterclockwise when changing from 10%
to 20%). This allows greater fuel flow through the engine and promotes
cooler running, even at the maximum lean settings.
If 33% improves power, then it seems that the highest nitro content
available (beyond 33%) should always be used in the engine. In reality,
there are practical limitations. Engines are designed to run best within
a range of nitro percentages. How the engine is ported, the size of the
combustion chamber and other factors determine how much nitro can
be efficiently used in the engine. The TRX 3.3 Racing Engine responds
exceptionally well to a maximum of 33% nitro, returning cooler temps,
more power, and a smoother throttle response. For those who want to
run higher nitro, 33% Top Fuel is the optimum nitro percentage for the
TRX 3.3 Racing Engine. Increasing the nitro beyond 33% can introduce
the need for engine modifications (ports, head shimming, etc.) to avoid
starting and tuning difficulties. There are limits to how much nitro an
engine can effectively use to make more power. Lower nitro percentages
have their own advantages. Nitro is an expensive component in the
fuel so 10% nitro blend is more economical for the sport user. 10% also
provides greater latitude with the needle settings for easier tuning.
When using Traxxas Top Fuel, using higher nitro percentages does not
cause the engine to wear out faster. 33% Top Fuel contains the same
quality lubrication package as 10 and 20% Top Fuel. Some non-Traxxas
high-percentage nitro racing fuels do sacrifice some lubrication in
attempts to increase performance. We urge you to not take chances with
your engine investment and use Top Fuel for consistent performance
and long engine life.
What about Other Fuels?
Can other brands of fuel be used besides Top Fuel? There are other fuels
that can provide satisfactory performance; however, there could be long-
term costs in the form of decreased engine performance, loss of tuning
ease, and shorter engine life. Only use fuels that contain both castor and
synthetic oil.
Everyone has an opinion or a claim to make about fuel. The engineering
team at Traxxas has spent years developing TRX Racing Engines. No one
knows more about the specific fuel requirements of Traxxas engines than
Traxxas engineers. We strongly urge you not to take chances with your
engine investment and use the Traxxas fuel made for the TRX 3.3 Racing
Engine.
Handling the Fuel
•
Follow all directions and warnings on the fuel can.
• Keep the fuel tightly capped at all times. Some components in the fuel
can evaporate very quickly and upset the balance of the fuel.
• Do not store unused fuel in the fuel dispenser. Immediately return fresh
unused fuel back into the fuel can.
• Do not mix old and new fuel. Never mix different fuel brands together.
• Store the fuel in a cool, dry location, away from any source of heat,
ignition, or combustion.
• Read and follow the safety precautions on page 4 in this manual.
THE TRX 3.3 RACING ENGINE
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