G-Meter's Accuracy?
TECH Senior Member
Joined: Nov 2001
Posts: 7,036
Likes: 1
From: Lake Zurich, IL
as an additional tuning tool they can be useful... but that's about it... try telling anyone w/any knowledge at all "my car ran xx.xx @yy.yy according to my G-Meter" and you'll be laughed at heh
If you are talking about a G-Tech they have some interesting things. Good for a removeable progressive shift lift. Has cornering lights too.
The mount sucks completely though. You have to take care of it.
The mount sucks completely though. You have to take care of it.
For dialing in spark/torque they are a nice tool. The accuracy of the Gtech is based on 3 factors, 1) An accurate weight of the vehicle, 2) An accurate tach signal and, 3) The 3 accelerometers in the unit.
The first two are dependant upon the operator getting the most accurate data into the unit, the accelerometers are very accurate.
The Hp numbers are not rwhp but, total vehicle (which will be lower). The 1/4 times are pretty good. The pro model has the serial output so you can evalute the data on your laptop.
For the money, I think they are a good tool.
The first two are dependant upon the operator getting the most accurate data into the unit, the accelerometers are very accurate.
The Hp numbers are not rwhp but, total vehicle (which will be lower). The 1/4 times are pretty good. The pro model has the serial output so you can evalute the data on your laptop.
For the money, I think they are a good tool.
Depending on the model and what's in the guts you
might even be able to bring out the accelerometer
output signal and log it real-time with your other
sensors (provided you have that kind of cable).
Then you can tie acceleration in-the-moment to
delivered advance, AFR, etc. and this lets you select
point-tune values based on results, from a batch of
acquired data.
I have an original G-Tech and its core is an Analog
Devices ADXL105 accelerometer.
http://www.analog.com/UploadedFiles/...ts/ADXL105.pdf
Tapping the voltage output is easy enough, single wire
to the MPVI cable, read your +1G and -1G voltages to
figure a custom PID and you're done (aside from little
bug-a-boos like ground offsets etc.).
If you want to do it slightly cheaper and don't already
have a crusty old G-Tech laying about, there are kits
you can get for about 20 bucks a pop, plus all the
incidental hardware like case, cables, regulator and so
on.
For tuning you really only care about repeatability,
not absolute accuracy. As long as you maintain its
setup (nulling, orientation) there should be very little
drift.
might even be able to bring out the accelerometer
output signal and log it real-time with your other
sensors (provided you have that kind of cable).
Then you can tie acceleration in-the-moment to
delivered advance, AFR, etc. and this lets you select
point-tune values based on results, from a batch of
acquired data.
I have an original G-Tech and its core is an Analog
Devices ADXL105 accelerometer.
http://www.analog.com/UploadedFiles/...ts/ADXL105.pdf
Tapping the voltage output is easy enough, single wire
to the MPVI cable, read your +1G and -1G voltages to
figure a custom PID and you're done (aside from little
bug-a-boos like ground offsets etc.).
If you want to do it slightly cheaper and don't already
have a crusty old G-Tech laying about, there are kits
you can get for about 20 bucks a pop, plus all the
incidental hardware like case, cables, regulator and so
on.
For tuning you really only care about repeatability,
not absolute accuracy. As long as you maintain its
setup (nulling, orientation) there should be very little
drift.
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After getting myself all excited about this I decided
to just go and do it.
Voltage output is 0.5V (-1G), 2.5V (0G), 4.5V (+1G).
The absolute accuracy is about 2-3% (I see 0.98G
on the digital display pointing down, 1.02G pointing up).
I replaced the 12V cig lighter cable with a 9V battery
clip, to eliminate ground loop issues. $0.99, pack of 3
(junk box = free). I reused the cig cable minus the plug
for output, leaving the white wire to the ground (-)
and connecting the red wire via a 1K resistor to Pin 12
of the accelerometer IC. The resistor is just for "oops!"
protection.
So bickety-bam, 10 minutes on the bench, handful of
free or Radio Shack parts and there's your G-Tech as
a digital readout plus loggable 0-5V voltage output.
to just go and do it.
Voltage output is 0.5V (-1G), 2.5V (0G), 4.5V (+1G).
The absolute accuracy is about 2-3% (I see 0.98G
on the digital display pointing down, 1.02G pointing up).
I replaced the 12V cig lighter cable with a 9V battery
clip, to eliminate ground loop issues. $0.99, pack of 3
(junk box = free). I reused the cig cable minus the plug
for output, leaving the white wire to the ground (-)
and connecting the red wire via a 1K resistor to Pin 12
of the accelerometer IC. The resistor is just for "oops!"
protection.
So bickety-bam, 10 minutes on the bench, handful of
free or Radio Shack parts and there's your G-Tech as
a digital readout plus loggable 0-5V voltage output.
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Verdad Gallardo Here are pics of it. Even simpler if you want to run it off the cig
as usual, just bring out a wire and hope the ground gremlins are
sleeping, but I battery-ized it to be sure.
g = (V-2.5)/2
as usual, just bring out a wire and hope the ground gremlins are
sleeping, but I battery-ized it to be sure.
g = (V-2.5)/2
Launching!
Joined: Sep 2006
Posts: 226
Likes: 0
From: Kentucky
The newer G-techs are pretty accurate, so long as they are calibrated right. As was previously posted, you need an accurate vehicle weight. They make a great tuning tool, or to compare pre and post mods.
