# GTech Pro RR on the way!



## hsv (Jun 11, 2007)

Hi All:

I managed to score a GTech Pro RR on ebay for $175 (compared to $299 retail). It's in the mail, so I should be able to post some results soon!

I'm also looking at building an OBDII scanner with a friend. It looks pretty straightforward, so if I can get that working, and integrate the feeds with my GPS and the GTech's logging, I should have the goat pretty well instrumented!

Thanks to the guys on the GTech thread (I wasn't able to find it after a quick search). I've been wanting to get something like this for a while.

Cheers,

HSV.


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## NJG8GT (Nov 14, 2007)

hsv said:


> Hi All:
> 
> I managed to score a GTech Pro RR on ebay for $175 (compared to $299 retail). It's in the mail, so I should be able to post some results soon!
> 
> ...


congrats....let us know how it works when u figure it out.:cheers


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## hsv (Jun 11, 2007)

NJSierra said:


> congrats....let us know how it works when u figure it out.:cheers


Thanks! Will do. I'll post the results.

Cheers,

HSV.


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## hsv (Jun 11, 2007)

It finally got delivered today! Can't wait to get home and try it out.

I'll post results as soon as I have them.

Cheers,

HSV.


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## hsv (Jun 11, 2007)

*Report on Gtech Pro RR*

OK, so I've had my Gtech for about a week now, and it is pretty good. Here are my initial impressions.

When you first get it, you calibrate the accelerometer axes by holding it in various orientations (vertical, horizontal, tilt etc.). Then you calibrate RPMs by revving the engine to certain levels (4000 rpm, 3000 rpm). It asks for vehicle weight, and number of cylinders. Once you've done that, you are ready to go.

The person who sold it to me on ebay neglected to tell me that the cigarette adapter was broken (the wiring in the adapter plug was broken -- had to pull out the ohmmeter to figure this out). Fortunately, was able to get a new adapter from RadioShack for $10 (so $185 all up).

There are two modes of operation: drag mode and race mode. Drag mode measures 0-60', 1/8 mile, 1/4 mile, 0-60 mph, trap speed, and hp/tq curves (showing gear changes). It's very useful. In race mode, you see lateral and longitudinal acceleration (instantaneous) and you can log up to ~2 hours (at 10 Hz sampling). You can then feed that into the road racing software which plots these out for you in real time (along with engine RPM), and then maps your acceleration to a g-force circle (maps your lat/long acceleration into a circle) which allows you to see how close to the limit you are driving (the closer the better for racing).

Overall, the unit works well. There are a few glitches though. The biggest one is that the longitudinal acceleration is *very* sensitive to the position of the g-tech (angle). Generally you can calibrate it so that it is close to 0 at rest, but sometimes it's not that easy. The RPM feature is pretty neat, but can sometimes have some noise at low RPMs (or changing down) it can spike up to a few k RPMs before settling back to 800 or so (not too bad). The acceleration display is not so great (it shows instantaneous and the maximum over the last minute or so -- it might be a moving average). I've seen other units that show a graph v. time. This is a much nicer way to do it.

The unit also has shift lights, which are very useful. It's much easier to see the red flash out of the corner of your eye than having to look down at the tach.

I bought the unit mainly for the logging feature. I'm going to go SCCA solo-ing and wanted to be able to analyze my runs to see where I can improve. The unit is great for this. Drag mode is really good. It's nice to know how fast you are accelerating and also to see the engine "dyno" curves. I imagine that will come in useful if I ever decide to tune the engine myself (along with an OBDII scanner).

Physically, the unit was a lot smaller and lighter than I had expected (it didn't *feel* like $300). So that is about it.

One word of caution though... My first time out with it, I got pulled over (first time ever!). I was spending too much time looking at the unit rather than concentrating on what was around/behind me. I was on a straight four lane (2 each way) and was sprung doing 59 in a 40 zone. To make matters worse, my inspection sticker had expired. So there I am, sitting in the car, with my brand new Gtech-pro flashing away, with the officer telling me all of this. I knew I was gone, and resigned to getting a ticket. So the officer comes back and says to me: "I'm going to give you the break of the century..." and just gives me a warning. I think she couldn't believe she was doing it either... 

Cheers,

HSV.


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## Rukee (Feb 8, 2007)

I`ve had one I bought from NJSierra a while back for a great price. But I haven`t run it very much. I haven`t made any full out runs with it yet to check times and HP. On the original plug, check the end that goes into the lighter socket, the center contact end screws off and there`s a fuse in there, I blew mine too.


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## hsv (Jun 11, 2007)

Rukee said:


> I`ve had one I bought from NJSierra a while back for a great price. But I haven`t run it very much. I haven`t made any full out runs with it yet to check times and HP. On the original plug, check the end that goes into the lighter socket, the center contact end screws off and there`s a fuse in there, I blew mine too.


Thanks for the post. I did check the fuse when I got it and it was ok. The problem was with the plug itself. Somehow the wiring had become disconnected inside the plug (I'm guessing the previous owner might have pulled it out too hard).

The problem I was seeing with the g- offset is gone now. Apparently it recalibrates itself after it has been installed for a while. It works perfectly now. The HP/TQ v. RPM, HP v. Time, and other stats in the drag mode are nice. I'm very happy with this.


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## Rukee (Feb 8, 2007)

What are you getting for 1/4 mile times and HP ratings?


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