My GTech Competition is pretty darn accurate. It really depends on how well you setup the GTech the first time, keep the power cable secured and if you enter an accurate weight of the truck.
Mine gave me a 13.1 1/4 time and it ran a 13.1 at the real track. The only variance was in the speed, it was a few mph high. The dyno numbers matched up very close too. It really is a great tool for seeing if a combo or other change made a good difference.
I'll Second BMDMAX, my friend has the pro i believe, we have used it in 3 different cars and it has been dead on w/ the exception of the MPH a little high. I don't know about the dyno numbers but it was used on my monte, a del sol, and harley truck, which all read dead on. The key is setting it up well.
The G-tech is very sensitive to grade. You need to have as close to perfect level path as possible. While it should result in reliable ¼ mile times, the G-tech is not capable of taking aerodynamics into account on the horsepower/torque tables. With the amount of air you are pushing with a HD truck, your HP/Torque is going to be lower on a G-tech than a chassis dyno. The pro is supposedly more accurate and has some outstanding capabilities with the computer graphing software. I own a Pro but have only played with the earlier models.
Regardless, it is still a very accurate tool to compare before/after modifications on the same vehicle. Just don’t get caught up in trying to compare your vehicle to others who have tested at the track or on the dyno.
I have had the chance of running a few engines on the dyno. I am interested in tuning the engine by change the fuel, ignition timing, camshaft timing, valve lash, camshafts, barrel valve ratios etc. I want to get the most out of the combination I can. I care about where it makes the hp and how long the rpm spread is above 80% of max, etc. Even then I don’t care about where the numbers are. I care about how it relates to the other engines we run. Maybe the bore/stroke combo is better because of valve shrouding, etc. I don’t care that I got 600hp and Joe blow is making 629 peak on a different.
Use the G-Tech as a tuning tool and you’ll be happy. Only care about the gains you are seeing with back to back runs with your stock baseline. Don’t worry about what others are running. If you buy one, make sure it is the newer Pro model.
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