Chevy's torque monster Corvette Z06 joins 400-hp, sub 4-second 0-60 mph club
In the grand scheme of things automotive, it might not be earth-shattering news. But for performance-car aficionados, particularly those of the Corvette persuasion, it is a momentous occasion.
The 2002 Corvette Z06 will have more than 400 horsepower — 405 to be exact. And 400 lb-ft of torque. (At 6,000 and 4,800 rpm, respectively.) That's 405 SAE net horsepower. Not the pre-' 72 gross figures that inflated muscle-car power ratings beyond what they really were.
That makes the new Z06, on comparable terms, the most powerful Corvette ever — the equal of the DOHC LT5-powered ZR1, available briefly in the fourth-generation cars.
It is also the fastest Vette yet.
The 2001 Z06 was touted as the fastest ever, so 20 more horsepower is just icing on the cake. But what sweet icing it is.
GM claims it is capable of a 3.9-second 0-to-60 mph time, which means about 4 seconds flat from 0-to-100 km/h. That's 1/10 of a second quicker than last year's car — and well into supercar territory, where Ferraris and Porsches play. On the drag-strip, GM claims 12.4 seconds at 116 mph (187 km/h) — 0.2 seconds and 2 mph (3 km/h) better than the 2001 Z06.
GM turned us loose on an autocross circuit at Irwindale Speedway, just outside Los Angeles, to get a seat-of-the-pants feel for those 20 new horses. In truth, without a 2001 car available for direct comparison, I can't say I noticed the difference. What I can say is, "What a ride!" The 400-plus number was a challenge, says Corvette's now legendary engineer, Dave Hill — as was the chance to equal the LT5/ZR1's output.
The magnitude of that challenge might not be immediately apparent, given the Corvette engine's substantial displacement of 5.7 litres. Several small, high-winding engines now produce in excess of 100 hp per litre.
But the bigger an engine gets, the harder it is to match those specific outputs (hp/L), even with the same technologies. The smaller engines are double-overhead-cam designs, with four valves per cylinder, variable valve timing and variable intake systems.
The 5.7-litre LT5 was also a DOHC four-valve design that pushed the power envelope.
The LS6 engine in the Z06 is a pushrod-operated, two-valve configuration with neither variable valve timing nor a variable intake system — and it has to satisfy National Low Emission Vehicle (NLEV) standards. That is what makes the achievement of GM's powertrain engineers remarkable.
They did it through painstaking attention to every detail.
Hollow-stem valves, a higher-lift camshaft, low-restriction mass-airflow sensor and air cleaner, and a higher-flow exhaust system contribute to better breathing, which results in increased torque. More torque means increased power.
In fact, says Hill, "When you hear customers talking about wanting more power, what they really mean is they want more torque. It's torque that gets you going, whether launching from a standstill, or accelerating out of a corner." Torque is what the Z06 is all about — just touching the throttle on the tight autocross course was like igniting a rocket.
Which brings into play the other significant feature of not just the Z06, but all new Corvettes — its second-generation Active Handling System.
Like other dynamics control systems, this one senses such inputs as throttle, brake and steering angle, matches them with yaw rate to determine if the car is deviating from the desired course, and takes corrective action with engine and brake intervention to keep things under control.
It's an effective safety system for everyday driving, but can get in the way if you are trying to cut a fast lap on a slalom course. Turning off the system is an option, but all that torque can easily become overwhelming.
The Vette's answer is its Competitive Mode setting.
Hold the appropriate button down for a few seconds and, instead of switching off or on, the system will engage an intermediate mode.
When fully on, Active Handling features dynamic rear brake proportioning to prevent rear lock-up, rear brake stability control to assist the driver in maintaining directional control under light braking or hard acceleration, and an integrated traction control system, in addition to conventional ABS.
In Competitive Mode, the traction control system is disengaged, letting you "hang the tail out" just enough to have some fun, without sacrificing the system's other benefits.
GM says its objective for the Corvette is to make it the best performance value on the road.
From where I sit — behind the wheel of a 2002 Z06 — it's mission accomplished, and then some.