I'm thinking of getting a g-tech to play around with. I just want something that is more accurate then my SOTP meter.

How accurate is the cheaper G-tech? Is the pro better and is it worth the extra money?

Is there anything else you can tell me about these?

Thanks

I like the software that comes with the pro model. Without that, you're stuck just reading the numbers on the unit. With the software, you can plot multiple runs on the same chart, and do so long after the fact on your computer.
The road racer part doesn't seem real useful unless you're running a road coarse multiple times.

How accurate is it? How does it read speed? GPS?

What about the real old cheap one. The $30 one on ebay?

I've not run it at a track to know for certain exactly how accurate it is, but I believe it is "reasonably" accurate. They say it should be within a couple hundreds of a second.
It does not use GPS... it uses an "accelerometer" which I think is basicly a Gyro which measures g-force in any direction, or more specificly the change of g-force.

My bet is that the accuracy on the old one is not what the new one is.

Too bad they don't use GPS. Then it would be accurate regardless of weight etc. Maybe I'll just buy a GPS that does 1/4 mile runs. Is there such a thing?

Hmmmmm.... I've owned several Garmins, none of them have had it.
I don't think a GPS would be accurate to less than a tenth of a second.

The G-Tech is very accurate, I have the Pro Comp with all the latest upgrades. It is very hard to do a comparison at the track, due to having so many things to remember at once. However; Out of three runs, I was able to get one comparison. The G-Tech read something like 7/100 slow while reading 3 mph fast. I seem to remember reading that the reason the G-Tech reads higher mph, is due to taking readings multipule times per second, while on a 1/8 or 1/4 mile track, you only get a few readings, then you get an estimated top speed.

A GPS could never give accurate track times, because it is only accurate to within a few yards. Military says within one yard, and the GPS they allow the public to use, is less accurate, (But I am not sure how much different!)
I have the Earthmate GPS, I have seen it showing me driving maybe 10-15 yards out in a wood line or field (On the other side of the road!) along side the highway. I have also seen it show me going straight for maybe 50-100 yards while taking an off ramp on the interstate. I did adjust and get back on track, but with them being off like this, there is no way you could ever get an accurate 1/4 mile time.

Too bad they don't use GPS. Then it would be accurate regardless of weight etc.

Weight does not fator into the accuracy of the G-Tech. Weight is used by the unit to calculate the Hp that it took to move the vehicle at the speeds it recorded.

Interesting. Thanks guys. I think I'll try to pick one up.

Max...fredw uses one.....might want to shoot him a pm

I considered getting one of those for our military vehicles. Since I am always tweeking w/ SCensored . However, we did use a GPS a couple of times to moniter vehicle speed because the speedometer was way past the mark... I think the civilian GPS's get 3m accuracy. They may have changed the tech though.

Most of the forced error that the government had in these units was removed during the Clinton administration. Prior to that you rarely saw under a 30' window of error. These days, mine typically "believes" it's accurate to less than 20', sometimes down to 9 or 10. That however will still not make them usefull for 1/4 mile times, but for checking your speedometer, or getting an average speed over time, they are very accurate.

Check out their website. http://www.gtechpro.com/
I have a G-TECH COMP, which is less than 2 years old. It's one of the first versions to come out with the big LCD screen and the DB9 so data can be loaded onto a laptop.
They have upgrades available from time to time also. I have updated mine to the latest firmware version online.
Here are some screenshots of a few runs I did awhile back. This is a sample of what the software can display. I had to resize it to fit so I hope you can read it.

As mentioned above, the only time you need to be concerned with entering the weight of your vehicle is if you want the G-TECH to estimate horsepower and torque. The 0 to 60 and 1/8th 1/4 mile times don't take weight into account.

The US Gov't turned off GPS SA (Selective Availability) back in 2000. What you see is what you get. The better GPS units are the ones that can track multiple satellites at the same time. Most new GPS units do that. Some of the older, early GPS units can't.

http://www.navcen.uscg.gov/gps/selective_availability.htm

I love my G-TECH Comp. It's a great analysis tool. While it may not be as accurate as the professional units that automotive magazine testers use, for the money you can't beat it. When you make some changes and you want to see if the results are credible, it is better than SOTP testing, especially if you can't go to a track.

The old G-Tech models are darn accurate too (the ones with only numeric display, no downloading to PC). Many people have ran them against track clocks. Times are fairly decently accurate, regularly under 0.1sec error.
Please do read user manual for MPH estimation. Track does not print out real top speed, they give average speed for the last ..umph.. 60ft(?). The G-Tech displays real mph, hence being higher than track timeslip mph figure.

Older models are biased towards error in cars with really soft rear suspension. Rear squatting changes chassis attitude, hence making the G-Tech to see erroneous g-force.
Those older models read fine with stiff suspension.

Tweaking older model to display -0.01G's before launch will make it more accurate in cars with squatting rear suspension.

PRetty acurate IMO but if you start claiming certian times in a 1/4 you better have a slip to back it up;) Fun tool too.

PRetty acurate IMO but if you start claiming certian times in a 1/4 you better have a slip to back it up;) Fun tool too.
Are you saying your 11 second 1/4 wasn't with the G-Tech?;) I'm disappointed!:lol:

Of course it was.....but I have the extra pro version that spits out time slips:D

Of course it was.....but I have the extra pro version that spits out time slips:D

I guess I got ripped off, as mine don't have the spitter;) :lol: