9
Tuning the Engine by Temperature
The following procedures require an optional infrared temperature
probe, an on-board temperature gauge, or the Traxxas telemetry
temperature sensor (part #6521). The engine can be used as an
effective tuning aid when you understand the relationship between
engine temperature and ambient temperature.
The engine operating temperature, when tuned for maximum
performance, will vary according to atmospheric conditions. The
atmospheric condition that has the most influence on engine
temperature is air temperature. Expect the engine temperature
to vary almost in direct proportion to atmospheric temperature.
Assuming you tuned the engine for the same maximum
performance each day, the engine will run about twenty degrees
hotter when it’s ninety degrees outside than it would in seventy-
degree weather. For this reason, we cannot give you a definitive
temperature range that indicates the best possible engine tuning.
The temperature gauge can aid you in tuning by giving you a
relative indication of how your adjustments are affecting the
engine and by preventing you from exceeding maximum engine
temperature. For example, as you lean the fuel mixture, the engine
performance will increase along with the temperature. If you
continue to lean the fuel mixture and the temperature increases but
the engine performance does not change, then you have exceeded
the maximum safe lean setting.
If tuning for maximum performance results in engine temperature
exceeding 300°F, try to increase airflow to the engine by cutting out
the rear of the body, windshield, and front valance. If the engine
temperature still cannot be kept in check, richen the high-speed
needle slightly.
Adjustments
Toe-in
Geometry and alignment specifications play an important role in
your truck’s handling, so take the time to set them correctly. Turn off
TSM (see page 5); then, set the steering trim on your transmitter to
neutral. Now, adjust your tie rods so that both wheels are pointing
straight ahead and are parallel to each other (0° toe-in). This will
ensure the same amount of steering in both directions. If you run out
of adjustment, then the steering servo will have to be re-centered
(see “Centering your Servos” on page 10).
For increased stability,
add 1°- 2° of toe-in to each front wheel. Use the turnbuckles to
adjust the alignment.
Camber
The camber angle of both the front and rear wheels can be adjusted with
the camber rods (upper turnbuckles). Use a square or right-angle triangle
to set the camber accurately. Adjust the front wheels to 0° of camber
(wheel perpendicular to the ground). In the rear, adjust the wheels to
1° to 2° of negative camber. These adjustments should be set with the
truck positioned at its normal ride height.
Shocks
The four shocks on Nitro Stampede have the
most influence on its handling. Whenever
you rebuild your shocks or make any
changes to the pistons, springs, or oil, always
do it carefully and in pairs (front or rear).
Piston selection depends on the range of
oil viscosities that you have available. For
example, using a two-hole piston with a
lightweight oil will, at one point, give you the
same damping as a three-hole piston with
heavier oil. We recommend using the two-
hole pistons with a range of oil viscosities
from 10W to 50W (available from your hobby
shop). The thinner viscosity oils (30W or less)
flow more smoothly and are more consistent,
while thicker oils provide more damping.
Use
only 100% pure silicone shock oil to prolong seal life.
The ride height for Nitro Stampede can be adjusted by adding or
removing the clip-on spring pre-load spacers. Instead of adding
spacers to increase stiffness, use stiffer springs. Adjust the ride height
so that the suspension arms are slightly above being parallel to the
ground. Observe how the Nitro Stampede handles in turns. If it is
picking up the inside rear wheel in hard turns, then stiffen the front
suspension. If it is picking up the inside front wheel in hard turns,
then stiffen the rear suspension. Proper set-up will add stability and
help prevent roll-overs.
Gear Ratios
A unique Nitro Stampede feature is the ability to change the gear
ratios. The final drive ratio of the gearbox is 2.81 to 1. Use the
following formula to calculate the overall ratio:
Nitro Stampede comes with a 70-tooth spur gear and a 20-tooth
pinion (clutch bell) gear. This combination will provide the best
overall acceleration and top speed. If you want more acceleration and
less top speed, then use a smaller clutch bell gear (fewer teeth). For
more top speed, use a larger clutch bell gear.
PRE-LOAD
SPACERS
Pinion
22
22
22
20
20
18
18
16
16
Spur Gear
66
70
72
70
72
70
72
70
72
Final Drive
8.43:1
8.94:1
9.19:1
9.83:1
10.11:1
10.92:1
11.24:1
12.27:1
12.64:1
ACCELERATION
TOP SPEED
Number of
Spur
Gear Teeth
Number of
Clutch
Bell
Gear Teeth
x 2.81 =
Final Drive Ratio
Toe-in
Positive camber
Negative camber
