18 • NITRO 4-TEC 3.3
DANGER! Model engine fuel
is poisonous to humans
and animals. Drinking the
fuel can cause blindness
and death. Handle with
care and respect. Keep
fuel 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
®
should be used to
ensure correct engine lubrication, performance, and
ease of tuning. Traxxas Top Fuel has been proven in
thousands of engines, so you can count on it every
day for great performance.
• 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 the highest
grade natural and synthetic lubricants to allow excellent throttle
response and the best top-end performance, without sacrificing
long-term durability.
• All of the components in the fuel are carefully selected from the
best materials available and then custom blended to match the
metallurgy and temperature characteristics of Traxxas engines.
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
