14 • T-MAXX 3.3 OWNER’S MANUAL
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.
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.
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.
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 3 in this manual.
FILLING THE FUEL TANK
Use the included fuel dispensing bottle
(Traxxas Top Fueler, part #5001) to put
fuel into the T-Maxx’s fuel tank. To fill the fuel bottle,
squeeze the air out, insert the dispenser tip into the
fuel can, and release your grip on the bottle. As the
bottle expands, fuel will be drawn into it.
To fill your model flip up the spring-loaded
cap on the fuel tank, insert the tip of the
fuel bottle, and squeeze to
dispense the fuel. Fill the tank
until the fuel level reaches the
base of the filler neck. Close
the fuel tank lid, making sure
it closes tightly.
Fuel Tank Seal Adjustment
The rubber seal on the fuel
tank is important to the
function of the engine. The fuel tank is pressurized by the exhaust system
to provide reliable fuel flow. If the tank lid does not seal properly, an air
leak will be created that can cause your engine to run erratically and be
difficult to start. If necessary, the rubber O-ring tank seal can be adjusted for
improved sealing by tightening the screw on the underside of the tank lid.
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 minors 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.
Fuel is flammable. Only use outdoors. Keep fuel away from all
sources of ignition (flame, sparks, heat, etc.).
THE TRX 3.3 RACING ENGINE
