From the Archive: 1993 Chevrolet Corvette ZR-1 Test

From the May 1993 issue of Car and Driver.

Travelers out west are familiar with signs that warn “DO NOT DRIVE INTO SMOKE.” One of these signs should be bolted to the convex fiberglass rump of the 1993 ZR-1. At least while you’re conducting 0-to-60 accel tests—purely in the name of science, of course—with the traction control disengaged. I mean, you wouldn’t think that any engine short of something concocted by John Force could so instantly transform two twelve-inch strips of gooey Eagle GS­-C into a dense and acrid wall of smoke the color of Flint Ink’s Butterfinger blue. But this is what 405 horsepower can do for you. Also, this is what 405 horsepower can do for your insurance agent’s complexion.

But never mind that. The big news is that the ZR-1 finally offers the power it should have generated when the engine was introduced in 1989. Jim Minneker, the Corvette Group’s powertrain manager, and the people at MerCruiser in Stillwater, Oklahoma, have extracted another 30 horsepressure, raising the ante to 405, a figure that always evokes a gasp and a “Holy smokes!” or two when it is divulged to onlookers. (If that doesn’t do it, mention casually that second gear is good for 84 mph.) Torque is up, too, but by only 15 pound-feet, raising the count to a not-insubstantial 385 pound-feet at 5200 rpm.

Twenty of those horses were obtained when the plenum and the intake runners were polished and, as Minneker says, “generally opened up.” Moreover, says an insider, “finally a little bit of porting and matching is going on—so few ZR-1s are being sold [4600 to date] that there’s time.” The valve inserts now have what is known as a “three-face cut” for less turbulent air/fuel flow—a trick plagiarized from hot-rodders with black gunk permanently clogged under their fingernails. And a new spacer ensures closer alignment of the ports and the injector manifold itself. In addition, the LT5 is filled with platinum-­tipped plugs, which are hotter than last year’s, and the engine glides exclusively on synthetic Mobil 1.

The remaining 10 hp, says Minneker, resulted from a reduction in backpressure. GM seems a little embarrassed by this, but the 2.25-inch tubes in the resonators of last year’s LT1 were flowing more freely than the 1.75-inch versions strapped to the ZR-1. The King of the Hill now wears its less beastly brother’s resonators and breathe a little easier in the bargain.

C/D readers may recall that our favorite Corvette aftermarket fiddler, John Lingenfelter, went through the same ZR-1 cleanup program, perhaps more conscientiously, in July of 1991. He came up with a bonus of 80 horsepower, bringing the total to “an easy 455.” Since then, he says, “I’ve worked harder and am seeing as much as 485 horsepower. There’s a ton of untapped potential in a ZR-1.” (If you want more of this untapped stuff, drive your ZR-1 to Lingenfelter’s in Decatur, Indiana, and hand him $13,500.)

In any event, the new-and-improved 1993 ZR-1 is every bit as docile around town as last year’s, which is to say it is like driving any other current Corvette. In fact, we’re now even less aware of the secondary inlet port banging open. What’s more, in the middle of this test, the firmament over Michigan divested itself of six inches of snow, slush, and ice. You wouldn’t expect tires that look as though they’ve been stolen from Steve Kinser’s sprint car to work on an ice rink. But when they’re combined with the Corvette’s effective traction control (whose technical, but ridiculous, name is “Acceleration Slip Regulation”), the ZR-1 does as well as a 405-horsepower Zamboni. Trust us, this is a claim that cannot be made for either a Mazda RX-7 or a Toyota MR2 Turbo.

So how fast is 405 horsepower on dry pavement?

With a smoke-warning sign hanging on the ZR-1’s tail, 60 mph is yours in 4.7 seconds. (The first ZR-1 we ever tested hit 60 in 4.6 seconds, though that’s mostly testimony to the unpredictable tolerance with which MerCruiser tended to assemble engines. Two subsequent ZR-1s tackled 60 in an identical 4.9 seconds—a figure we accepted as the norm.)

The 1993 ZR-1 carries on through the quarter-mile in 13.1 seconds at 111 mph, then eventually attains 179 mph—6 mph beyond the average top speed of previous ZR-1s. On the way there, the huge inch-­high speedometer digits flick past like bicycle spokes fanning a baseball card. Not in individual units but in clumps: 3 mph here, 5 mph there. Skidpad grip is up, too, from a past ZR-1 average of 0.88 g to a leech-like 0.92 g. Thank you, Mr. Goodyear.

In fact, the 1993 ZR-1’s accelerative résumé, all the way from the 7-Eleven lot to top speed, is almost identical to the limited-production Porsche 911 Turbo S2’s—”the fastest Porsche in the land.” Which, we should point out, is more expensive by an amount that permits you to purchase both this ZR-1 and, say, a Lexus GS300 for those days when only Interstating is on the menu.

The new ZR-1’s speed makes even General Motors fidget. On its official spec sheet, under the “Performance” heading, Chevrolet lists EPA mileage and drag coefficient (0.33, if you’re wondering), then moves right on, uttering nary a hint that this car surpasses the highest U.S.-legal speed by, ah, 114 mph.

To nail 60 mph sooner and less expensively, you’ll have to buy a $35,660 LT1 and haul it to Lingenfelter, who’ll lay his magical smog-legal “383 Kit” on the thing. This will raise your investment to $50,000 but will launch you to 60 mph a half-second sooner than a ZR-1 can. Which has nothing to do with production cars, of course, but neither does Detroit Mayor Coleman Young, a topic that comes up in conversation almost as often.

We’ve come to expect eyeball-popping brakes on Corvettes. The new ZR-1, with its frying-pan thirteen-inch front rotors, does not disappoint. No kidding: from 70 mph, if you dropkick the Bosch ABS IIU into maximum grab, it’s like some sort of amusement-park ride. Loose items slam into the dash, the passenger’s seatback lunges a half-inch, your ears feel as if they may fold forward and cover your eyes, and the car comes to rest in 161 feet. Some feat for a 3500-pounder. Eight feet better than a Ferrari 512TR, in fact. To regularly equal this sort of braking, shift your posterior and wallet to cars assembled in Zuffenhausen—which, as we all know, is not as easy to pronounce as Bowling Green.

The ZR-1 you see here was kitted out with a 40th Anniversary package, which you can order on any Corvette (assuming you have an extra $1455 earmarked for general lifestyle enhancement, although it’s a no-cost option on the ZR-1). The deal includes exclusive “Ruby Red” metallic paint, matching wheel hubs, four chrome emblems (with which we could gladly dispense), special embroidery on each headrest (right where it gets smeared by Vitalis), and Ruby Red leather seats.

Okay, okay. The ZR-1’s clutch is still Caterpillar heavy, and the computer-assisted shift that occurs at low speeds to force a first-to-fourth selection is still an irritating intrusion. Also, no one can distinguish your chic ZR-1 from Billy Ray’s base LT1, the doorsill remains a hurdle plucked right from a 100-meter event, the bar-graph fuel gauge is as easily discernible as a 1040 form, the hood still goes all epileptic over railroad tracks, and, at only 3200 miles, our ZR-1’s glovebox door mimicked the sound of Leona Helmsley’s fingernails dragging across a blackboard.

Yet, as our editor, Csaba Csere—a man who poses questions that would embarrass Larry King—put it: “Name another production car this reliable and cheap that you could drive as happily at 179 mph.”

Apart from the toe of my shoe carving interesting Rorschach patterns in the office carpet, there was silence.

The Latest in Door-Locking Magic

Power locks have become common­place, and remote-control unlock­ing devices have lost their zoot. Now, Chevrolet introduces the latest thing in trick openers—the world’s first Passive Keyless Entry system (PKE). It is now possible to run through a blizzard, arms full of groceries and mittens on hands, and have your Corvette magically unlock itself as you approach.

Here’s how it works. Step within about six feet of the car while carrying your keys—even in a pocket or a purse—and the system disarms the alarm and unlocks either the driver’s door or both doors, depending on the mode you have selected. To lock up, just walk out of that range; five seconds later the car locks, rearms the alarm, and confirms the maneuver with a single toot of the horn (unless the key has been left in the ignition).

The hardware behind this magic includes a transmitter in the key fob that broadcasts a very low frequency signal—120 kHz, versus 300 MHz for a standard remote entry system—to two antennas, one located in the driver’s door and one near the rear hatch (or passenger door in a convert­ible). One million transmitter codes ensure security. When the transmitter in the key fob comes into range, it acti­vates the system by completing an elec­tromagnetic field, somewhat like the coupling of two windings in a trans­former. So PKE is entirely different than today’s radio or infrared remote systems.

To prolong its battery life, the key fob only transmits a signal while in motion, which can cause a problem for those who leave keys sitting on a seat in the car. When the transmitter shuts off (after 30 seconds without motion), the car presumes it is out of range and locks the car. With luck, jiggling the car can reactivate the transmitter and unlock the doors, but Chevy warns against relying on this approach.

The PKE draws about one milliamp of current from the vehicle battery at all times—about as much as the clock and the radio station preset memory draw—so Chevy recommends that you disconnect the battery before storing the car for long periods.

There are no current plans to extend PKE to other models. But because the system adds considerable convenience for about $145, we expect it to go the way of power locks and wind up in the majority of high-line cars. —Frank Markus