G-Tech Pro Competition, User Manual

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G-TECH / Pro Competition User Guide, Release 3.1
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Some notes on horsepower runs
• There is significantly less wind drag in 2nd gear as
opposed to 3rd gear; that is the reason we chose 2nd
gear in this example.
• No matter which gear you do your runs in, be sure to
use the same gear for all runs you wish to compare.
Suppose you do a 2000-7000 RPM run in 2nd gear and
another run from 2000-7000 RPM in 4th gear. The run
in 4th gear was at a much greater speed, and hence the
aero drag was much greater. This will have the effect of
lowering the
net horsepower on the 4th gear run.
• Vehicles with extraordinary power, or poor traction,
may spin the wheels at full-throttle in 2nd (and even
later) gears. The G-tech horsepower measurement
relies on no wheelspin being present, just like a chassis
dyno. If your vehicle experiences wheelspin in 2nd gear,
please perform the run in 3rd (or 4th...) gear.
• Be sure to do multiple runs and average the results for
the most accurate and repeatable numbers. You can use
the G-tech’s PC Analysis Software to assist with this.
• Remember that with the G-tech, repeatability and tun-
ing is the goal here, not necessarily comparisons to mag-
azines or dynos.
• Vehicle weight is factored into the horsepower calcula-
tion. This number should be as accurate as possible.
Refer to “What does my vehicle weigh?” on page 160
for more information on vehicle weight.
• External environmental conditions such as wind, air tem-
perature, and humidity affect
net horsepower . The same
vehicle with the same driver will measure more net
horsepower at 32 degrees Fahrenheit than it will at 100
degrees Fahrenheit. Cold air is more dense, and hence
contains more combustible oxygen. That’s why your
vehicle feels so much stronger when it’s cool outside!
• Cars with Continuously Variable Transmissions (CVT)
might be a problem, as the G-tech relies on gear shifts
and broad RPM ranges when determining peak horse-
power and torque. For these situations, you can use the
G-tech’s Horsepower vs. Time graph to find the peak
horsepower value by hand.
• Make sure that your RPMs are calibrated properly and
working throughout the entire RPM range before doing
a horsepower run. Otherwise your results will be
skewed.