Reaching the Apex

Whether at VIR or the ‘Ring, track testing played a critical role in honing the new ZR1’s performance edge

May 10, 2018
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One early morning in May 2016, the serenity of the undulating hills and vast expanses of picturesque woodland at GM’s Milford Proving Ground was fractured by the rhythmic thunder of an ultra-powerful Chevrolet V-8. Alex MacDonald, who was then Lead Development Engineer for Corvette and is now Vehicle Performance Manager for Chevrolet Performance Cars, strapped on a C7 ZR1 and eased it onto the Milford Road Course (MRC) for its initial shakedown. MRC is a 2.9-mile, 18-turn circuit that includes some of the most demanding features found on racetracks around the world.

As is always the case, the primary purpose of that initial test drive was to ensure that the car, an early integration vehicle hand-built at GM’s prototype shop in southeast Michigan, had no glaring problems. “The first test,” explains MacDonald, “is to make sure the fluids all stay in the car, and the wheels stay bolted on, and everything is basically functional and safe for the rest of the testing to begin. So you drive the car quite conservatively.”

Even when driven conservatively, however, the savage performance capability inherent in the still-nascent ZR1 made itself known. “The funny thing about that test,” recounts MacDonald, “is that I got onto the MRC’s front straight, taking a fairly conservative line because it was our very first lap with the car, and when I got to the start-finish line the speedometer said 168 mph. I radioed in and said, ‘I think we’ve got an issue with the speedometer.’ It seemed to be off by a pretty good margin, because that’s about 10 mph faster than we’d see with a Z06. After I finished the session, we pulled up the GPS data, and sure enough, lap one…was 168 mph. So we knew right at that moment that it was a special car.”

That the new ZR1 was so fast right out of the gate illustrates what can be accomplished when engineers with deep experience, innate talent and the most sophisticated computer-driven design and simulation tools available accept the challenge to create the latest in a storied line of “King of the Hill” Corvettes. But at the same time, the fact that MacDonald’s blistering first lap was only the beginning of a two-year-long journey that would transform ZR1 into an apex predator extraordinaire proves just how invaluable track tuning is.

“The role of track testing versus simulation is an interesting [question] right now, because a lot of things are moving to simulation environments,” explains MacDonald. “You have to consider the phase of the program and what tools are appropriate. So, early on in a program when we’re trying to decide how much power the car needs, [whether it’s] better to have more power or less weight, more aerodynamics or less drag—basically, where the compromises need to be made—we have really good simulation tools that help us. What we don’t have yet is really good simulation tools that let us do the fine tuning—or at this point, even the gross tuning. We can build a car that we know is capable of meeting our performance goals, but we can’t really get it any further than that without physically being at the track.

“Having the MRC on site for the past 10 years has brought a deeper understanding to the organization of how much information you can get quickly at a racetrack, and it’s changed the whole way we do business. It used to be that we thought we could do most of our testing on a regular proving ground and then go check the car on a track. It turns out [that] often, in a performance car, [it’s] much more efficient to go to the track early. We squeeze months of regular testing out of just a few hours on a racetrack, just based on the demands we put on the car. So, between those two things—the fact that simulation isn’t really up to the point where we can do much of the performance development, and the fact that we have ingrained the good-quality data you can get from a racetrack into our engineering lifestyle—track testing is a natural and required part of a program like Corvette.”

Hitting the Track

Also from Issue 122

  • LS-Powered C3 Restomod
  • Supercharged C7 Driver
  • C2 Buyer's Guide
  • 23K-Mile C1 Fuelie
  • LT1-Powered C2 Convertible
  • Racing: Hendrick Motorsports Corvette GTP
  • Interview: Tadge Juechter
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