Has Anyone Used A G-Tech Pro Meter?

[BO] I have G-Tech Performance Pro Meter and I would highly recommend to any car enthusiast out there, especially those who are always adding performance products to their cars. I bought it for $139.95. 1/4 mile times recorded on the G-Tech is pretty darn close to the track (difference will be how good your reaction time is). The 0-60 & 1/4 mile times have been very consistent.

Lowering the boost on my car did make a difference, meaning it works. The only function that I have doubts in its accuracy would be the horsepower measure. I get like 600hp readings which is impossible. Maybe Elite Motorsports can enlighten me and potential buyers on how to operate that fuction correctly. Otherwise, the unit is perfect for measuring 1/4 mile times (it even records your trap speed), 0-60, g-forces. For that price, it's hard to beat. The closest thing would be the Vericom Performance Meter which is priced approx. $1000. I would recommend it to anyone who enjoys testing out their car and how their performance goodies affect their car's performance. However, make sure you purchase the "Pro" model which is the new one. The old one just sucks and certain discount mail order companies sell them.

[DB] I've been using one for a month now. It's annoying because you have to mount it sideways for lateral g's, which makes it hard to read, but that being said, I feel it was worth it. My butt was not "g" calibrated at all, but now I have one semi-honest input. The device is somewhat toy-likecompared to the real racing stuff, but I'm not prejudiced for 10% of the cost of the real racing stuff.

[AWN] Alan Watkins offered to let me borrow HIS G-Tech Pro... I did (for way too long; sorry, Alan), and my friend and I experimented with it in a number of cars.

The plan was to first run it in my Porsche 914/6, since I have a dyno sheet for that engine against which we could correlate the data from the G-Tech Pro. Unfortunately, I haven't driven that car very much since I bought the NSX, and I've apparently forgotten how to shift it. My inconsistent driving, coupled with the accelerative shocks from the very-stiff suspension, meant that we were unable to get repeatable, believable results with the Porsche.

Next, we tried it on his BMW 2002 and had similar problems. He's a real smooth driver, but again, we were unable to get repeatable data from the thing... Too bad, since we had planned to do a before-and-after comparison of a new gearbox.

Tried it on the NSX and got mixed results. The acceleration data was OK (although we had to do that testing on the street since we no longer had access to the super-secret dragstrip that we'd used for the Porsche/BMW tests), but the braking data was very inconsistent; the G-Tech Pro had trouble deciding exactly when the car had come to a complete halt, and would sometimes keep timing even after we were stopped.

In desperation, we mounted the G-Tech Pro in my buddy's 1996 Taurus; we figured the soft suspension, automatic transmission, and only-average brakes would remove both driver inconsistency and high-amplitude accelerative loads from the equation.

We were right; the numbers we got were repeatable and (I think) realistic, although it took a fair amount of tweaking to get the G-Tech Pro absolutely level in that car (leveling the G-Tech is very important). I suspect that we might have gotten batter results with the other cars if we'd been similarly patient in leveling the G-Tech, but I don't know.

Overall, my impression of the thing is that it's a cute little gadget, but not useful or reliable enough that I'd go out and buy one.

[HH] Does it work? In a sense, yes. Consistency is good, accuracy sucks. We attached two of them side-by-side in my Ty and done a few test runs. Results were rather amusing - the difference between the times were ~0.3-0.5s 0-60mph, 0.2-0.7s at the quarter and trap speeds were as much as 8mph apart. Mine was consistently a bit more pessimistic than my friend's unit and more optimistic when compared against a Peiseler 'fifth wheel', which is accurate to 0.05%.

We've done tests with more than 1 G-Tech in a car, against Peiseler measuring wheel and Vericom and so far two G-Tech units have never showed the same readings. BUT, they're always been off by the same amount, which makes them great tools for figuring out how modifications affect your car. They won't give you accurate times but they will reveal if the modification you just made helped or not.

As I can't justify buying $10k worth of Peiseler measuring equipment I've considered getting a base model Vericom. The G-Tech is a nice toy and provides plenty of consistency for its price, but accuracy isn't (neccessarily - it must be calibrated first) its strong point.

 

FAQ on the G-Tech by a member of the Maxima mailing list:

What is the GTech/Pro?

The manufacturer's description:

The GTech/Pro performance meter is an accelerometer geared for automotive use. It's a small device that looks and mounts like a radar detector. However, instead of keeping you from meeting the local police, it might just introduce you to them. You'll want to make every stop sign a 0-60 run, every straightaway a 1/4 mile dragstrip, you'll want to fry your brakes in the name of a shorter 60-0 stop, and smoke your tires trying to get that extra .01g in the corners.

Well, you might not, but I did. I had to take it out of my car for a while so the tread on my tires would last a little longer.

The idea of the GTech/Pro is to monitor acceleration and use that data to generate the following data:

* 0-60 mph acceleration time
* 60-0 mph deceleration time
* 1/4 mile acceleration time and speed
* Estimated horsepower measurement. (Using vehicle weight that you supply)
* Instantaneous and continuous G-force measurement.

This data can be used to determine how a car is performing, in acceleration, braking, and cornering. This can be used to tune the car to achieve higher performance or to help a driver better understand how their car compares to others.

How does the GTech/Pro work?

The GTech/Pro uses a linear accelerometer to measure fore and aft acceleration. Side to side acceleration is measured by turning the unit 90 degrees. Using values for acceleration and basic physics, it can determine both velocity and distance traveled. This is how it is able to return 0-60 times and 1/4 times without being hooked into the vehicle speedometer. It's actually similar to the guidance systems of some missles which measure acceleration to figure out where they are, and adjust accordingly.

 

Does the GTech/Pro work?

In a word, yes. In all my testing with the GTech/Pro, I have found it to be very accurate. When I do a 0-60 on flat ground, the display stops exactly as the speedo needle crosses the 60mph mark. When I hit the brakes to do a 60-0, it stops just as the car does.

The numbers I have gotten have matched numbers I generated using other methods. (Thankfully, radar timing was not one of them) The GTech/Pro is very sensitive, and shows even slight changes of acceleration. If you want to know what your car is doing, the GTech/Pro is an inexpensive tool which will tell you in no uncertain terms. No more seat of the pants. No more guessing. No more making up fantasy numbers to impress your friends. (ie, no more B.S.) Just hard performance numbers.

It will return errant numbers if the conditions are not proper, however. In one 0-60 test, I was accelerating downhill, and the number returned was artificially high because of the downhill. To understand why, think about what it feels like when you are parked facing down a steep hill. You are pulled towards the front of the car by gravity, much like you would be if you were in the car while it was braking. Therefore, the acceleration figures the GTech reads are the actual acceleration minus the "apparent deceleration" of going downhill. So even though you are accelerating to 60mph, the GTech doesn't realize you're there yet because it hasn't been reading the same amount of acceleration.

The same would hold true if you were accelerating uphill, but this time it would read your actual acceleration plus the "apparent acceleration" of going uphill, and stop the timer earlier.

If you perform your tests on level ground, my tests have shown the unit to be very accurate.

Originally I planned on taking the GTech meter to a dragstrip where I could compare performance numbers from the GTech against the track's times, but I really never got a chance. Maybe when spring rolls around and I find some free time, I'll get out to a track and get some numbers for comparison. If/when I do, I'll post them here.

 

Shortcomings of the GTech/Pro performance meter.

1.Limited usability.

This is a very minor shortcoming, but it's one worth mentioning.

The GTech/Pro is not something which is going to help you out on a day-to-day basis. It is helpful when you install something new or want to test out a change in the tuning of your car, but during routine driving it's basically useless. It will tell you very accurately when you are accelerating and decelerating, and it is amusing to watch the GTech while the cruise control is on, but that's about the extent of its usefulness. It tells you nothing that would make you a better driver on public roads.

The GTech/Pro is a tool for measuring and increasing the performance of your vehicle. Once you understand that, you're set.

2.Single-axis measurement

This is not mentioned in the GTech/Pro homepage anywhere, and I think it is a little misleading.

The GTech/Pro only measures front to back acceleration. It does not measure side to side acceleration AND front to back acceleration, it's one or the other. This is because the accelerometer works along a single axis, from the front of the unit to the back. In order to make cornering readings, it is necessary for the GTech/Pro to be mounted sideways in the windshield. Reading the webpage, I, like I think most other people, read it as a two-axis unit. Although it doesn't say it's a two axis unit, it also doesn't say that it's a one axis unit either.

This is important for the prospective buyer to understand, I believe, and to be honest, in the place of the GTech/Pro makers, I wouldn't say either way as it might dissuade some folks not to buy it. Since I'm not selling the GTech/Pro, I'm reviewing it, I'm bringing it to your attention.

3.Mounting and the Power Cord

When I received my GTech/Pro, and opened it up, the first thing I noticed was the nice heavy plug and coiled power wire. I was impressed that the manufacturer hadn't cheaped out on a crappy lightweight Radio Shack plug and a skinny power cord.

In retrospect, however, I wish they had.

The plug is great. It's a nice, high quality plug. I've got no issue with the plug itself. The cord, however, is a heavy, coiled cord, very strong looking, about .155" in diameter. Unstretched, the cord is approximately 12-13" long, with about 4" of straight cord on each end. This means that unstretched, it's about 21" from the plug to the unit. Unless you have a high lighter plug, that's going to be close to too short. "Fine", you say, "it is a coiled cord, so it will stretch, right?" That's true, but since the cord is so heavy, it will pull noticably when you stretch it. I don't have any apparatus to give you a spring rate or anything like that, but it's a noticable pull. I've even tried fully extending it and holding it there, hoping that it would extend it a bit, but as soon as you relax it, it returns back to the unstretched length. A sign of a good cord? Yeah. But still a bad thing to be attached to a unit which must be level to be accurate. Another issue with the cord is its weight. Since it is so thick, it's quite heavy, and puts its weight on the back of the unit, trying to knock the unit out of level. Combine the weight of the cord with its strong spring-like qualities, it makes it hard to keep the GTech/Pro level, where it reads 0.00g.

I think, instead of the nice coiled power cord, they should have opted for a nice simple, lightweight straight cord. There isn't much need for routing the cable out of sight, as with a radar detector, but a lighter cord would put less strain on the mount, making it easier to keep the unit level. If you're thinking of replacing the cord, the cord is hardwired to the unit. It's not a plug-in cord which could be substituted easily.

This leads to the mount. The unit is very small, 2.8x2.2x.73 inches, and the mount is very simple. I'll try to get a picture of it to make it easier to understand. The problem with the mount is the way the angle adjusts. Two suction cups mount to the upper portion of the mount, which is bent into a cylindrical shape. A small cylinder fits inside of this, and a screw fits through the lower mount half and into the cylinder. Tightening the screw holds the current angle adjustment. It's very simple, but trying to fine tune the angle is next to impossible for a few reasons. First, the head of the screw is inaccessable when the unit is on the mount. The unit needs to be mounted in order for the level adjustment to be made, and once you have the unit level, it is necessary to lock the angle by tightening the screw. In order to tighten the screw, the unit needs to be removed from the mount. However, removing the unit can affect the angle of the mount. Also, the screw needs to be quite loose to adjust the angle, as it doesn't move freely when it is slightly tightened.

When I installed mine, I took a guess at the angle, tightened it up, and mounted it. It required only a little adjustment to get it to read 0.00 while stationary on a level surface. I was lucky. It seems that the mount could be hard to get adjusted perfectly without the luck factor. I also found that the disadvantage of the heavy spring-like cord could be used to my advantage by getting the weight of the cord to pull the unit back to level. It could be the manufacturer uses the heavy cord for just that reason. I don't know, I think a proper cord and decent mount would be a better solution.

Another issue with the GTech/Pro mount is the sideways mounting necessary for cornering readings. While the mount works suitably for fore and aft readings, it's downright crappy for side to side readings. You need to mount the unit level, but in order to do that, you need to pivot the mount. This can be even more difficult than the fore-aft adjustment, and it is also much more sensitive to factors such as the weight of the cord.

While the cord and the mount are disadvantages, it's important to note that they don't take away from the unit's performance. What they do is make it harder to set up the unit. The cord problem could be easily solved by the manufacturer, in my opinion. The mount issue might be a little more difficult because it is clear the manufacturer is trying to keep costs low to keep the unit price low. A stronger, easier to adjust mount could be more expensive, pushing up the price of the unit. I'd like to see a nicer mount, especially one which handles the sideways mounting cleaner, at least be an option.

 

Overall opinion of the GTech/Pro

In conclusion, the GTech/Pro is a great value for putting hard numbers on your car's performance. At $139, it's a fraction of the cost of comparable units. The accuracy is there, and I'm willing to put up with a few minor quirks to get something more reliable than a "seat-of-the-pants" dyno. Since I will be soon moving into a new house and will hopefully have more time and money to be adding more mods to my car, the GTech/Pro will be useful as I evaluate each.

 

Planned usage of the GTech/Pro

For power performance modifications, I don't plan on comparing 0-60 or 1/4 mile times, although I will get some readings. With a front-wheel drive car, especially one with a bit of power like the Integra, the launch is very difficult to get consistent results from. I've seen comparable runs over .5 seconds apart simply because of launch.

What I plan on doing is using the instantaneous/peak acceleration function at various engine/vehicle speeds to determine the peak available acceleration, which translates into available power. This takes out the effect of the launch, making the numbers more reliable. I plan on doing rolling starts from 1000rpm, 2000rpm, etc... from a steady-state (0.00g) to full throttle. The GTech meter can measure the peak acceleration, which can be recorded and averaged over several runs, giving a picture of performance improvements for the full engine speed range. This will also be easier to accomplish since it will be rolling tests and the locals won't always be wondering who the heck keeps peeling out in front of their house, leading them to call the local police.

 

Bonus uses of the GTech/Pro!

As an added benefit, if you have a 12V power supply, the GTech/Pro can be easily used for measuring angles. Place the GTech on the slope to be measured, and use a scientific calculator to get the inverse sine of the reading. Therefore, a reading of .71 would be approximately a 45 degree angle. The unit would need to be stationary for the reading to be
accurate.

 

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