Z/28 Preview – The Ultimate Track Camaro
It’s been a busy couple of years for GM’s performance division engineers – consider all the droolworthy cars now in showrooms or on the way, and we think you’ll agree. Between the new C7 Corvette Stingray, the new-to-us Chevy SS, and the ZL1 and 1LE Camaros, they’ve provided enthusiasts with a lot of different choices when it comes to fast transportation.
And now, there’s the Z/28, which in many ways is even more hard-edged than the outgoing C6 Z06 in terms of being a car built specifically for the track. It shares the Z06′s LS7 powerplant and retains the same official 505 crank horsepower rating, but detail changes have increased peak torque from 475 pound-feet to 481, and broadened the area under the curve.
Of course, the main internet keyboard warrior complaint about the 5th Gen platform has been its considerable curb weight; the Camaro is a sizable car, and the ever-increasing weight burden of crashworthiness standards and additional “content” have extracted a performance penalty even the best powertrain and suspension will have to overcome in order to achieve lap time reductions.
Chevy calls their program to reverse that weight creep “lightweighting,” and goes as far as to say that they took everything out of the Z/28 that didn’t make it go faster or was required by law. Air conditioning is an option; check that box and you also get more than the one speaker required to transmit the “click” noise the turn signal indicator makes. Everywhere except for New Hampshire and Rhode Island, the Z/28 will come sans-tire-inflation kit (those states have a legal requirement to include it), the rear glass is 0.3mm thinner, trunk trim and acoustic insulation are gone, and even the floor mats are deleted.
But the big savings come from the featherweight wheel and tire package, the carbon ceramic brakes, and the aforementioned LS7 powerplant. All told, the Z/28 is some 300 pounds lighter than the ZL1, and 80-100 less than the naturally-aspirated Camaro SS. This still isn’t a light car by an absolute standard, tipping the scales at 3,837 pounds, but with a 52/48 weight distribution and a power to weight ratio of 7.59 pounds per pony, it’s about as good as a full-interior 5th Gen Camaro is going to get.
Last of the LS7
The naturally aspirated, 427 cubic inch LS7 powerplant differs slightly from the version seen in the Corvette Z06. It retains the dry sump oiling system, but gets a pair of 3-2-1 exhaust manifolds made possible by the greater real estate between the Camaro’s fenders. An open element air filter, developed in conjunction with K&N, is also prominent under the hood.
Like all previous LS7 engines, the Z/28′s power plant will be largely hand-assembled at the recently-relocated Performance Build Center adjacent to the Corvette production line in Bowling Green, Kentucky. That will allow the PBC’s capacity to be utilized effectively until high-performance versions of the C7 come online in subsequent model years.
Because it uses a version of the same engine management system in previous Corvettes, the Z/28 won’t have the trick rev-matching feature the C7′s LT1 employs, but this car’s target audience should be well-versed in heel and toe downshifts themselves.
Where the Rubber Meets the Road
While the Z/28 uses identical 305/30ZR19 Pirelli Trofeo R tires on all four corners (incidentally, the widest front tire on any production car), the Z/28-specific rear wheels are a half-inch wider in back, at 11.5 inches. That subtle change in sidewall geometry was designed to enhance rear handling at the limit of traction.
Those wheels frame massive Brembo carbon-ceramic brake rotors and monoblock 6 piston calipers up front, and 4-piston in back, designed for repeated high-speed stops. The front rotors measure 394mm in diameter and 36mm thick, and in a testament to the car’s grip balance, the rears are barely smaller at 390 by 32. The pad compound has been formulated to offer good cold bite as well as carbon’s typical fade resistance, alleviating a typical issue with race-style brake systems.
In an interesting technical note, the ABS is programmed to “tickle” the calipers with a bit of pressure to fight pad knock-back, the phenomenon where the slight, unavoidable lateral motion of the rotors during hard cornering causes the pads to retreat slightly into the calipers. Knock-back can lead to a nasty surprise at the end of a long straight when the brake pedal needs far more travel to return the pads to intimate contact with the rotors, and the ABS strategy is a clever way to help keep braking performance consistent.
Suspension of Disbelief
One area where the Z/28 doesn’t employ on-board intelligence to enhance performance is in the suspension dampers. Where the ZL1 utilizes a multiple-mode magnetic ride control system, the Z/28 employs Multimatic’s sophisticated but non-adjustable Dynamic Suspension Spool Valve dampers on all four corners.
Why the seeming downgrade in kit? Easy – the Z/28 is designed with one mission in mind, and if it didn’t lower track times, it got left on the garage floor. The DSSV dampers are precisely tailored to the suspension of this Camaro, and any adjustment to their rebound or compression curves would simply be a move in the wrong direction from the ideal determined through countless test laps. Some potential owners might grumble about the lack of knobs to turn, but let’s face it – unless you’re smarter and have more experience with this car than the GM chassis engineers, anything you do to change the suspension will just be flat-out wrong.
Don’t get the idea that the Z/28 doesn’t take advantage of the power of onboard computation when it comes to the suspension, though. The ZL1′s wheel position sensors are still there to feed data back to the powertrain control module and keep it well-informed about what the suspension is doing. It’s smart enough to know the difference between a wheel that’s extended due to cornering, and one that’s at full droop because you’ve just encountered one of the three spots on the Nurburgring where the Z/28 briefly gets airborne on a good lap, for instance.
Going with the Flow
Speaking of airborne, a number of changes in aerodynamics give the Z/28 440 pounds more downforce than an SS at 150 miles an hour. The front splitter, considerably different from the ZL1′s, is said to be able to withstand a 250 pound load, and a large functional hood vent relieves pressure in the engine bay at speed while helping the paired puller/pusher fans move air through the radiator and separate oil cooler behind the grill.
A ZL1-spec undertray cleans up airflow beneath the front half of the car, while fender flares, Gurney lips, and small underslung air dams guide flow around the wide and widely-spaced tires. At the tail end, a bespoke spoiler with an optional adjustable wickerbill kills lift and keeps the car balanced.
So What’s It Like?
In our time at Milford with the Z/28, we got a chance to ride along with GM’s development drivers to experience the full potential of the car. Note that we didn’t say “drive” – while the Z/28 isn’t ill-mannered, and will do just fine on the street, even approaching its limits will require a higher level of skill than the journalist pool average. We were glad to get a chauffeured tour of the Milford test track to really be able to appreciate what the car was doing.
Around the 2.9 mile test loop, Chevy compared the Z/28 to some interesting benchmarks – its siblings, the 1LE and ZL1, and its arch enemies, the Mustang GT500 and Boss 302 Laguna Seca. Interestingly, the car with the most power, the GT500, also posted the slowest lap time, clocking a 1:59.97. The Laguna Seca did a bit better, running a 1:59.05, followed by the 1LE at 1:58.85. Despite the intensely technical nature of the test track, the ZL1 was still able to use its superior horsepower compared to the 1LE to run a faster 1:56.58, but it was the Z/28 that delivered the best time at a mere 1:53.71.
Is the Z/28 a race car for everyone? We’re told it will price out above the ZL1 when it hits showrooms early next year, so it’s not going to be a common sight on public roads. Nor should it be; this is clearly a track toy that just happens to be completely street legal with room for four (as long as two of them are small, and you hate them anyway). Chevy has hit the mark with the Z/28, though it might not be the mark your average Camaro fan would have aimed for in the first place.
Some will say it goes too far, while others will say it doesn’t go too far enough. We think that Chevy has split the difference neatly, with a Camaro that isn’t so hardcore that it will revolutionize the way rich guys run out of talent, but will still provide a level of performance so high that most owners will really have to step up to reach it.