The other is half covered, but the exposed parts are unfinished with trim pieces missing. They're dead cars walking, since pre-production cars like this end their brutal lives in the jaws of a crusher. We're not here to look at them, of course.
The 755-horsepower smallblocks, force-fed with massive superchargers, quake to life. Resonating off the garages, they almost sound unrestricted, but without the teeth-gritting resonance you get when you straight-pipe a thing like this. I turn to Tadge Juechter, proud father of unreasonably quick Chevrolets, and ask if the cars here today are competition exhaust or something. He wrinkles his nose a bit. Nope, these are the stock pipes, street legal. "The ZR1 is a few decibels louder than the Z06," he says. To call this an understatement is generous. This is the loudest Corvette the company has ever made.
That's pretty much the ZR1 in microcosm: Everything's turned up a bit. Juechter and his comrades are gleeful, telling us about things that their new LT5 engine broke during the four years they developed it. Like dynomometers. Lots of them. The exhaust stacks would get so hot from the blast furnace that is this motor that they'd crack. Jordan Lee, the GM smallblock program manager, tells us this like the proud dad of an especially rowdy kid. So they tried water cooling jets. Then, showing the seriousness to which the GM engineers took this problem, they threw some money at it and built the stacks out of Inconel, a nickel-chromium superalloy. That did the trick. It took 10 times as long to validate the engine output, Lee says, because so much stuff broke. Engineers love these stories. They're good stories, though.
Outside, the ZR1s run some laps before we go out in the right seat, and Juechter and Lee continue educating us on what's changed compared to the Z06. We learned a lot of the broad strokes in Dubai, where Chevy revealed the ZR1, but today at Willow Springs some cool details emerge. To begin with, both cars are wearing the $2,995 ZTK package, just like the Dubai car. That means a high wing, Michelin Pilot Sport Cup 2 tires the size of oil barrels, and a light retuning of the Magnetic Ride Control. It's good for around 950 pounds of downforce at speed. "The increased downforce is noticeable at 50 mph," Juechter says, "though it's subtle. From 80-100 mph, it's more noticeable." More understatement. Without the ZTK, it's a few hundred pounds total. Picking a convertible means less downforce, as the top depowers the rear wing a bit. The front spoiler's endplates are removed to counterbalance that. Don't want a planted front and less planted rear, no sir.
"We treat aero as a safety issue," Juechter says. "When you have a car that can approach the speed of a light aircraft, you have to." And, in case you were wondering, the perfect way to set up a ZTK-optioned car is to hunker the front end down a half inch by cranking the transverse leaf spring adjusters and tipping the wing down to the full 5 degrees of its travel.
The cars pull in, and we slip into a HANS and open-face helmet, then into the Sparco bucket. Here's a tip from us to you: If you see something with 755 hp and a five-point harness inside, and the guy to your left was responsible for stress-testing the entire vehicle dynamics package, tighten up your belts. Then tighten them up some more. Barely able to breathe is a pretty good target. Michael Tung is the young, pleasant engineer next to me, about to unleash a lot of violence on Willow. We chat for a couple, then he lights off down the pit lane.
Despite the fact that the supercharger, nestled under a thin shaker hood, pokes right up out of the engine bay into the airspace in front of us, there's not much supercharger whine. Whatever might be there is absolutely drowned out by the bellow from the quad pipes, as the ZR1 squats down and hustles. There's some wheelspin, slight and irregular, as the Performance Traction Management (set at Sport 2) tries to translate twist into forward progress. It has its work cut out for it — the tires are brand new, nubbies and all, and cold. "I'll have to take it easy until they warm up," Tung says, doing nothing of the sort.
Heat, while great for tires, was a bugbear for the Z06. The ZR1 attempts to address this with a full 13 radiators (on automatic cars), including four new front auxiliary coolers, in order to reduce temps. There's a new lay-down transmission cooler up front, so overall there's a ton of piping going forward and back from the transaxle and differential. Juechter claims the automatic isn't itself to blame for the prior heating woes, explaining that the auto can hold revs higher than the manual, which causes higher underhood and intake air temps that could overwhelm the previous cars. The Z06's fixes included a new hood and more vents, but the ZR1's heat management system was validated to a higher level to prevent this issue in the first place — at 100 degrees with a full tank, versus 86 degrees and less fuel for the Z06. Will it help? It's too early to tell, but based on the time Juechter spent on cooling, it's a sore spot and we wouldn't bet against it.
Let's take a quick step back under the hood. Despite the different (and historically important) LT5 designation, this is more of a heavily revised LT4 than an entirely new motor. The block, rods, pistons, and heads are unchanged, but the crank is made of a stronger alloy and gets a new coating — lead, actually — to handle the extra power and take advantage of a new oil formulation. An 11-rib belt now runs the supercharger through a physically larger pulley, and now takes 110 horsepower to operate (versus 94 in the LT4).
Speaking of pulleys, compare the LT4 and LT5, and you'll instantly realize that there's potential for an smaller pulley to increase the LT5's output even more. Juechter senses what we're all thinking. "I want you to be sure that an overdrive pulley will void the warranty," he says, laughing a bit. He knows folks will still do it, but he won't guarantee what'll happen after that. The car will already run the quarter in the high 10s, and tops out at an SAE-certified 212.48 MPH, but "good enough" has never been good enough.
On track at Willow, it doesn't seem like the ZR1 needs any more power to keep its driver occupied. Tung's work has given him an abrupt, edgy driving style that unsettles the ZR1 a bit as it unweights coming downhill at certain points, but not quite to the point of four-wheel drifting. It's fascinating to see how someone who knows the car intimately, both theoretically and practically, makes it move. The ZR1 responds well to the rough treatment, but these are expert hands with hundreds or thousands of hours of seat time in the car. And a lot of the credit goes to the Michelins, which despite their expense have truly remarkable grip — and, Juechter says, surprising real-world treadwear.
Even more goes to the carbon ceramic brakes, which are simply ferocious. They're similar to the Z06's Brembos, but with extra heat-treatment and a high-temperature pad compound. But for every stab of the brakes, Tung hammers on the gas just as quickly. We blast for a second or so up a very short straight at the top of the Balcony before hauling down again and heading downhill. The ability to call up positive and negative Gs like this with just a dance on the pedals is mightily impressive. If you think an extra 105 hp and 65 lb-ft would turn the C7 Z06 into an unredeemable mess, think again. The ZR1 can put down the power, and it corners just like an angrier Z06.
We get four laps, and that's it. Short — too short — but more than we should get. GM doesn't like it when reviewers see the rough-hewn ancestors of their polished final products, let alone get seat time. The gamble here is that we won't care about the cosmetics when we're flopping against the harness, wowed by the sheer violence the LT5 can unleash. It's impressive, but admittedly an incomplete picture of the car.
The ones we'll drive next year will be too pretty to abuse this hard, and that's a shame. You know what? Give us the car we just flopped out of, leaning against its unpainted door. It's a weapon, more precise than you'd imagine given its ludicrous powerplant, exuding menace from every scrape and wound. It's never seen carnauba wax, won't end up with french fries under the seat, couldn't win a car show trophy if it was the only one there.
A fantasy, alas, given its fate. But the $119,995 ZR1 will be very real. Maybe if you ask nicely enough, GM's development engineers will break it in for you before delivery.