08-20-2008, 12:14 AM #1
ZR1 Drive Reflects Tech Evolution on the Road: Mechanic's Diary
ZR1 Drive Reflects Tech Evolution on the Road: Mechanic's Diary
After declaring the 2009 Corvette ZR1 "a benchmark for American muscle," PM's senior automotive editor explains in his biweekly online column how the new Vette's 600 horses get the power to the ground—and why you don't need to be a race-car driver to take her to the limit.
By Mike Allen, Popular Mechanic
Photograph by Ed Kukla
Published on: August 20, 2008
MILFORD, Mich. — When I was driving the new Corvette ZR1 recently, the most shocking aspect wasn’t actually the 638-hp supercharged V8. No, it’s the way Chevrolet manages to get all that power to the ground in a safe, controllable manner. The ZR1 is one of the fastest, most powerful cars in production. But it’s so well engineered that I could let my mother drag-race a Dodge Viper in one ... and she’d probably win. There have been plenty of terrifyingly quick cars on the road over the years—some that were easy to drive quickly, others that were, well, more or less widow makers (or at least not-at-all fun to handle at the limit).
One of the most notorious was the early 1970s Porsche 930 Turbo, back before anybody really understood turbo lag. The light switch throttle response, heavy rear weight bias and skinny (by today’s standards) tires would have the Turbo off the edge of the track amd into the gravel trap following the smallest inattention to the task at hand. Scary? Yes, sir.
A lot of muscle cars—especially ones with heavy, big-block motors and skinny bias-ply tires—were absolutely amazing at doing one thing: rocketing from one traffic light to the next on Detroit’s Woodward Avenue. The loop went from the Totem Pole Drive-in to Ted’s in Bloomfield Hills, and I spent the formative part of my automotive youth soaking up that scene. But driving one of those beasts would take all the color out of your face the first time you came up to a corner and tried to turn. Come in too hot, and you’d end up on the side of the road facing backwards. The brakes were bad, too—lockup was just one prod of the pedal away.
In the late 1980s, I tested a pair of turbocharged monsters. It was a great supercar battle: the Buick GNX vs. the Callaway Corvette. The Buick had a single ceramic-impeller, turbo-fed V6, while the Callaway boasted a pair of turbos, one on each side of the 350 V8. The goliath GNX also used an automatic transmission, against the Vette’s 5-speed. Launching the Chevy at the start line of Milan Dragway wasn’t easy—there seemed to be almost no sweet spot between burning the tires into a smoky haze or bogging the engine for a turtle-like launch. The 60-ft. times varied all over the map, even though the trap speeds were consistently amazing. The Buick was exactly the opposite: stage shallow, hold the brakes with your left foot, tach it up to 2600 rpm, sidestep the brakes, and floor the throttle when you saw the tree go yellow. Ultimately, Buick won the shootout, and Reeves Callaway himself called me the next week with an attitude. Oh, well.
Once, I tested one of those 427 Cobra replicas. Neat? Oh, yeah. But it wouldn’t go straight anytime the throttle was more than 1 in. depressed. The back tires would simply skate sideways, sliding down the fall line like an escaping snowboard. I cut that test short after a couple of white-knuckeled laps. Maybe there was a good reason that most of my racing career was spent behind the wheel of small cars with smaller engines. Maybe the lap times were a couple seconds off the most powerful cars, but the time behind the wheel was definitely better. And I didn’t spend most of the back straightway trying to remember if I had mailed in that life insurance premium or not.
So why the trip to yesteryear when I’m talking about the new ZR1 Corvette? Simple. All the power in the world won’t do you any good if you can’t put it down on the ground. I learned that jumping motocross bikes. The longer you were in the air, the longer it took before you could accelerate again. The faster car is the one that can get the power down coming off a corner. And in drag racing, excess tire smoke equals disappointing time slips.
The quantum leap in performance and horsepower from cars like the ZR1 really wouldn’t be as impressive if there weren’t commensurate increase in chassis technology. And I’m talking about the obverse and reverse of the same coin—traction control and yaw control. Since virtually every vehicle made has antilock brakes, it’s cheap and easy to add traction control to the engine management firmware. Yaw control, which keeps the vehicle pointed the direction the driver intends, requires only additional yaw-rate and steering wheel sensors.
Yes, it’s still possible to put your expensive German sports car—or your small American SUV, for that matter—into the hedge if you approach a corner faster than the laws of physics will allow. But brake-based yaw control, called various things from stability management to “The Hand of God,” essentially grabs your rear bumper and repositions the vehicle, so you at least have a chance to negotiate that slushy freeway exit … between the guardrails.
The technology of these systems continues to improve. I drove GM’s first prototype, installed on a nondescript FWD sedan, at Transportation Research Center in Ohio more than 15 years ago. It helped keep you in a straight line when braking on the split-mu skid pad. However, you could outfox the thing and still get into a slide. But it was certainly impressive at the time. And the German car companies were all over this technology right away.
Early Mercedes-Benz cars with traction control were downright annoying to drive. Almost any maneuver on slippery pavement that promulgated wheel spin resulted in the loss of throttle control for a good three seconds. It destroyed the ability to actually drive the car into a corner with any slip angle. It was like being punished. Later versions, from all manufacturers have become consistently less aggressive, and more sophisticated.
But Corvettes—at least since the C5—have nailed It. Whether in a new ZR1 or a standard model, it gives the driver control, letting you turn the traction control off completely, making smoky burnouts possible and big grins easy. The next step past that is a recalibration of the yaw control, allowing an experienced driver to actually drive the car with only that “Hand Of God” saving your hide if a spin is inevitable. And even then, the response from the system is swift and muted. It’s a rare driver indeed—and I’m not one of them—who can improve his lap times by turning the system completely off.
I could hand the keys to a new ZR1 to just about any responsible adult, and feel fairly safe they’d get across country in one piece. I can’t imagine doing that with a Cobra or a 1960s L88 big-block 427 Corvette. In this case, times have changed ... for the better.