G-Tech Pro Competition and Viper

[ewave]

Well I just got the Xmas present I bought for myself:

A G-Tech Pro Competition meter.
http://www.gtechpro.com/index.html

If you don't know about these, they are used to do 1/4 mile, 0-60, 1/8 mile, 60 feet etc. measurements of you car's performance.

I spent an hour reading the manual before I got the unit, so I knew how to get started. I'd recommend at least 15 minutes on the manual before fooling with the unit.

Here are the results from two runs I just did, back to back with my 97 GTS:

First run
1/4 mile ET 12.059
Speed 125.32
60' 2.159s
1/8 mile 8.049s at 98.60 mph
60 mph 4.129
1000 feet 10.233

Second run
1/4 mile ET 12.003
Speed 125.70 mph
60' 2.061s
1/8 mile 7.988s at 98.22 mph
60 mph 4.192s
1000 feet 10.173s

You just attach it to your wind shield with a suction cup, hook up the 12 volts adapter to the cigarette lighter, and your off!

I've got say they really hit a home run with this product. I paid $250 for it and am extremely happy and impressed. They also have functions where you can play back time to speed, distance rpm or acceleration. The data can be dumped to a PC for further analysis. They don't yet have the download software on their website, but they promise to have it soon. I was hoping to use that so show you guys an example of what the thing does.

The unit also makes a pretty good guess at the RPM of the engine. It does this I think by looking at EMI noise on the 12 volt line. You calibrate the unit to your car, and this function also appears to work very well.

I am not associated (yet) in any way with these guys. I am just a very satisfied customer, and I wanted to share my experience with you other Viper guys.

Also, on these two runs, I had tons of wheel spin in first and second gear. That's why the bad 60 feet times, and no 11's runs. From the dyno numbers for my engine, does it seem reasonable that with some practice I can get into the upper 11's

 

[PBJ]

Paul,
It is a pretty accurate piece, your MPH will be about 3-5 MPH high on your G-Tech VS. a quarter mile pass at the dragstrip. It will give you your exact speed at 1320 feet VS. the average of the last 60 feet of the 1320. I have found it to be within 2-3 tenths of a actual pass at the dragstrip. It is nice to use while trying new things without going to the track.
Later,
Joe

 

[VIPER1996]

I got one too, my runs 2.438 60ft 8.608 at 90.81mph in 1/8 and 10.960 1000ft and 12.998 quarter at 103 mph. My HP was 319.0 at 5140 rpm and 344.1 TQ at 4781 rpm with vehicle weight at 3800. It was me and another pass. We both weigh about 200 pounds each. My first gear is worthless and I mean worthless, I get pretty good tire in second. I don't think mine is set up right. It also said my 0 to 60 was 4.7 seconds. There is NO way I went 0 to 60 that fast. I have to let the clutch out slow and feather the gas lightly just to keep the tires from spinning. I can't even put the gas to the floor at all in first gear. I just use it to get the car moving and then shift to second. I was also at redline in third when it said I was at the end of the quarter, I didn't look at the speedo on the car to see how fast I was going, but redline in third is faster than 103 mph isn't it?? I can't go check because there is snow on the ground. I had the old GTech and liked it a lot!! This new one is really nice and light years ahead of the old one, it's just to bad I'm not. I plan on calling GTech for some help setting mine up. I read the manual and did everything it said, but I got some really wierd numbers on both my cars. Check it out!!! for the money it is worth it!! I just need to get mine set up right

 

[TriJim]

Let me jump on the "I like new G-Tech Competition Pro" bandwagon. Also not affiliated with manufacturer or distributors -- I received mine in a group buy with the Prowler Owner's Association.

Not wanting to be too much of a geek, here's the comparison of timeslips and G-Tech for 3 runs last Saturday night at Temple Dragway (sorry the columns don't line up):

Timeslip:
Reaction 0.5673 0.964 0.6623
60 ft 2.205 2.2254 2.2043
330 ft 6.2801 6.3054 6.2719
1/8 ET 9.738 9.7677 9.7259
1/8 MPH 71.83 71.65 71.95
1/4 ET 15.2559 15.2919 15.2306
1/4 MPH 88.73 88.6 88.89

G-Tech
60 ft 2.218 2.217 2.216
330 ft 6.219 6.243 6.219
1/8 ET 9.605 9.652 9.599
1/8 MPH 73.44 72.91 73.54
1/4 ET 15.063 15.152 15.048
1/4 MPH 89.88 89.1 90.13

If you didn't notice, this is the Prowler since the Viper is waiting to turn 2000 miles. Time and distance in the G-tech are determined by the clock chip and accelerometers (not user settings), so I'd think this level of accuracy should be consistent among different cars. I was also impressed with the accuracy of the unit in showing engine RPM and shift points. Viper is up next, but thought you might not mind a picture of the Prowlers:

You must be registered for see images attach

ewave -- I think G-tech monitors the voltage output to calculate rpm. It must assume that alternator turn rate and volts out are directly related to engine rpm. Mine was surprisingly accurate after calibration at default 3000 and 5000 rpm.

 

[George Murray]

I haven't used my G Tech in three years. I put it on a 95 Taurus SHO 5 speed (bone stock, 18K miles), and with 1/2 tank of fuel and two adult males (I'm 185, my fat friend is 205), I got 14.84 @ 99 MPH. Second run 14.89 @ 98 MPH. That just seemed way too quick for that car. Now, we also ran a VERICOM in the car at the same time (dual lighter adapter), and it read within .05 and 2 MPH each run. Maybe both devices were AFU. Or maybe the SHO was unusually quick. Dunno...

Same day, used it on Venom 600 and got best of 12.20 @ 122. Back country two lane road, crowned, first two gears utterly worthless. The "G" readout on the VERICOM showed incredible acceleration numbers in third gear, though.

 

[KenH]

TriJim's numbers look pretty good to me. Within .1 - .2 sec and 1/2 mile per hour or so of the drag strip and probably most important, they look consistent from run to run which is what you need when evaluating mods or technique. I have the old model and the new Competition unit, but I haven't had a chance to try the new one out yet. The old model was very sensitive to how you mounted it in the car to get accurate or repeatable results. The new one should not be sensitive to this.

I'd still like to figure out a decent way to mount this someplace semipermanent rather than sticking it to the windshield though. Maybe that pillar gauge pod could be modified to fit one of these?

--- Ken

 

[KenH]

Gary,
The new one has 3 accelerometers, so it should be completely immune to the old ones quirks about directionality. This one also has temperature compensation, better noise immunity, etc. The one thing I am curious about is how well it can really pick up the RPMs off the noise on the DC power. If this is accurate, the ability to store runs and chart things like HP against RPM could be pretty useful, not to mention the shift light if you permanently mounted it.

--- Ken

 

[ewave]

Update on RPM accuracy:

The reported RPM seems to be within 1 percent

Gtech reports 5109 rmp at 99.09 mph in third gear.

By math and vehical data:

5109 rpm = 99.9 mph per the following math:

99.9 mph = 5109 x 1/1.3 x 1/3.07 x (17" + ((335 x 0.35) x 2)/25.4)) x pi x 60 minutes/hour

divided by
(12 feet/inch x 5280 feet/mile)

So on my car at least, after the calibration I did, RPM seems to be within 1% of the real value 99.09 vs 99.90.

[edit: fixed rpm typo pointed out]

 

[Jack B]

The alternator is an ac device, when the rectifier (at output of alternator) converts to 12 vdc, there is a certain degree of ripple on the waveform. It is not just a flat 12 volt line. The ripple can easily be calculated and converted into rpm's when the device is configured.

 

[Tommy K]

ewave, didn't actually check you math, but you at least have a typo in your equation.

5109rpm = 99.09

then you have in you equation: 5190rpms...9&0 transposed
not sure if that makes a difference at all...just a fyi

 

[Skip White]

Paul I have the G-Tech meter as you have. I have not used it much yet. That manual is complicated to me, but I'm sure I will figure it out. What is interesting is that you're two tests are very consistent. That is what is most important. This seems to be an amazing device. I just need to find a 14 year old kid to help me figure how to use it. I have figured out the G-force mode and the rest lost me. I really just need to read it a few more times I guess. I like the idea of measuring the 60 foot times. You can do that anywhere. If this thing is within one or two percent of accuracy and consistent, then I'm going to love it.

Skip

 

[GaryA]

The nice thing about the Tazzo unit is that it has two accelerometers so you don't have to worry about leveling it out. I don't know if the new G-tech pro has this, but I know the original one didn't and finding level ground and leveling the unit out with the flimsy windshield mount was a pain (and explains some of the differences between track timing and G-tech timing).

 

[Baron]

I got a gtech pro for Christmas as well, and I've been using it every day for the last week. Everything seems to be pretty accurate except the HP measurement which was low, around 330 rwhp. Anybody else notice this?

It seems like the accuracy of the measurements really depend on specifying the most accurate vehicle weight possible. I'm really not sure what weight I should enter since I wonder if things like the weight of the gas in the tank should be added in?

 

[ronviper]

The G-Tech is not accurate but will give base line for bolt on's you make. It's a good starting point if no dyno is available, or track for all performance bolt on's you make.

 

[ewave]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Baron:
... Everything seems to be pretty accurate except the HP measurement which was low, around 330 rwhp. Anybody else notice this?

... I'm really not sure what weight I should enter since I wonder if things like the weight of the gas in the tank should be added in?

<HR></BLOCKQUOTE>

All weight is relevant. I also got low readings. The device has to guess as to the amount of drag from air resistance. Since this is different for every car, and it is non linear with speed, this has to be a major source of error. The faster the car is moving the more of an issue this becomes. The problem is you can't do HP measurement in first gear because of all the wheel spin, and I also have this problem in second gear. By the time you get to third gear, the speeds are so high that air resistance has a major effect.

 

[VIPER1996]

I had the same results with HP on both of my cars! I have never taken the Viper to the Dyno, but my 68 cuda with 340 showed 393 ATRW and 413 TQ. The G-tech no where near that!!! I do have some what of a tire spin problem with the Cuda!!!!

Not to get off topic, but what is MPH at redline in 3rd gear on gen 1

 

[jcaspar1]

I ran my original G tech at the drag strip. It showed me 414RWHP which correlates pretty well with my dyno results of 422 RWHP SAE. I had installed a VEC-1 after the dyno run but still measured pretty close. ET was very close, MPH higher than the averaged dragstrip mph.

 

[Baron]

Has anybody got the software for downloading the runs into a PC?

 

[phiebert]

I think the G-tech (I have the old one though) and the Mustang Dyno's give similar numbers. Both are considerably lower than a Dynojet gives. For example, it's been a while since I used it but I think it showed 344 HP on the G-tech and I'm quite sure a Dynojet would be higher. Anyone dyno on a Mustang dyno? They admit to being conservative on the numbers.