Readers of the May 2006 issue of Super Chevy may have been left scratching their collective heads a bit by the time they reached the back cover. In the issue, there were two separate stories in which two manufacturer's suspension products were tested. In the test on the red Camaro (page 61) a host of parts from Heidt's Hot Rod Shop were bolted on, and the car was fitted out with super sticky Nitto NT01 competition tires. When it was later flung through the cones, it managed a best average speed of 48.5 mph. To put that in perspective, it ranks as one of the fastest cars we have ever tested-better than even a new Corvette. Trumpets sounded and praise was heaped upon this accomplishment.
But wait a second. Didn't another '69 Camaro get tested earlier in the magazine (page 43) and manage to go 58.39 mph though the cones while running on street tires? How could one story be singing the praises of the 48.5 mph run when another Camaro beat it by almost 10 mph? The answer is simple, and it's all in how the tests were done.
Out here on the West Coast,...
Out here on the West Coast, we rely on the use of tried and true timing lights to gather performance data. The Brower Timing Systems use optical sensors set up at the beginning and end of a measured distance to gather data. This system is simple and reliable, but the data it can generate is limited. Still, for the tests that most magazines perform, it's more than adequate. One advantage is that this system doesn't require a clear view of the sky to function correctly.
The first thing you need to know is that the most important part of any test is the consistency of the before and after testing. No matter what method you use for a test, it has to be the same each time so that the comparison is valid. For the blue Camaro in the Detroit Speed and Engineering test, great pains were taken to make sure all the variables were kept as consistent as possible. The before and after tests were done at the same location, on the same condition tires, and the same testing equipment was used in the same exact way. Because of this, the gains shown after adding the rear suspension parts are valid (and quite good). The car was tested using a VBOX data acquisition system. This little blue box uses very accurate GPS data and accelerometers to give the needed performance data. VBOX technology has been used by companies like General Motors for years, and is considered very reliable. In that story, the slalom performance was reported as the exit speed from the slalom. In stock form, the Camaro exited at 55.55 mph, and after the install or the DSE Quadra-Link the exit speed was 58.39 mph. A faster exit speed means that the car also had a faster average speed through the cones after the parts were installed.
In the story on the red Camaro, outfitted with the Heidt's suspension and R-compound Nitto tires, the testing was done with timing lights. A pair of lights is set up at the beginning of the 420-foot run, and another pair at the end. The time it took the car to go from point A to point B through a series of six turns was obtained and plugged into a formula to establish the average speed through the cones. This test was also done at the same location each time. In this case, the baseline of 42.1 mph went up to 44.1 mph with the Heidt's suspension upgrades, and then up to an impressive 48.5 mph with the sticky Nittos.
The GPS unit used to test...
The GPS unit used to test the blue Camaro was the VBOX Pro Lite. This small unit can be connected directly to a laptop for analysis in real time, and accurately gives acceleration figures, braking distances, and lap times. According to VBOX's Web site, its GPS units, when compared back-to-back with optical testing equipment, gives very accurate data. Maybe this is why its customer list contains almost every single auto and tire manufacturer on the planet. Racelogic's UK Web site has tons of data on the accuracy of this technology.
What you end up with are two tests using different points of data to show changes in performance after suspension upgrades. In both tests, the cars were ran through a measured 420-foot slalom course with cones every 70 feet. In one test, GPS equipment was used to report exit speed, and in the other test timing lights were used to report average speed. Both results, while valid, can't be compared to each other, but can be used to show that each car benefited quite a bit from the installed parts.
It's important when looking at any two separate tests to pay attention to how they are done, what exactly is being tested, and more importantly, how it's being measured. It's almost impossible to compare a car's skidpad numbers with hard radial tires to a different cars numbers running ultra-grip track tires. Just like there's no way to compare exit speed numbers to average speed numbers. It would be like comparing the average speed through a 600-foot set of cones to the numbers through our 420 feet of cones. The average speed through the 600-foot slalom would almost always be a higher number, even for a slower car. It's all physics, science, and the stuff we slept through in high school.
So there you have it-an exercise in how two cars can run the same type of tests yet yield results that, at first glance, seem so divergent from each other. The fact is that they should be viewed individually in regards to their reported gains.