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The Z/28, resurrected
Wicked is as wicked does.
By Chris Chilton April 7, 2014 / Photos by Jamey Price
They call it the "flow tie." In the pursuit of maximum cooling efficiency for the Z/28's 505-hp V8, someone realized that the Chevy's bow-tie-shaped grille badge was acting like a giant stop sign for airflow. Why not take it off? No, the General wouldn't like that. Instead, an engineer whipped out his humble Dremel and cut away the center of the emblem, leaving only the outline. A simple solution, maybe, but that "what if?" attitude sums up the Camaro engineers' approach to the whole Z/28 program, a skunkworks project to create a genuine, no-compromise track car and hang the expense.
Chevy knows the Z/28 will only appeal to a certain type of person, just as the original did in early 1967. Built to homologate the Camaro for the SCCA's new Trans-Am racing series, the first Z/28's party piece was a solid-lifter small-block that helped Mark Donohue run off with the championship in both '68 and '69. But the average customer found it hard to rationalize spending big on a piddly 302 when less money would buy GM's 396-cubic-inch Camaro, with almost 50 percent more torque.
Fast-forward half a century and history is repeating itself. Thus far, the fastest, most powerful, and most expensive Camaro you can buy has been the supercharged ZL1. 35 ponies stronger than a Nissan GT-R and half the price, capable of lapping the Nürburgring in 7 minutes, 41 seconds and ripping 12-second quarter-mile passes at the strip, the ZL1 seems the ultimate Camaro. Who'd spend 20 grand more for 13 percent less firepower?
"The kind of person who wants a car because it looks cool won't appreciate the Z/28," says the Camaro's chief engineer, Al Oppenheiser. "We said we'd only build another Z/28 if it was true to its historical origins. This is not a trailer car, but it's definitely optimized for the track."
No kidding. The list of component suppliers reads like a SEMA exhibitors map: brakes by Brembo, seats by Recaro, rods by Pankl, trick tires by Pirelli, shocks by Multimatic. Every one of the Z/28's 190 unique parts was chosen by answering one question: Will this make it go faster? They obviously do, because despite giving away 75 hp to the 580-hp ZL1, the Z/28 bests that car's impressive Nürburgring time by 3.9 seconds.
You only have to catch a glimpse of that front cowcatcher to know the Z/28 means business. Just one part of a suite of aerodynamic mods designed to reduce lift at track speed, that splitter can withstand 250 lbs of aero force, and it's echoed on the Z/28.R racer that made its debut at Daytona in January. Rocker-panel extensions guide air as it passes along the Z's flanks to a two-position Gurney flap, while an undertray delivers air to a rear diffuser. In total, they provided 150 lbs of positive downforce at 150 mph.
What you don't notice is the lightweight battery, that the rear window is made from thinner glass, that the rear seats have been slimmed down and the tire-inflation kit banished to help the pudgy Camaro shift some pounds. All told, the Z/28 weighs 22 lbs less than a Camaro SS 1LE and 224 lbs less than the ZL1, bringing the total mass down to a still-not-svelte 3856 lbs. Also gone as part of that diet are the heavy cast-iron rotors, replaced by carbon-ceramics, and the ZL1's burly differential, not needed here because the Z/28 is packing a very different kind of powertrain.
While the latest (C7) Corvette Z06 shifts to a supercharged 6.2-liter V8, dubbed LT4, the old Z06's LS7 engine finds a home under the Z/28's hood. The single most expensive device on the whole car, it weighs 64 lbs less than the ZL1's supercharged LSA V8, and it comes stuffed full of titanium rods and a forged steel crank. Those ingredients help produce a pushrod engine that'll happily hang out near its 7000-rpm redline as well as deliver the feel and response that only a large-displacement, naturally aspirated engine can.
From both an engineering and a philosophical standpoint, only one kind of transmission was deemed suitable to handle the engine's 505 hp and 481 lb-ft of twist. The good news is that it's the Tremec six-speed manual from the ZL1; the better news, that it's mated to a 3.91:1 rear end instead of the supercharged car's 3.73, to more efficiently make use of the LS7's torque curve. Zero to 60 mph took us 4.0 seconds on a less than ideal surface, putting the car ferociously close to its ZL1 brother.
But judging a track car by its spec sheet is like reviewing an album based on the liner notes. So we've come to Alabama's Barber Motorsports Park, site of the Z/28's media launch, to try the car ourselves. While too technical and compact a track for us to feel out the car's high-speed aero prowess, there are enough elevation changes and transitions to uncover any car pretending to be something it's not.
Earlier, we did a handful of familiarization laps in a Camaro SS with the 1LE option, a handling package that turns the coupe from ho-hum to ho-ho. But the Z/28 is different almost beyond recognition.
It's obvious immediately. You feel it in the measured precision of the steering and the tautness of the damping that checks every minute body motion. Chevy says the car's bolt-on wheel-arch lips are there to promote stability, but they're also preserving the modesty of some humongous tires. The rear 305/30R-19 Pirellis are an inch smaller than those on the ZL1, but instead of that car's 285/35R-20 fronts, the Z/28 gets 305s at the nose as well as out back. That's an outrageous amount of tire for a front axle to deal with, 10 millimeters wider than the rear rubber fitted to a Ferrari 458. Did engineers worry about winding up with the steering sensitivity of an autistic Audi?
"This was a big debate," says GM's Adam Dean, the lunatic responsible for that 7:37 time on a partially wet Nordschleife. "Of course, the worry is that you'll have tramlining and a loss of sensitivity. I think we're close to that limit, but we have to run a big tire because we don't benefit from a camber change in cornering with a strut-type front suspension."
Translation: Everything's a compromise. And the front rubber is beyond monstrous, and monstrously grippy, so stop complaining.
The tires in question are Pirelli P Zero Trofeo Rs, summer track rubber that frightens in the wet but clings to dry pavement with prejudice. They take a couple of laps to warm up, while the oil pumping through the LS7's dry-sump system does the same. By lap three, the turn-in understeer has gone and the full extent of the car's staggering grip is revealed.
We're told the Z/28 can pull a mighty 1.5 g under braking, thanks in part to four-wheel carbon-ceramic brakes that are as impressive for their pedal feel (a common carbon-brake failing) as their total refusal to fade. But here's the crazy bit: The Z has so much stick that the 19-inch wheels are media blasted to add texture, because they were found to be slipping within the tires during testing. Not by a couple of degrees, or even 10, as Chevy first thought, but a whopping 370.
The electric steering is neither particularly quick by modern standards nor the last word in feel, but it relays all the important signals when you near the outer limits, remaining just on the manageable side of meaty, the weight falling off, tugging at your wrists ever so slightly as you push. Lower-control-arm link bushings stiffened by 50 percent lend a welcome improvement in precision around and just off the straight-ahead.
It's a well-judged setup, but it's the damping that steals the show. Instead of the computer-controlled, magnetorheological shocks fitted to the ZL1, the Z/28 gets a fixed-rate damping system designed to work with springs that are 85 percent stiffer in the front and 65 percent stiffer in the rear than on the SS. A pair of spool valves in each shock allows superior control of oil flow and independent compression and rebound tuning. Normally seen in top-flight motorsport, the only other road car to use dampers like these has been Aston Martin's $1.75-million One-77.
Predictably, they're awesome. You never forget that you're hauling nearly 4000 lbs of car, but the Z/28 manages its weight so well in braking and through transitions that you find yourself taking liberties. Turning in on the brakes late to point the nose. Climbing back on the power early to do the same. I can't think of another track-focused car with this much power and so few vices, so much stability. Whatever your own level of performance, the Z/28 has something to offer, nothing you need fear.
A five-stage Performance Traction Management (PTM) stability-control system is on hand to spare any novice blushes, but the first two settings would rather you just park the Z/28 in the paddock, and even the third feels like a sop to the tires' propensity to give up in the face of precipitation. No, modes four and five are where it's at. Four when the track is damp and you want the comfort of both throttle and brake intervention. Five when you want to go as fast as it's physically possible to go and just need help with the gas. Dean's 'Ring heroics were achieved with the stability system in mode 5. Switch it off altogether and you'll almost certainly go slower.
Fortunately, PTM's subtle nature and the combination of sticky rubber and a new Torsen limited-slip differential means the system never dominates the driving experience. The diff stays relatively open on the approach to a corner to kill understeer, the Z relying instead on its ABS for stability. But hit the throttle at the apex and the LSD hooks up quicker than high schoolers after prom. Chevy's guys say the diff is worth 0.7 second around GM's Milford proving ground and that the whole Z/28 package helps the Camaro lap 5.34 seconds faster than the brilliant last-generation Ford Mustang Boss 302 Laguna Seca—in some turns, achieving speeds an absurd 10 mph higher.
The Z/28's light, short-throw shifter also bests the Boss's, its gate precise enough to make wrong slotting inexcusable. Unlike the latest Corvette, there's no La-Z-Boy rev-matching software on hand to make you look like a hero. If you want to get downshifts right—and on a circuit, if you want to stay out of the sand, you really ought to—you need to do it the old-fashioned way, rolling on that throttle and hearing the growl from what must still rank as one of the best engines to come from America.
So it's a shame that GM's fear of unintended acceleration has the pedal spacing favoring snowshoes over Sparco boots. And when you do manage to connect with the throttle, there's just the tiniest smidgen of slack, engineered in to dial out driveline shunt at the behest of the GM passenger-car guys and against the wishes of the Z/28 team's racers.
But when we leave Barber and venture out on the road, it seems that Oppenheiser is being modest about the Z/28's streetability. The lack of trunk insulation is apparent in the increased tire roar, and those fat front Pirellis like to settle into the grooves in the pavement. But the ride is bearable, the big LS7 tractable, the clutch light. You probably wouldn't want to drive it every day, but you could, in which case you'd want to add a little weight with the optional radio and air conditioning.
Of course, doing so makes a pricey car even less palatable. At $75,000, the Z/28 is $20,000 more expensive than either the Camaro ZL1 or the new Corvette Stingray, brilliant cars both. Worse still, BMW's new M3 will undercut it by at least $10,000. But none are so focused as this.
Stuck in traffic, gazing at the sub-Korean plastic of the center console, the Z/28 feels as convincing a $75,000 car as a Toyota Yaris. But on a track like Barber, it feels invincible. Not as exciting or engaging as the $130,000 Porsche 911 GT3 I jumped into for context days later—arguably the benchmark street racer—but money well spent, all the same.
If you want a quick car, there are better buys, better Camaros. A ZL1 makes more sense for all but a few hardy souls. But for the guy who recognizes the difference between a fast car and one whose every fiber has been optimized in the pursuit of total performance, this Z/28, much like the original, is the real deal.