SMC Networks T-Maxx 4910 - Manual (Page 24)

The TRX 2.5 Racing Engine
Flame-out - Occurs when the engine stops running at high
RPM. Usually the fault of an excessively lean fuel mixture or
glow plug failure.
Fuel - (10% 20%) The TRX 2.5 must have model engine fuel to
run. Traxxas Top Fuel is recommended. Fuel is sold in quarts
and gallons from hobby dealers. The 10 and 20% labeling
refers to the percentage amount of nitromethane contained in
the fuel (see “nitro percentage” definition).
Fuel mixture - The ratio of fuel to air as determined by the
needle settings of the carburetor.
Fuel tubing (fuel line) - The thick silicone tubing that carries
fuel from the fuel tank to the carburetor.
Glow plug - The glow plug is located in the cylinder head at the
top of the combustion chamber. It contains a platinum
element that glows red hot when voltage is applied. When the
engine is being started, the heat from the glow plug ignites
the fuel mixture and starts the combustion process.
Glow plug driver - This tool clips onto the glow plug and
supplies the required voltage to light the glow plug element. It
is also called an igniter. EZ-Start equipped engines do not
require this separate tool.
Header - The aluminum tube that connects the exhaust system
to the engine exhaust port. The length and diameter of the
header must be carefully selected to extract the most power
from the engine.
High-speed needle - Adjusts the carburetors fuel/air mixture at
high RPM.
Idle speed - The speed (RPMs) the engine runs at when the
transmitter’s throttle trigger is at neutral.
Idle speed screw - Located on the carburetor body. This screw
adjusts the idle RPM of the engine.
Lean - A running condition where the engine is not getting
enough fuel (for the available air). Symptoms include engine
overheating, or the engine runs for a short time and then
stalls, particularly at high speed. This is a dangerous
condition that should be corrected immediately or it can
ruin your engine.
Leaning the mixture - Turning either the high speed and/or
low-speed needle(s) clockwise to decrease the amount of fuel
the engine receives.
Low-speed needle - Needle valve that controls the low-speed
fuel mixture.
Needle valve - Valve consisting of a tapered needle that closes
against a corresponding seat to regulate fuel flow.
Nitro - Abbreviation for nitro methane, a component of model
engine fuel that improves fuel combustion and power output.
Nitro also refers to a class of RC powered by model engines
instead of electric.
Nitro content - The amount of nitro methane used in the fuel.
Usually measured as a percentage of the total fuel volume.
Traxxas engines are optimized to use 10-20% nitro. 30% nitro
may be used for racing.
Nitromethane - Nitro methane is a component in the fuel that
increases power from the combustion process up to a point.
Engines are generally optimized to use a range of nitro
content for the best power.
O-ring - Rubber “O”-shaped ring used as a sealing gasket.
Pipe - Abbreviation for the tuned exhaust pipe on a nitro
engine. See “Tuned Pipe” definition.
Piston - The piston is the internal engine part that is attached to
the upper end of the connecting rod and moves up and down
in the cylinder sleeve. The precise fit between the piston and
the sleeve creates a seal that allows engine to have the
required compression for combustion.
Port - Ports are openings in the sleeve that allow atomized fuel
to enter the combustion chamber and burned exhaust gasses
to exit. The shape and location of the ports are a large factor in
controlling the engine timing and power output.
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