G-tech Results & the Race Ticket
Many people take the G-tech to the drag strip and compare
the G-tech’s results against the race ticket. However, due to
the effects of rollout, it is unlikely that the numbers will line
up perfectly.
Your staging technique at the track has a large effect on your
race results. A long rollout (shallow staging) provides more of
a “running start” for your vehicle before it crosses the starting
line. (When we say “crosses the starting line”, we mean “rolls
far enough to unblock the stage beam.”) This running start
can shave several tenths of a second from a vehicle’s E.T., and
add a small amount to the trap speed as well.
The following chart demonstrates the effect of rollout on the
1/4-mile E.T. and trap speed. In this chart, the driver drives
the EXACT SAME WAY, the only difference is how much
rollout the driver uses, i.e., how deeply the driver stages. (In
this example, for the sake of illustration, we are assuming the
vehicle pulls about 0.35g of acceleration continuously
throughout the run.)
Notice how significantly the E.T. is affected by rollout dis-
tance, whereas the effect on trap speed is minor.
This chart indicates that the E.T. for the exact same driver in
the exact same car can vary by approximately 0.5 second just
because of rollout!
In other words, significant time discrepancies can arise at the
track due entirely to rollout. The time it takes to roll those
first few inches has an enormous effect on the timed mile-
stones (e.g., 60 ft. mark, 1/8 mile mark, 1/4 mile mark).
Rollout
Distance
0 in. 4 in. 8 in. 12 in. 16 in.
Rollout
Time (s.)
0.000 0.226 0.319 0.391 0.452
Speed at
end of roll-
out (MPH)
0.00 2.01 2.85 3.49 4.02
1/4 mile
E.T. (s)
14.215 13.991 13.899 13.829 13.770
1/4 mile
trap speed
(MPH)
126.63 126.64 126.66 126.67 126.69
Rollout.fm Page 1 Friday, July 11, 2003 8:42 PM
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