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G Tech performance meter.. tool or toy?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Cavalry, Feb 18, 2001.

  1. Cavalry

    Cavalry 1/2 ton status

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    So whats the real deal with this thing? Is it worth the $120? How accurate is it? I'm a tuner at heart so accurate 0-60 times are a must.

    Luke
    84 K5
    [​IMG]
     
  2. Peeetah

    Peeetah Registered Member

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    My buddy has one

    But, he drives a supercharged 1998 540 BMW with 406 hp. He actually just used one for a month or so. It's kind of a one time use kind of deal. I don't think it is really applicable for a K5 Blazer
     
  3. Cavalry

    Cavalry 1/2 ton status

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    Re: My buddy has one

    It may not be applicable for a rig that just crawls rocks. But If I can squeeze 20 horse out of somewhere its worth it. I have rejetted carbs on a 454 I was dynoing and gained 65 hp. Its kinda hard to tell if you have made any gains on your work by just seat of your pants. Most carb guys just rely on a stopwatch. But thats kinda hard when your driving

    Luke
    84 K5
    [​IMG]
     
  4. Dragworm

    Dragworm Registered Member

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    Anything that is measuring 0-60 is very dependant on exact conditions to give you comparisons of performance. It takes a fair amount of horsepower gain to make a heavy vehicle like a blazer measurably quicker. You'd probably get just as much false info by changing something and running it on a cooler day. I've used one but mostly for the g-readings setting up a race car for autocross.

    So, which one of you is the brains of the operation?
    To tell you the truth it's not exactly a "brains" type operation.
     
  5. Shawn

    Shawn 1/2 ton status Premium Member Author

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    Believe it or not, that little thing actually works. I had one and I wish I would of kept it. Both the Grand Prix and Sy/Ty crowd uses these things to see how a mod improved the performance. It's been tested on a real 1/4 mile and it was pretty darn close to the actual time. You have to enter the weight of the vehicle so it takes a few things into consideration. It doesn't take the weather into consideration so the temperture should be the same if you're comparing a change to the vehicle. JC Whitney has them and I think you can get 10% off on one of their cats.

    Shawn
    87 K5
    few mods[​IMG]
    <A target="_blank" HREF=http://www.off-road.com/chevy>http://www.off-road.com/chevy</A>
     
  6. Eric78K5

    Eric78K5 1/2 ton status

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    The only real thing to remember is that at the track, your final trap speed is figured as an average of the last 66 feet, where the G-Tech will give you more of an actual speed, so your speeds with the G-Tech will be higher than anything you can do at the track. But the times are usually pretty close.

    Eric78K5
    K5-Because Size Matters!
     
  7. Blue85

    Blue85 Troll Premium Member

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    They're actually good within about 5% from what I understand. They use a little solid state accelerometer and quartz timer. Then the amount of acceleration is integrated over time to give you your speed and distance traveled. That's how it knows your 0-60 and quarter mile times. It determines HP by using an equation similar to this:

    HP = (0.00426 x MPH)^3 x WEIGHT.

    In this example, MPH is the speed at the end of the 1/4 and a fudge factor is used to account for drivetrain and tire losses. I have no idea what the actual equation used by G-Tech is, but this is why you have to enter your vehicle weight. Since a K-5 is such big box, the G-Tech will underestimate it's HP from 1/4 mile runs since it will not have the right fudge factor for wind drag. The drag from oversize tires will also decrease the measured HP.

    <font color=blue>"We have to take seriously the role in this problem of older men who prey on underage women..." Bill Clinton, 1996.</font color=blue>
     
  8. Cavalry

    Cavalry 1/2 ton status

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    This estimated HP is what kind of HP (flywheel, wheel, etc)???.

    Luke
    84 K5
    [​IMG]
     
  9. extremeblazer

    extremeblazer 1/2 ton status

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    I have owned one for about two years now and it works really well. The % of accuracy is listed on their web site for each of the functions. A few of the Hot Rod mags also tested them in a car used on a drag strip and the times the G tech received are really close to the drag strip times. The web site also tells how the hole thing works. I used it in all my muscle cars at the strip and the machine was about .002 faster then the strips clock. so thats really close. I constantly use it on all my cars and customers cars when tuning in an engine. The H.P. figures are based on whats coming out of the rear wheels. So even a change in gear ratio will change H.P. or a change in weight will change it. On my Blazer i keep track of 0-60 times because we need low rpm power. I found that hooking up my secoundarys on my 750 holley gained me about 22 hp over having them unhooked. But 0-60 times were still about the same so I gained more top end power, makes sence 1/4 times improved. I normally keep track of all my times and basic weather in a book so I can compare. The hardest part is finding a long/straight/flat area to open it up. Any thing different then flat and straight and the accuracy is off. Going up even a small hill will take more power then flat ground so time will be longer and H.p. is lower. Have fun.
     
  10. Blue85

    Blue85 Troll Premium Member

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    That's right, extreme, it would be really hard for the machine to compensate for slope. Even if it had sensitive tilt detectors in it, you would have to level it very carefully in your car and then the detectors themselves would likely be fooled by vibration and g-forces in the car.

    How is the G-Tech affected by cornering? Is the accelerometer unidirectional or strictly front to rear?

    <font color=blue>"We have to take seriously the role in this problem of older men who prey on underage women..." Bill Clinton, 1996.</font color=blue>
     
  11. Blue85

    Blue85 Troll Premium Member

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    In general, G-Tech readings are interpreted as follows:

    If it makes your car look fast, the readings are accurate.

    If it makes someone else's car look faster than yours, the reading is a rough approximation or in error.

    [​IMG] People really do treat them this way...

    <font color=blue>"We have to take seriously the role in this problem of older men who prey on underage women..." Bill Clinton, 1996.</font color=blue>
     

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