If you are reading this magazine, then you must be as crazy about high-horsepower cars as we are. If you are a true horsepower junkie like us, then the quest for far more power than your car came with is definitely one of your day-to-day concerns.
By Dave MacKinnon
 
 
With the thousands of different products available for our cars intended to improve performance, how do you know if your hard-earned money has been spent wisely? You can make a trip to a local drag strip, or try and schedule a lapping day at a local racetrack. A simpler, more cost-effective and considerably more interesting option is to purchase a Beltronics VectorPro GX2 vehicle performance computer. Quite the mouthful, isn't it?

The GX2 is an accelerometer-based performance measuring device. What does it measure? Lots! You have yourself a drag strip, chassis dynamometer and friction circle in one small little windshield-mounted box.

So how do you use it? Moisten the three suction cups on the back of the unit and stick it to the windshield. Now, plug the provided power cord into the cigarette lighter and watch the unit come to life. Using the G-meter button, select the drag strip mode and press start. There's one on the chassis of the unit, and one on the cigarette lighter plug. How convenient!

The unit will take a moment to calibrate itself then tell you that it's time to launch. You needn't press any buttons, or worry about any timing, just rev up the motor, dump the clutch, and target the horizon; the GX2 does the rest. When you have passed a 1/4 mile, the unit stops recording and instantly displays the run information. This information includes quarter-mile time and speed, 1,000-foot time, 1/8 mile time and speed, 300-foot time, 1/8-mile time and your 60-foot time. The unit also displays a mathematically calculated average and peak horsepower.

The horsepower calculation is based on a previously input vehicle weight. Acceleration over a specific amount of time for a given amount of weight is the basic formula.

The GX2 will also display cornering forces, given that it uses a pair of accelerometers. Unlike some previous performance measurement units, nothing needs to be relocated to measure cornering forces. The unit will display constant or peak hold forces in all directions if you are working on your driving technique.

The GX2 uses a two-axis accelerometer that is capable of measuring up to two Gs in either direction. The accelerometer provides a signal directly to an advanced RISC-based 8-bit processor. The processor includes and 8-channel, 10-bit A/D converter for sampling the output of the accelerometer.

During the design phase of the product a Racelogic VBOX satellite based system was used as the measurement reference. The VBOX is used by race teams, tire manufactures and other magazines for their testing. It would be nice to have one, but priced at well into the thousands, most people aren't likely to buy their very own.

The GX2 has many fine-tuning adjustments. You can input vehicle dive, squat and roll angles to compensate for suspension design and configuration. You can even set a roll-out distance for exact simulation of drag strip conditions. A drivetrain loss setting can allow you to calibrate the unit to display engine horsepower rather than road horsepower. The unit is sophisticated enough to even allow for a coefficient of drag and vehicle frontal area to make the horsepower calculation even more accurate.

Like I said, we like fast cars. I jumped at the chance to test the GX2 in a few different cars. My good friend Chad Whalen and I went out to see what sort of information we could gather with the GX2 in a straight line. We started with my WRX, and made a run to 60-mph, with my big honking 18-inch wheels. The GX2 reported an average of 5.5 seconds over three or four runs. Chad made the same run, only with prodigious amounts of wheelspin from his 2002 Pontiac Firehawk in 5.08 seconds. A calmer launch showed 5.48 seconds. The unit showed a horsepower rating of 172 hp for my car, and 277 for Chad's. The numbers seem to be about right, given the warm and humid weather of our test day. Don't forget, these numbers are road power, and include drivetrain losses and wind resistance, they are not engine horsepower

The GX2 will let you practice all sorts of high-performance driving techniques. The 60-foot and 0-60 mph times will let you practice your launches, and the lateral cornering force display will help with setting tire pressure. Having a high-performance car is one thing, but having a tool to help you get the most out of your car and training yourself is absolutely priceless. You will no longer have to guess what your car can do. No true automotive enthusiast should be without one.