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GTECH PRO Vehicle Performance Meter

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PeterTR7V8
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GTECH PRO Vehicle Performance Meter

Postby PeterTR7V8 » 10 Feb 2009 04:00

Has anyone had any experience with one of these gizmos?

http://www.gtechpro.com

It is described as a pocket dyno & gives readings on HP, torque, 0-60, G force etc. The RR model has race telemetry readouts you can download onto a computer. All this it does just by being stuck to your windshield with no sensors etc. Sounds too good to be true but it cost the same price as a few hours on a real dyno.

I don't know if I can stop myself from buying one of these. [:p]

More info:

How does it work?
Acceleration:

At the heart of G-TECH/Pro is a precision 3-axis accelerometer, a sensor that measures acceleration also known as G-Force. G-Force is what's keeping you in your seat and if it wasn't for that seat you would be accelerating to the ground at 1 G (32 feet per second per second).

Acceleration is measured in Gs and is one of the key things the G-TECH/Pro COMPETITION is measuring. You can see this when you position the unit horizontally, it will show 0.00G's on the X acceleration bar. If you position it vertically it will show 1.00G's.

Speed:

The G-Tech measures your speed and distance travelled by integrating forward (the forward direction is chosen automatically) acceleration over time. Basically, if you know how fast you are accelerating for a certain time period you'll know how much your speed changed after that time period. So if you start off from zero speed then you'll know what your speed is after every time period. These time periods are very small (a few thousandths of a second) and that's how G-Tech maintains its accuracy. However, if you don't start from zero speed your measurement won't be correct because you won't have a good reference point. Consequently, it's very important to start all of your measurements from an absolute standstill.

Distance:

Distance is measured in the same fashion, if you know how fast you are going for a certain time period you will know what is the distance travelled during that time period.

Horsepower:

The G-Tech measures horsepower though the formula: speed times acceleration times the weight of the vehicle. The more accurate the vehicle weight you enter, the better your measurement. The G-Tech measures delivered horsepower, sometimes also called Rear Wheel Horsepower. This horsepower includes the loss of power through the drivetrain which is usually 10-15\%. Rear Wheel Horsepower is what most people are interested in because that is what they experience when driving. The use of Flywheel Horsepower measurement is often used in advertising, but not very realistic when it comes to accelerating your vehicle.

The horsepower that G-Tech measures also includes vehicle aerodynamic drag. This means that if you tape over your headlights and grill, remove rear view mirrors and windshield wipers to reduce your drag, you will measure a Horsepower increase even though you didn't make any changes to the engine. After adding an aftermarket spoiler you will likely find a decrease in measured horsepower, since you increased the drag losses on your vehicle.

RPM:

Engine RPMs are sensed directly from the cigarette lighter voltage. No installation required at all with this true plug and play feature. The unique RPM feature is used for anything from realtime torque measurements to shiftlights.

What can it do?

The new G-TECH/Pro Performance Meter COMPETITION is a very sophisticated, cutting edge automotive tuning instrument. Weather you want simple RPM recording or complete Data-Acquisition. As an automotive enthusiast you will find recording acceleration runs and analyzing shift points, delivered horsepower and reaction times extremely valuable. Just imagine, having all that power of knowledge right there under your fingertips any time you want it, that's the new G-TECH/Pro COMPETITION. So, no more confusion after making modifications now simply get the results "before and after".

Measurements:

Reaction-Time
0-60ft time
0-330ft time BR> 0-60mph time
1/8mile E.T and speed
1000ft time
1/4 mile E.T. and speed
Horsepower
Torque
RPMs
Braking distance
Handling G's
Accelerating and Braking Gs
RPM vs Time Graph
HP & Torque vs RPM Graph
Speed vs Time Graph
Speed vs Distance
Gs vs Time Graph

How accurate is it?

There are several significant improvements over the original G-TECH/Pro Performance Meter that have been implemented in the new COMPETITION model. First of all, there are 3 accelerometers and they are fully temperature compensated. This in itself is a huge improvement in accuracy. Secondly there is a very sophisticated new calibration algorithm that allows much higher precision. Also the system now has 32 times higher resolution which speaks for itself. New Noise-Correction algorithms have improved overall accuracy as well. With all of these valuable features we are very proud to announce that the accuracy is now within 5/100 second. With the consistency at 5/1000 of a second! Absolute Horsepower and Torque measurements are within 3% and consistency within .5%!

Ease of use and installation:

The motto at Tesla Electronics has always been to bring you cutting edge technology without the headaches of complicated installation and wiring procedures. The G-TECH/Pro COMPETITION has all of its sensors built-in. This includes three precision temperature compensated acclerometers and intelligent RPM sensing circuitry. All you need to do is plug it into your 12V cigarette` lighter and attach the custom designed suction cup mount to your windshield.

The G-TECH/Pro COMPETITION is auto levelling. You can orient it any way you like with absolutely no degradation in performance. This is a new feature not available in our original G-TECH/Pro.

The G-TECH/Pro COMPETITION easily comes out of its bracket so you can study your race results up close. User friendly menus let you quickly review results, store logged runs and changes settings. Want to take the G-tech from one car to another? No problem. Specific vehicle data, such as weight and shiftlight settings can be stored and recalled for up to four different vehicles.



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Marko
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Postby Marko » 10 Feb 2009 11:54

as far as know...

not shure if it was about this new model or the old one.

its a toy. to calculate HP you need to input drivetrain losses (which you have to guess) , and the claimed accuracy and consistency is a laugh , its hard to get those results on a chassis dyno. results can be easily tampered with.

its cheaper to go to a chassis dyno to measure HP


ive seen similar software for the iphone or some cell phones with integrated accelerometers.

all of those data that it can measure you coud get (one time) in another form cheaper.

that device is probably the cheapest "logger" you can buy

but why not get a real logger, and equip the car with some sensors

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Postby grndsm » 10 Feb 2009 20:09

There are several applications for I-phone which use the internal accelerometer. From what I have heard, some of them are better than the Gtech and cost next to nothing... After you buy the I-phone [;)]

Leon
'94 Eagle Talon AWD Turbo 613whp <powered by Mitsu 4G63T
'80 TR7 Spyder GS-T <undergoing Mitsu 4G63T transplant :)
http://www.cardomain.com/ride/2472999

PeterTR7V8
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Postby PeterTR7V8 » 11 Feb 2009 04:28

Well I was hoping someone had actually used the thing & could speak from experience but I know its fun to be a cynic.

Leon, yes the ipod software looks like it will do some of the same things but from my research it is not as accurate & doesn't have an RPM input. The GTech meter has the RPM detector & has shift lights & an optimum rev shift light. It also has the PASS analysis software which looks pretty useful for lap by lap analysis. So added to the fact that I don't have any i-gizmos there is enough extra features in the GTech product to make it worth a couple of $hundy.

Marko, of course it's a toy. So is my TR7! The question is, will I like this toy? I've scoured the interweb for info about these things & opinion ranges from somewhat satisfied to very satisfied so I think I probably will like it. I hope so cos I've bought a 1/2 price one on ebay already. New engine funds have been delayed by 1 week accordingly.

The dyno measures only HP & Torque & our local dyno guy charges like un toro herido. I've been on a proper dyno twice recently costing a total of $NZ800+ (US400) so if this works it is going to be a cheaper way to quantify any changes I make to the engine & handling and because I don't have to install any sensors I can use it on any car.

I have my last dyno readout to judge its accuracy by so we will see. I'll be happy to let you all know.


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paul w
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Postby paul w » 11 Feb 2009 06:28

I was getting all excited about this gadget'til Leon and Marko gave us
the low down.I am a sucker for a gizmo and i await your critique on
the merits of this,Peter.

See ya. Paul


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Postby Underdog » 11 Feb 2009 13:35

I would be interested to hear your impressions. My take would be that even if not exactly accurate the consistency would be of greater importance. That way it could be usefull to access modifications and tuning. Also would be fun at track days to be able to compare lap times rather than just running around the track aimlessly.

Edit, just looked at it and doesn't appear to do lap times. Suppose you need a setup with a transponder for that.

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Postby Marko » 11 Feb 2009 14:54

i didnt know that dyno run's where that expensive in NZ

here it costs around 50euros for 2 dynoruns on a
http://www.maha.de/en/2193.asp and that is not a cheap machine.

there are some inertia dynos that are cheaper but less accurate.


why not get one of these http://www.innovatemotorsports.com/products/lma3.php its 250$ compared to 300$ (the price of Gtech)

and is a real logger, can be paired up with a wideband o2 that is very useful tool in tuning the engine after any modification.

since you're into hillclimb why not invest in some real equipment that you can use for long time.

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Postby grndsm » 11 Feb 2009 16:39

I know that it can be fun to be a cynic, but I did have experience with the early version of the G-Tech. Granted, it was in the late 90s and it was only a single axle accelerometer, but that thing was dreadful! Fortunately, I was able to return it to the store from which I bought it after suffering with it for 3 weeks.

The new G-Tech is supposed to be much better. But consider this, no one will take absolute numbers from this devise seriously, when it comes to comparing them to "real life" numbers (from the dyno or a 1/4 mile strip). They are however, OK for doing "before" and "after" modification comparison, where you are comparing % of improvement.

So given such limited use, I figure that you may just as well use the cheap I-phone application. [;)]

Marco, who said that inertial dono's are not as "accurate"? In US, DonoJet is the most popular dynamometer and it happens to be of inertia type. The repeatability of that dyno is simply amazing! I have tested on 3 different DynoJet with-in 2 weeks, back when I was competing in Dyno-King competitions. My figures between 3 different DynoJets were: 465hp, 459hp and 468hp!!!

There is something to be said about accelerating the drum of the same mass [:D]

The problem with inertial dynos is that they can not keep steady state load (lets say if you want to keep 5000rpms for 10 seconds and tune a that point). So that is when "load cell" dyno operators usually try to push their dynos (Mustang, Land & Sea and DynoDynamics) as the "real" tuning tool, rather than just a horse power machine.

Well, the funny part is that every time I tried to get one of those load cell dyno’s keep certain PRM range, they weren’t very happy with it and instead steered me toward sweeping test...

One more things to consider, it is much easier to manipulate load cell machine to fake the numbers.

Leon
'94 Eagle Talon AWD Turbo 613whp <powered by Mitsu 4G63T
'80 TR7 Spyder GS-T <undergoing Mitsu 4G63T transplant :)
http://www.cardomain.com/ride/2472999

PeterTR7V8
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Postby PeterTR7V8 » 11 Feb 2009 22:52

The GTech can store 2 hours worth of data & you can get lap by lap analysis by chopping up a session & overlaying graphs to compare RPM & G-Force. It requires an external timer or even better, in-car video to define the start of each lap but even without that you can make a raw comparison of your data by finding corresponding shift points etc. You could probably do this with any analysis software.

http://www.gtechprosupport.com/support/PASS.htm

The LMA-3 looks like a useful gizmo but it doesn't have a LCD display so I'd have to download the info to a laptop to get any info or run with the laptop in the car. The O2, manifold pressure, exhaust temp etc is beyond my realm of useful knowledge & those sensors require permanent mountings which make it impractical to use on other cars at club events.

There is video on YouTube comparing the GTech to the timing gear on a 1/4 strip & it is consistantly accurate to with 200ths/sec conducted by the inventor so perhaps not an unbiased test. But as you point out Leon, the important aspect is consistancy so it can show me whether the car is faster or slower. Often on track days I don't bother with tyre pressures much because I simply can't quantify the difference. This or something like this will give me the data to make comparisons easy.

The GTech dude testing 1/4 mile runs http://www.youtube.com/watch?v=mmfwg5eoAFs

There is also this video from an online car magazine comparing the iphone version to GTech which highly favours the iphone but it is not a proper test in my view. No calibration & no multiple runs!http://www.youtube.com/watch?v=0-DFbJQbeSY (read the comments)

Video guides here http://www.youtube.com/watch?v=hgRzh30IAjk
& here http://www.youtube.com/watch?v=-MSmO-jauis

The unit I've bought is the 2001 model upgraded to use the 2004 software. It was 1/2 price so I'm sure I could flog it off if I get bored with it for about what I've paid for it. The previous models were a lot less sophisticated & the newer models have a nicer display. I'm hoping it will be here before the club event at the Taupo track on Feb 21.

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by grndsm</i>

I know that it can be fun to be a cynic ...<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

It's even more fun to be wide-eyed & enthusiastic but the thump of reality can sometimes means it ends in tears. Time will tell.

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PeterTR7V8
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Postby PeterTR7V8 » 12 Feb 2009 10:34

I've just been trawling thru the technical info on the GTech website & I found the formula which you can use to calculate your theoretical top speed.

http://www.gtechprosupport.com/support/ ... s/aero.pdf

With 140HP at the wheels, a drag coefficient of 0.35 (same as quoted for Toyota MR2 wedge) & a roughly calculated frontal area of 21sqft I get a top speed of about 140mph.

141mph = cube root ((140hp x 150,000) / (0.35 x 21))

For a standard UK 2L motor (105hp quoted x 0.85 for transmission loss) it is 120mph, 115mph for Federal (92hp quoted x 0.85). This doesn't take into account tyres or transmission drag etc.

200HP = 160mph & to be able to reach 200mph you'd need about 400HP. Anyone close to that?

This web site does cube roots http://www.csgnetwork.com/cuberootcubecalc.html

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Postby Marko » 12 Feb 2009 15:09

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by PeterTR7V8</i>


With 140HP at the wheels, a drag coefficient of 0.35 (same as quoted for Toyota MR2 wedge) & a roughly calculated frontal area of 21sqft I get a top speed of about 140mph.

141mph = cube root ((140hp x 150,000) / (0.35 x 21))

For a standard UK 2L motor (105hp quoted x 0.85 for transmission loss) it is 120mph, 115mph for Federal (92hp quoted x 0.85). This doesn't take into account tyres or transmission drag etc.

200HP = 160mph & to be able to reach 200mph you'd need about 400HP. Anyone close to that?

This web site does cube roots http://www.csgnetwork.com/cuberootcubecalc.html

<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

aerodynamics is a pain in the ...
because every single part of the car reacts differently at different speeds.

im in the proces of converting the entire car in a CAD model to use in simulations. more info on my blog when i get some more work done. first thing done will be the engine.

Frontal surface are can be measured with a photograph with something in scale to base the measuring grid upon.

PeterTR7V8
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Postby PeterTR7V8 » 12 Feb 2009 18:45

There are several things the formula doesn't take into account of course & some of the variables are guesstimates but the result look credible.

For front surface area I just multiplied height by width minus an allowance for ride height etc.

Converting performance into mathematical formulas - this is how we ended up with computers in our cars! [:(!]

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Postby Marko » 12 Feb 2009 22:40

whats wrong with little electronics? [:D]

PeterTR7V8
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Postby PeterTR7V8 » 12 Feb 2009 23:40

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Marko</i>

whats wrong with little electronics? [:D]
<hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote">

Answer: People like me who charge a lot of money to fix them!!

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Postby PeterTR7V8 » 16 Feb 2009 21:23

My new toy arrived today. I've managed to calibrate the RPMs so now I need to weigh the car & find a flat peice of road. Might have some numbers by tomorrow. [:D]

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