G-TECH/Pro RR / SS / Competition FAQ

This FAQ covers the most common questions regarding the Gtech Pro RR, SS and 4.0 Competition products.
On this page, the Gtech products are often referred to as the "Gtech" for the sake of brevity.

Table of content

Common Problems

Q: My G indicator (on the main screen) doesn't seem to be working... when I am stopped, it still indicates acceleration. What is going on?

The RR (and Competition) differ slightly from the SS regarding the display of G force, but they function in a similar manner.  This response is general enough to apply to all Gtech products.

There are a couple of possibilities that explain why the Gtech would detect a non-zero G force when you are not moving.

One scenario is when the Gtech is not oriented identically to how it was on the last acceleration run. The Gtech needs to “re learn” its orientation before it can measure lateral and forward Gs. If you just mounted your Gtech, or moved/adjusted it since the last time you performed a run, you will need to do another acceleration run (at least enough to start the race clock) before the G bars are leveled.

Another possible cause: if the road has even the slightest slope to it, a small amount of Earth's gravity will be picked up by the Gtech's sensitive accelerometers and cause the bars to not “zero out.”

One last thing, if you believe you have not moved the Gtech since your last run, and you are on perfectly flat ground, it is possible it is a mounting problem. You should verify that the tensioning nuts are adjusted properly so that the Gtech is rigid and does not move. You should also check your mounting system and verify that nothing is cracked or damaged, including the rubber ball on the mounting clip, and narrow top portion of the conical “A frame” piece.

Q: On my Gtech I see the word “Diagnostic”, some numbers, and then the unit freezes. What can I do?

An internal error has been detected. Please contact us by phone in order to troubleshoot this.

Q: I am getting inconsistent results on my 1/4 mile runs. Why is this?

There are many factors that can affect your results. Read about them here.

Q: I am getting a message "The race has been discarded because the Gtech moved during staging" - what is this?

The Gtech requires you to "stage" on a level surface before performing a run.  During staging, the Gtech is checking its calibration and determining its orientation relative to the earth's gravitational field.  If the Gtech moves during or after this process, an accurate measurement cannot be made.  If the Gtech determines that this type of movement occurred, it automatically discards the run because the results will be inaccurate at best, and downright silly at worst.

Q: I am having trouble downloading stored runs from my Gtech into my PC - what can I try?

This is almost always an issue on the PC.  We have a Tech Note on this topic here.

Q: I am getting consistent results, but when I compare my results to a timeslip at the track, the numbers don't match. Why is this?

The largest culprit is rollout. In this case, nothing is wrong with the track or the Gtech, it's just that the Gtech and the track are starting the race clock at different times. The Gtech starts timing based on vehicle movement, and the track starts timing at an absolute position on the track.

Read this document to understand the effects of rollout and why matching the Gtech results to timeslip numbers is not too meaningful.

Another factor is vehicle pitch during acceleration and shifting.  Consult your product's manual about adjusting the Gtech's Pitch Correction Factor to "dial in" your results.

Q: My Gtech powers up (the blue backlight and red lights behind the buttons come one) but nothing appears on the screen, even after waiting a few minutes.

A sensor has failed inside of your Gtech. This is a hardware failure and must be repaired before the Gtech will function properly. Please contact us for service.

Q: I turn on my Gtech and a number of the LEDs blink in various patterns for 10 or more seconds, the the screen reads: DIAGS FAILED and shows ACCX ACCY ACCZ (or part thereof).

A sensor has failed inside of your Gtech. This is a hardware failure and must be repaired before the Gtech will function properly. Please contact us for service.

General Questions

Q: How many dragstrip runs can the Gtech store in its internal memory?

Up to 30.

Q: What are the dimensions of the Gtech?

Approximately 4 inches wide, 2 inches tall and 1.5 inches deep.

Q: I like the user interface of the SS - can I transform a Competition into an SS model?

Sorry, we do not currently offer a way to transform a Competition into an SS.

Q: I just bought a Competition recently and upgraded to the RR/4.0 firmware.  What is the difference between this product and the new RR model?

The Comp with RR/4.0 and the RR model have the same features.

Q: Can I use the Gtech on a motorcycle?  Snowmobile?  Boat?  Airplane?  Rollercoaster?

 The Gtech has not been subjected to exhaustive testing on these vehicles.  RPM pickup might be a problem, it is impossible to say if RPMs will definitely work for any given vehicle.  Without RPMs, you will not have the following functionality:

Also, in order for the Gtech's results to be accurate & meaningful, all timing must start from a complete standstill, and all motion must be on a flat and smooth surface.  Motorcycles generally exhibit a bit of pitch under hard acceleration, especially powerful/fast bikes.  This pitch effect will negatively impact the accuracy of your results (it cannot be quantified in a blanket statement, the effect varies on a case-by-case basis.)  Also be aware that motorcycles will also experience problems with lateral G measurements in turns, due to the severe banking angle motorcycles undergo in turns.

You should be able to use the Gtech on a snowmobile if the snowmobile travels along a straight flat surface like a frozen lake.  Do not use it on rolling terrain or sloped ground, your results will not be accurate.

Boats, planes and rollercoasters are not good candidates, due to the rolling and banking nature of their motion.

Q: Do I need a serial port on my computer to use the Gtech?

No.  You only need a serial port if you want to upload data from the Gtech to your PC.  If your computer does not have a serial port, you may use a USB-to-serial (DB9) adapter.  There are many such adapters, however we do not recommend or endorse any particular brand or product.

Q: How accurate is the Gtech?

The Gtech Pro Competition is extremely accurate and repeatable.  We routinely take 12 new Gtechs at random and subject them to testing in a controlled environment that eliminates variables such as pitch, mounting system problems, etc.  Typically,  all 12 Gtechs measure the same 1/4 mile time for a 1-g run, plus or minus five thousandths of a second.

For horsepower measurements, we have observed accuracy and repeatability in the range of 1-3 percent.

The accuracy and repeatability of your results can be influenced by many factors, such as vehicle pitch, road surface, environment, mounting system, driving style, etc.

Q: I am getting a message that says that "Two calibrations are needed at different temperatures for best results" - what is this?

The Gtech has temperature-compensated accelerometer sensors that are highly sensitive to temperature changes.  For best results, your accelerometers should be calibrated at 2 temperatures that are as far apart as possible.  If the Gtech determines the current temperature is far away from any temperature where you did a calibration, you will see this message.  If you see this message, go into Configuration Mode and perform an accelerometer calibration.

Q: When does the Gtech start timing?  When does it stop timing?

The Gtech starts timing when the car begins moving from a standstill and has completed the requested rollout distance.

The Gtech stops timing when any of the following conditions have been met:

For even more information, you may wish to download the 3.1 User Guide.

Q: Will the Gtech work on my vehicle?

Generally, the only potential issue is RPMs. Nothing else besides RPMs depends directly on your vehicle. Vehicles which travel in a flat, straight line will experience more accuracy and repeatability than those vehicles which crab, pitch, etc... on a run.

Q: Does the Gtech log lateral Gs?

Yes, in Road Racing Mode, the Gtech logs forward and lateral Gs as well as RPMs.

Q: Does the Gtech have a “peak hold” for forward and lateral Gs?

In Road Racing mode, the Gtech stores and remembers the peak Gs in all 4 directions (left and right turning, forward acceleration and braking), as well as peak RPMs.

Q: The Gtech stops timing shortly after I stop accelerating, is there any way to disable this?


Q: I use a throttle stop on my vehicle - will the Gtech still work for me?

The Gtech simply requires a smooth, strong surge of acceleration from a stop in order for it to "trigger" and start timing.  If your vehicle exhibits this behavior with the throttle stop mechanism, there will be no problem.  So far we have not encountered any problems with this.

Q: How do I determine my vehicle weight?

The very best way to do this is to get your vehicle weighed, in race trim, with you in it, at a truck stop weigh station, town dump, recycling center, etc. Actually weighing the vehicle takes the guesswork out of HP measurements.

If you do not have access to this, the next best thing is to obtain the curb weight of your vehicle, and add in the weight of any options, aftermarket parts, fuel, your body weight, etc...  Curb weight figures are available on the internet from a variety of sources, including vehicle manufacturers.  Unfortunately, we cannot provide curb weight for your specific vehicle, nor recommend any specific site for this information.

Q: I cannot get my 0-60 MPH time down to the figure that magazines publish. Why is this?

In firmware 3.0, the Gtech starts the 0-60 clock as soon as the vehicle starts moving. Many pieces of test equipment (such as some radar guns) don't start timing until a rollout distance of 12" has been completed.

In a 13-second 1/4 mile car, the first 12" can take almost four tenths of a second, and at the end of the 12", the vehicle is already moving at about 4 MPH! This means the clock doesn’t start until the vehicle has been moving for 0.4 seconds and has gone 12”.

Just as we urge people to not get too hung up on comparing results to the dragstrip timeslip, you shouldn't be too focused on trying to match published 0-60MPH figures.

Q: My mounting bracket occasionally falls off the windshield - what could be wrong?

We have a document that provides more detail on the mounting system.


Q: Is there a trade-in program so I can upgrade to a newer model?

Sorry, we do not have any kind of discount or trade-in program.

Q: I am an international customer, i.e. outside of the United States. What should I be aware of?

Please be aware of the following issues:

Q: Can I buy more than one Gtech at a time from your website?

Currently the website is set up to handle purchases of a single unit. If you would like to purchase multiple units at once, please contact us by phone.

Q: Is there a discount if I buy more than one Gtech at once?


Q: I lost my User Guide (product manual). Can I get another one?

You can download PDF versions of our user guides from our website. To purchase a hardcopy of the latest manual, please contact us by phone.  You can also use this form to order a hardcopy of the via the internet.

Q: How do I obtain accessories such as a spare serial cable, mounting system, etc.?

To purchase accessories, please contact us by phone or you can also use this webform to submit an order.

Q: Can I buy a specific component, such as a button, display or connector?

Sorry, parts used in the manufacture of the product are not stocked and sold as individual pieces. In other words, we do not sell individual displays, connectors, LEDs, switches, etc....

Q: What do I get when I buy the Gtech RR, i.e. what is included in the kit?

You get:

Q: Do you sell internationally, i.e. customers outside the United States?

Yes we do.

Q: How much will I pay for import duties/taxes?

This depends on your specific country and its regulations. Check with your government’s import laws and fee schedule to determine this.


Q: What is the maximum number of Gs the G-tech can measure?

+/- 10 Gs.

Q: Do I have to calibrate the accelerometers in my Gtech?

All Gtechs shipped after August 2003 have factory-calibrated accelerometers. Even though you can perform an accelerometer calibration yourself, it is unlikely that you will be able to improve upon the factory calibration. If your Gtech was delivered with factory calibrated accelerometers, we strongly recommend that you neither erase the accelerometer calibration, nor re-calibrate the accelerometers.

Q: Can the Gtech output accelerometer readings in real time so that I can log them with my PC?

No.  However, in Road Racer mode, you can log forward and lateral Gs at different logging rates, with different amounts of data smoothing, and then upload the data to a PC for analysis with PASS.


Q: Are there any firmware updates available for the RR?


Q: My firmware version is earlier than the latest version available for download on your website. Do I need to upgrade?

We strongly recommend that you upgrade your Gtech's firmware to the latest available firmware version.

For some issues, such as accuracy questions, we cannot even begin to narrow in on the problem until we know you are running the latest firmware.

Please note that upgrading your firmware will cause you to lose all stored configuration information and all stored runs. Thus you will probably want to make note of your configuration (vehicle weight, vehicle redline, vehicle shiftpoint, vehicle name, etc...) and also download your stored runs to a PC using the Gtech PASS software.

Q: I am having trouble upgrading the firmware in my unit, what should I do?

Make sure you downloaded the correct firmware upgrade program. Owners of Gtechs with firmware version 1.0 must follow a different procedure than owners with firmware 1.2 and later. If you have firmware version 1.0, or cannot resolve your issue, please contact us by phone.

Q: Will there be a firmware update for the RR or Competition? What will be in it?

We will not comment on future product development.


Q: Can I hard-wire my Gtech, i.e. I want to power my Gtech in a way other than through the cigarette lighter.

You can go to Radio Shack and buy a cigarette lighter outlet on a cord and attach that anywhere to your car's 12V electrical system. Some users have chosen to cut the Gtech cable at their own risk, and have attached it to their car's electrical systems directly. If you do this we strongly recommend that you put a 1 AMP fuse inline with your Gtech. Normally this fuse is inside the tip of the cigarette plug and if you cut that off, you will no longer have the fuse as protection.

Q: My car runs on a voltage higher than 12V. Can I still use a Gtech?

 The Gtech can operate at voltages from 9-15 VDC. The higher the input voltage, the warmer your Gtech might get. We don't  recommend exceeding 15VDC.


Q: Will the Gtech's RPM pickup definitely work on my vehicle?

We cannot guarantee with 100% definitiveness that the RPM pickup will work with your vehicle(s).  This is no different than an aftermarket tachometer.  Some vehicles present peculiar problems due to a variety of factors that are beyond our control.  We can say that the Gtech's RPM pickup works in the vast majority of cars we have tested on.  Unfortunately, the only way to know for sure is to try it.

Q: I have an MSD/Jacobs/etc. ignition on my car, will the RPMs work?

The RR/4.0 firmware has major enhancements in the RPM processing engine that work nicely with most aftermarket ignition vehicles we have tested.  However, it is impossible to say for sure if the Gtech's RPM pickup will work on your specific vehicle, because there are so many factors that affect the RPM pickup. We have even heard of inconsistent results within the same model year and make, perhaps due to aftermarket parts, alternator wear, part tolerances, electrical accessories, etc.. Some vehicles with aftermarket ignition systems work fine, others don’t, each one is a unique situation.

Q: What features rely on RPM pickup?

All of the acceleration-based measurements, such as 1/4 mile, 1/8 mile, 60 ft, 330 ft, 1000ft, as well as features like horsepower, cornering lights, braking distance measurements, 50-70MPH sprints, etc. will still work fine without RPMs.

Q: RPMs aren’t working on my vehicle, so can I disable the shiftlights so they don’t flicker randomly on and off?

Yes, you can disable the shiftlights, consult your User Guide for details.

Q: I moved my Gtech to another vehicle, but the Gtech's Tachometer doesn't match up with the vehicle. Why is this?

RPMs must be calibrated on a per-vehicle basis. This is why the Gtech supports up to 4 vehicles.

Q: Can I adjust the 2 RPM points at which I calibrate RPMs for my vehicle?

The two RPM calibration points are adjustable. Please bear in mind, the further apart they are, the better the calibration will be. Also, unless you have a diesel vehicle, we recommend that you do not go below 2000 RPMs on your low setpoint.

Horsepower & Torque Measurements

Q: The HP result from my Gtech is lower than the manufacturer's HP specification for my car's engine. Why is that?

The Gtech measures HP after all possible losses, including drivetrain loss, rolling resistance, and aerodynamic drag. All these factors rob your car of power. Manufacturer's specs are usually for an engine under ideal laboratory conditions, measured right at the crankshaft.

Q: The HP result from my Gtech is different from the results from my local rear wheel dyno - why?

The Gtech usually gives HP values which are lower than a traditional dyno. Lower figures are due to aerodynamic losses incurred during driving, and increased rolling resistance of the tires on a real road surface as opposed to a smooth dyno drum. In any case, the power measured by the Gtech is truly the amount of power left to propel your car forward, which is really what matters when tuning a winning vehicle.

Q: Can you give me an example with some numbers, i.e. suppose the manufacturer of my rear-wheel drive vehicle lists it as 320 HP... what will I see with the Gtech?

Here is an example.  These figures vary between vehicles and even within a family of vehicles... they are just provided for the sake of this example.

This is a very useful and meaningful value... for example,  you could have another vehicle (with similar weight and gearing)  whose engine is rated at 280 HP, and if that vehicle has fewer parasitic losses, it might "dyno" at 230 HP with the Gtech as well.  In this case, you'd know the vehicle would perform similarly, even though engine was rated lower than the 320 HP engine.  It all comes down to how much power is left to accelerate your vehicle.

Q: Does the horsepower / torque measurement work on a FWD vehicle? On an AWD vehicle?

Yes, the Gtech measures net horsepower, which is to say, the horsepower delivered through the driven wheels, no matter which wheels they are.

Q: Why does my dyno plot look "flatter" than the dyno plot I've seen from chassis dynos for my car?

This is primarily due to aerodynamic drag on your vehicle.  The amount of horsepower that is spent overcoming aerodynamic drag is proportional to the cube of the vehicle velocity.  In other words, you use 8 times as much horsepower just to overcome aerodynamic drag when your velocity doubles.  For example, if aerodynamic drag robs your vehicle of 3 HP at 25 MPH, it will be robbed of 24 HP at 50 MPH... the velocity doubles, but the aero drag loss goes up by a factor of 8!

So even though you are usually generating more horsepower at higher RPMs in a particular gear, you are also going faster, and the horsepower needed to overcome aerodynamic drag is much higher at the upper end of the RPM range.  This increasing "negative horsepower" due to aero drag is largely cancelling out the increased horsepower generated by the engine.

You can use this page to calculate the horsepower that is robbed due to aerodynamic drag.

Q: What is the difference between the HP measured by the Gtech, and the HP measured at a dyno, and the HP given in publications?

First of all, there are variances even between dynos. That is to say, if you take your car to 5 different dynos, you will probably get 5 different results. None of them are “wrong”, it’s just that they all measure in a slightly different way, under slightly different conditions. As any experienced tuner will tell you, when you are tuning/modifying your vehicle, you should always go back to the same dyno for comparison.

Most publications list the “crank horsepower”, which is the horsepower put out at the crankshaft, with no transmission, etc... connected to the crankshaft.

Most dynos measure “wheel horsepower”, which is the power delivered through the wheels (front, rear or all wheels); this power is what accelerates the vehicle forward. Consider all the mechanical components between the engine crankshaft and the wheels, as well as the friction (rolling resistance) between the rubber tires and the surface of the dyno roller, and it is no surprise that dynos measure a lower HP figure (after all, they are measuring power at a different place.) Some dynos have “tweaks” and adjustments that raise the measured wheel HP figure based on a number of factors, bringing the delivered number more in line with the manufacturer’s crank HP figure.

As for the Gtech, it will read even lower than a dyno, because of additional sources of power loss that affect a moving vehicle. One of the largest culprits is aerodynamic drag. Some other factors include road surface irregularities, environmental conditions such as wind and humidity, etc...

This document provides a lot of information on the Gtech and horsepower measurements.

You can use this page to calculate the horsepower that is robbed due to aerodynamic drag.

Q: I am getting inconsistent results when measuring horsepower and torque. Why is this?

There are many factors that can affect your horsepower/torque results. Read about them here.


SS Model

Q: What is the difference between the SS and RR products?
Q: Can I upgrade my SS into an RR product?

At this time the SS unit is simply an SS unit.  We do not comment on any future plans for upgrades or features.  You should not buy an SS unit with the expectation that it can be upgraded.

Q: Is the RR product more accurate (since it costs more)?


Q: Can I upload runs from the SS and use the PASS PC Software to analyze the data?


PASS PC Software

Q: What are the system requirements for PASS?

Windows 98 SE or higher (English version, we have reports of problems with some international versions of Windows), screen resolution of 1024x768 or greater, 32M of RAM, 20M of hard disk space.

Q: What features does PASS provide?

PASS allows you to view, analyze, export and share the data acquired by the Gtech during drag strip acceleration runs.  As of PASS 2.0, you can also analyze road racing / autocross / track sessions as well.

The best way to learn about PASS is to download it and try it for yourself.

Q: Can I try PASS on my computer?

Yes, the PASS software can be downloaded from our website for free, and it comes with some sample runs that you can use to “test drive” PASS.  The sample runs are located in a directory named "sample runs" in the PASS installation directory.  You can open a sample run by clicking on one of the 4 yellow folders and selecting a run in the "sample runs" directory.

Q: Can I export data from PASS so that I can use it in another program (like a spreadsheet)?

Yes, you can export the Main Run's data from the File pull-down menu. The data is in CSV (comma-separated values) format, with 0.01 second granularity.  Note: we have reports of difficulties from users in some European countries when this file is imported in Microsoft Excel.  This is due to the fact that some European versions of Excel use a comma where the American version uses a period.  If this is the case, you should use a text editor to replace all the commas in the .CSV file with tabs, so that it is tab-delimited instead of comma-delimited.

Q: The fonts in PASS seem to be messing up the screen - can I do something about this?

This is a Windows issue that is specific to your computer and over which we have no control. Also, different versions of Windows operating systems handle fonts differently. Having said that, make sure that in Windows, your Windows Font Size is set to "Normal" (Desktop->Properties->Appearance). Also make sure that your DPI is set to normal/96 DPI (Desktop->Properties->Settings->Advanced). With those settings, there are usually no display problems.

Q: When I compare my HP / TQ results in the Gtech vs. PASS, they don't match - why? Which one should I use / trust?

Sometimes PASS may not come up with the quite the same results as the GTech for HP/TQ measurements. The algorithm in PASS is virtually identical to that in the Gtech, but PASS does some extra "smoothing" on the acceleration data.  We anticipate that when Gtech firmware version 3.1 is released, and PASS version 1.2 is released, these numbers will be much closer to each other

Due to the high precision of the Gtech's accelerometers, things such as gearshifts, bumps in the road, etc. can add a little noise to the forward acceleration data.

Both the Gtech and PASS smooth out the forward acceleration data to provide a nice HP curve, but PASS uses a slightly different smoothing algorithm than the Gtech.

We have a Tech Note which explains more about using PASS -- download it from here.

As long as you compare PASS numbers against PASS numbers, or Gtech numbers against Gtech numbers, you will be fine.

Warranties / Refunds / Repairs / Replacements / Parts

Q: How does the 30-day no-risk satisfaction guaranteed offer work?

The 30-day Money Back Guarantee is explained here.

Q: What is the warranty for the Gtech Pro Competition?

One year. The Gtech warranty policy is explained here.

Q: How do I obtain an RMA so that I can send back my Gtech?

Our RMA policy is explained here.

 Q: I just bought a Gtech on Ebay and I have a problem with it -- is it under warranty?

The Gtech warranty policy is explained here.