Anyone who has ever modified
a vehicle to increase performance has an immediate
question the moment the job is done: Is it better?
Post-modification performance, judged solely by
eat-of-the-pants feel, unfortunately tends to
be heavily influenced by optimism. If you've just
bolted on several hundred dollars' worth of exhaust
system, for instance, the last thing you want
to hear is that the vehicle is slower than before.
But in some cases it will be.
Case in point. After years of owning a bone-stock
1990 Honda CRX Si, a few years ago we finally
relented and installed an equal-length header
and cat-back exhaust with larger-diameter pipe
and low-restriction muffler. We also fabricated
a cold-air intake system, picking up high-pressure
air from the front bumper area.
And the car seemed no faster than before. Acceleration
was indistinguishable from stock and top speed
remained a radar-verified 124 mph. Worse, gas
mile dropped nearly 25 percent.
Okay, we thought, airflow has been improved to
the point where as a result, either volumetric
efficiency has decreased or the air/fuel ratio
is out of whack and it's running lean, maybe both.
After living with the condition for months on
this rarely driven vehicle, occasionally doing
some research on fuel injector flow rates with
the thought of installing bigger injectors, we
finally installed an air/fuel ratio meter. Surprise:
it was running rich.
After installing an exhaust resonator upstream
of the catalytic converter, enough back pressure
was restored to bring air/fuel mixture back into
alignment. Presto: mileage shot up 30 percent
and acceleration improved.
During this whole process we'd itched to take
the car to a drag strip to record before-and-after
acceleration times, a sure indication of power
output and an invaluable tuning aid. But it was
simply too inconvenient and we contented ourselves
with the trial-and-error approach. Too bad the
Escort Passport G Timer hadn't yet been introduced;
it'd have saved us endless hours of work.
This clever device, measuring barely 5.5 inches
wide, 1.65 inches tall and an inch deep, is a
two-axis accelerometer, a performance computer
that can actually deliver quite a bit more data
than any dragstrip. As the name suggests, it measures
G forces and does so in all four quadrants: acceleration,
braking and left/right. Like a 'strip, it'll record
acceleration including elapsed time to 60 feet
and rollout (primarily a measure of driver reaction
time and staging technique, both crucial to winning
drag races); time to 330 feet, 1/8 mile, 1,000
feet and quarter-mile, plus trap speed. It also
displays braking distance and rate of deceleration.
If you're more concerned with handling and cornering
performance, the G Timer measures lateral grip
up to 2 Gs, about double what even a stock Corvette
can deliver in either lateral grip or braking
Two versions are offered. The base model GT1
($149.95) has a 32-character, backlit LCD display
and stores the last run in memory; the GT2 ($249.95)
has a high-visibility blue vacuum-fluorescent
display, stores 99 runs and comes with a power
cord/remote control to select modes and start
a run without reaching up to press a button on
the windshield-mounted unit itself.
With optional software CD and
connecting cable ($24.95), the GT2 will download
data to a laptop, Palm or PC. We chose the GT2
due to its enhanced capabilities and higher-visibility
display, the latter especially appreciated for
nighttime operation. (We've found that doing,
say, 25 consecutive quarter-mile runs, even on
empty roads, tends to attract attention, particularly
in faster vehicles. So we frequently test in the
dead of night, making the bright display invaluable.)
The display can be set to eight different modes.
For example, it will play back the ten best 0-60
or quarter-mile runs or all 99 stored in memory,
your choice. To record handling performance data
it can be set to display lateral Gs as a bar graph,
numerically or as a combination of both. Curious
how your driving style affects cornering grip?
Now you'll have the numbers, displayed to one
one-hundredth of a G.
Two options are available for either model: a
direct-wire cord ($29.95) for permanent installation
or for vehicles lacking a cigarette lighter power
source and a VPC bracket ($9.95), a mounting bale
Operation is dead simple. For quarter-mile runs,
stop the car, press the Hold/Start button until
the unit calibrates itself. That done, a message
appears, inviting you to start whenever you're
ready. An audio tone notes the conclusion of the
quarter mile run and ET and trap speed are displayed.
Once stopped, by pressing the up/down buttons
the complete data can be viewed at leisure: zero
to 100 in 10 mph increments plus time to distance:
60, 330, 1000 and 1320 feet.
The factory-default settings are so good that
although the driver can change parameters including
vehicle weight, rolling resistance, drivetrain
loss, aerodynamic drag CDA and others, even without
adjustment, acceleration runs are generally accurate
to plus or minus 0.1 second. Accurate horsepower
calculation does require some input for maximum
accuracy, particularly vehicle weight, and proved
to be equally accurate.
We test about 80 new vehicles each year and have
found the G Timer to be highly accurate. For instance,
in a Nissan 350Z coupe we covered the quarter
mile in 14.23 seconds at 98.4 mph, within 0.1
second and 1.5 mph of most major car magazines.
Rated at 280 hp, the G Timer calculated the 3.5-liter
V-6's power at 243 hp at the rear wheels, a very
Curious to see how much the
2004 Jaguar XJ8 sedan's performance benefits from
its new, lightweight aluminum construction, we
clicked off 0-60 in 6.87 seconds and the quarter
mile in 15.13 seconds at 92.6 mph. For a smallish
4.2-liter, 300 bhp engine, this suggests that
the Slim Fast approach to car construction and
a new six-speed automatic clearly have benefited
the plush Jag's acceleration numbers.
We've used other performance
computers but the Passport G Timer raises the
bar another notch in accuracy, utility and user-friendly
operation. Short of owning a dragstrip or race
track, for the enthusiast owner it's the best
investment you'll ever make.