New Z/28 Rumbled Onto the Stage

At this spring’s New York auto show, the media at Chevrolet’s press conference expected the curtain to rise on the Camaro’s mild mid-cycle face lift, which had already been revealed on a morning TV squeal fest. But when a new Z/28 rumbled onto the stage, the jaded crowd was so shocked that it erupted in genuine applause. Here was the return of an American road-race icon, one that got its start as a homologation special for the SCCA’s Trans-Am series but had moldered through successive generations. Clearly, Chevy is trying to make up for lost time. The mission of this car is to help its owner set ­personal-best laps, and it comes sporting comprehensive power, handling, and weight-saving modifications—even outdoing the ZL1 in some regards. When it goes on sale later this year, the Z/28 will be even more expensive than the 580-hp ZL1, which stickers for $56,550. Here’s what’s under the skin:

chassis

In a departure from current fashion, the Z/28 goes down in wheel and tire size, from the 20 inchers on other V-8 Camaros to 19s. Mark Stielow, the Z/28’s engineering manager, explains that “the 19s are lighter, have less rotational inertia, and let us lower the car.” The special lightweight wheels are 11 inches wide in the front and shod with 305/30ZR-19 Pirelli P Zero Trofeo R tires all around. Chevy tells us that these are the widest tires mounted on the front of any production car. A streetable track tire, the Trofeo Rs have a tread-wear rating of 60 and are manufactured in the same plant as Pirelli’s F1 rubber.

The Z/28’s suspension geometry is unchanged from the Camaro SS 1LE, but the spring rates are about 20 percent stiffer and the car uses Multimatic monotube shocks with F1-style spool valves. Stielow says this technology provides greater freedom to independently tailor jounce and rebound settings for low- and high-speed suspension motions. Anti-roll-bar thicknesses are also up slightly over the 1LE’s, and the bars’ mounts are stiffer.

To both save weight and improve fade resistance, the Z/28 gets standard carbon-ceramic brakes that are larger and thicker than even the ZL1’s cast-iron brake rotors. The same TRW electrically assisted power steering used on other Camaros gets a revised calibration for the Z/28, and the car has Performance Traction Management, Chevrolet’s five-level stability-control system. Stielow claims that, with an overall ride height now lower by 1.3 inches and its very sticky rubber, the Z/28 will corner at 1.05 g.

powertrain

Displacing 7.0 liters (428 cubic inches), the dry-sump LS7 from the outgoing Corvette Z06 needed new exhaust manifolds and a relocated oil reservoir to fit in the Z/28’s engine bay; it gets stainless tri-Y headers dumping into a dual-mode exhaust system. Chevrolet promises the engine will produce more than 500 horsepower and 470 pound-feet of torque. For comparison, Ford’s Mustang Boss 302 makes 444 and 380, respectively.

The engine is coupled exclusively to a TR6060 six-speed manual with the same closely spaced gear ratios used in the 1LE package. Also as in the 1LE, the Z/28 uses a 3.91:1 final drive. Instead of the spring-loaded clutch pack used in the SS and ZL1, however, this car incorporates a Torsen limited-slip differential to provide a better blend of low-speed lockup with a more open high-speed action. As in the ZL1, the differential, transmission, and engine oil are all cooled by heat exchangers. Stielow promises that the car can burn a complete tank of fuel on the track without any vital fluid overheating.

weight reduction

The LS7 is about 90 pounds lighter than the supercharged LSA in the ZL1, and Chevrolet cut mass everywhere it could. The 19-inch wheels and tires save 42 pounds. The carbon-ceramic brakes drop 28. Cutting A/C (it can be optionally restored) saves another 20. The engineers had hoped to leave out the audio system, but keeping the radio and one door speaker was necessary to bleat mandatory seatbelt warnings. In addition, the Z gets a thinner rear window and a smaller battery. Trunk carpeting, a tire-inflator kit, and most of the sound insulation are gone. New foam eliminates the rear-seat frame and trunk pass-through, saving another nine pounds. Numerous other weight reductions make the Z/28 a claimed 300 pounds lighter than the ZL1.

aerodynamics

The most obvious visual cue identifying the Z/28 is its aero package. There’s a sizable front splitter, pronounced rocker-panel moldings, a rear diffuser, and a good-sized rear wing. Small front and rear fender-lip extensions cover the wide wheels and tires.

More than cosmetic, these changes develop net downforce, versus the Camaro SS, which has about 200 pounds of lift at 150 mph. Moreover, Stielow says that having more downforce in the rear than in the front enhances stability. There’s even an accessory Gurney flap that attaches to the rear wing for more.

Unfortunately, all of this extracts a drag penalty. While the standard Camaro has a Cd of about 0.35, rising to 0.39 in the ZL1, the Z/28’s is even higher. The aero appendages, the wide wheels, and the fender extensions add up to a car that “knocks a big hole in the air,” as Stielow puts it.

performance

Stielow wouldn’t release any performance claims for the new Z/28, but it’s safe to say that with stickier tires, better weight distribution, and a power-to-weight ratio only slightly worse than a ZL1’s, the Z/28 will accelerate almost as quickly. We’d estimate zero to 60 mph in about 4.2 seconds and a quarter-mile around 12.5 seconds. Expect top speed to be down from 180 to the low 170s. But on the racetrack, the Z/28 should be the quickest Camaro of them all. It has already lapped GM’s 2.9-mile Milford Road Course three seconds quicker than the ZL1.

- Courtesy of Car and Driver