Once all four tires and wheels...
Once all four tires and wheels are united, it's time for high-speed, computerized spin balancing. The John Bean VPI balancer pinpoints exactly where any imbalance is located and how much weight is required to eliminate the imbalance. In this view, you can see where the wheel center is bolted to the inner- and outer-wheel halves. Forty high-strength stainless-steel nuts and bolts are used to secure the three parts that make up each HRE modular wheel together as a unit.
The chassis dyno results-or lack thereof-really didn't surprise me. We made two baseline pulls, which were essentially identical to the final dyno runs at MagnaFlow earlier in 2003. The two pulls with the "performance tune" were almost identical to the baseline runs; there was not enough difference (no more than 1-2 hp and 1-2 lb-ft of torque variance at any rpm level, 1/2 to 2/3 of 1 percent) to be of any statistical significance. I really didn't expect much because stock late-model cars with computerized electronic fuel-injected engines are so finely tuned and so thoroughly optimized with sensors monitoring and reacting to changes in milliseconds, that there's not really a lot to be gained by fiddling with the factory settings. If the C5 was modified beyond the most basic of bolt-ons, i.e. cat-back exhaust and X-style crossover pipe and, still to come, a freer-breathing induction system, then the Predator's abilities to reconfigure the parameters could make a significant difference in the power output. If I wanted to change over to a lower temperature thermostat, I could use the Predator to kick on the engine's twin electric cooling fans at a lower-than-preset temperature. But with the car essentially stock, well, there doesn't appear to be a lot to be gained.
On the other hand, a lot was gained by retiring the C5. This formerly subtle, sedate, and understated Corvette now stands out from the crowd. It's purely a subjective judgment, but it now rides much smoother on the "Yokes" than on the OEM Goodyear run-flats. Its handling is much crisper, the grip feels significantly higher, and the steering feels more responsive. That's an interesting transformation-better ride and better handling.
Weights are affixed to the...
Weights are affixed to the backside of the wheel (where they're out of sight) with high-strength pressure-sensitive adhesives. An arm and roller on the balancer actually pushed the weight into place with enough pressure for it to hold to the wheel.
This new tire and wheel combo also provides improved grip for the 13-inch Wilwood Big Brake kit that we installed a couple months ago ("Late Braking News," Oct. '03). We snuck over to our nearby and highly illicit test facility (a local, very lightly used industrial street), plugged in our trusty old Tesla G-Tech Pro, and ran a quick series of 60-0 stopping distance tests. In totally stock form, the '00 coupe had repeatedly stopped from 60 in a quite credible 122 feet. With the 13-inch Wilwoods lurking within the stock 17- and 18-inch wheels, still shod on OEM run-flats, the coupe had given us a string of 60-0 stops in 111 to a best (on our last stop of a half dozen) of 109 feet. With the improved grip of the AVSs, we saw six straight stops (three going west followed by three headed east) from 60 mph in just 103 feet! No fade, no drama-just the prodigious stopping power of superb ultra-performance tires and serious, race-bred brakes.
The only downside to the new Yokohama AVS tires is that they set up quite a howl on some (but far from most) types of the grooved pavement we have on local SoCal freeways.
What looks gorgeous to one person may be ugly as sin to another. My subjective opinion of the HRE 549 wheels is that they are stunning! I think they look great. In the three or four weeks since the new tire and wheel package was installed, I've had several Corvettes-and a new Porsche cabriolet-pull alongside at stops and want to know who made the wheels and where could they get a set. I've never experienced that before.
At the start of this article I asked the question, "Is bigger better?" In this specific instance, my answer is an unequivocal and resounding, "Yes!"
Editor's Note (We'll be back next month with the installation and tests of Wilwood's 14-inch front brake kit. In addition to the normal street compound pads, we're going to install, bed-in, and test a set of Wilwood's PolyMatrix "E" pads-a slightly streetable compound that's engineered for serious track usage. I won't be surprised if we end up with some sub-100-foot stopping distances from 60 mph.)
 These are the old and new...  These are the old and new right-front tires and wheels. What a contrast-and a great example of plus sizing. The old and new combos are nearly identical in overall diameter, yet the original tire is 245 millimeters wide overall on a 17-inch diameter wheel, while the new tire is 30 mm wider (275 millimeters) on an 18-inch diameter wheel. |  These are the old and new...  These are the old and new right-front tires and wheels. What a contrast-and a great example of plus sizing. The old and new combos are nearly identical in overall diameter, yet the original tire is 245 millimeters wide overall on a 17-inch diameter wheel, while the new tire is 30 mm wider (275 millimeters) on an 18-inch diameter wheel. |  This is the Diablosport Predator...  This is the Diablosport Predator for Gen III V-8 powered vehicles which we ordered from Granatelli Motor Sports. On C5s, it plugs in to a data port under the dash near the steering column. It offers numerous tuning and adjusting parameters that should NOT be used by anyone other than an expert with access to a dyno with air/fuel ratio reading capabilities. It also has many features, like the ability to recalibrate a speedometer for gear ratio of tire-size changes, which makes it very worthwhile for any C5 owner who's contemplating minor modifications. |