Looking Back at the 1990 Chevrolet Corvette ZR-1


They get no respect, those American-made sports cars. Particularly in Europe, where performance, handling, and exclusivity-not catchy ad slogans-determine the actual meaning of a car’s worth. Sure, one suspects it’s an affectation-like wearing denims with the Giorgio Armani jacket, even though the Swiss buy Detroit-built sedans and wagons. Truth is, most European automotive enthusiasts have little regard for almost any automobile America has produced in recent memory.

However with the introduction of the Corvette ZR-1-on the 1989 Geneva Auto Show, of all places-that attitude is going to change.

You may know the ZR-1 as the King of the Hill, which is what this Super Vette was com­monly called when the program was barely more than a rumor. For reasons known only to GM brass, that name is now taboo. Our guess is that Chevy, who’s seeking international recog­nition, found the name too domestic, not to mention too long, for any car badge-and untranslatable (Le mi de la monlagne? Non. Der Konig am Hiigel? Nein ). Better to ensure that it staysshort and easy, and sweet. And alphanumeric so as to capital­ize on its similarity to many other European exotics such as the BMW M1 and Ferrari F40.

Exotic? Dave McLellan, Corvette Chief Engi­neer since 1975, prefers you not call it that. Exotics are outrageously styled, astronomically expensive, highly tem­peramental, limited-production automobiles that happen to be often racers masquerading as road cars, as McLellan sees it.

Sure they’re fast (180 mph is median speed for most Bahnburners). But should you be going cross-continent, you would consider the Merc or perhaps the Bimmer. Up to now. You see, the ZR-1, one of the fastest sports cars in the world, is also blessed with superior handling and brak­ing. Yet it is the most civilized and technologi­cally advanced and the least expensive super­ car in production because it is still a Corvette.

The ZR-1 looks like a Corvette. There’s that unmistakable shape however with a notable differ­ence: The bodywork widens beginning in the leading fringe of the doors and culminates in a tail that is 3 inches broader than the normal Vette’s-to accommodate the hefty P3 I5/ 35ZR-17 Goodyear Eagle Gatorbacks made particularly for this car. The soft, polyurethane end cap differs too, convex rather than concave with square versus round tail lights and a small red ZR-1 badge that graces the reduced right corner. Chevy 3 studio chief John Cafaro describes the Vette’s physique as “muscular,” and this is especially evident in the ZR-1, which shares the same front end (front wheels and tires, too) with all the conventional Corvette, the so-called L98. Another notable distinction between the ZR and L98-1 is weight. Heftier en­gine, tires and bodywork etc. make your Super Vette some 200 lbs heavier than an L98 coupe.

As a Corvette, the ZR-1 also shares the Bosch ABS II anti-lock braking, hybridized Z51 suspension, and FX3 Selective Ride Con­trol packages together with the L98. Ditto the UJ6 Low-Tire-Pressure Warning System, which combined with the above is standard around the Chevy flag­ship. Although the Bosch ABS and also the suspension need no explaining (it’s simply the Z51 setup with softer springs and anti-roll bars) and the UJ6 is self-explanatory (a light on the cen­ter console tells you if a tire is going flat), FX3 does call for a brief description.

READ: The Cobra vs. Corvette showdown from 1963

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Basically, this Bilstein-engineered system, which borrows from Porsche 959 and Lotus Formula 1 technology, utilizes a gas-over-oil shock absorber whose hollow center shaft is fit­ted by having an adjustable orifice that allows vary­ing amounts of shock oil to get bled off from round the piston. This supplies six degrees of damping in each of the three modes. Touring, Sport, and gratification, for a total of 14 steps (not 18, because some overlap). Settings range between very soft to full hard in incremental steps that are governed by vehicle speed. Lest you wonder how the system works, let’s just point out that it’s completed with servomotors (actuators mounted atop each shock and accustomed to turn the shaft that regulates the oil bypass) and a micro­ processor (to sense road condition and speed and to send appropriate information to the ser­vos). This is the first use in hyper-performance terri­tory, though true, other high-volume manufacturers have offered cockpit-adjustable shocks. More about this later if we discuss driving the ZR-1.

Unique for the ZR-1 (and for most of us, its raison d’etre), the LT5 engine is really a lovely ex­ample of double-overhead-cam, four-valve-per- cylinder technology. Developed jointly with Lotus and built by Mercury Marine (the boat motor people), this 5.7-liter aluminum, 32-valve V8 provides the same 4.40-inch bore center spacing (for standardization purposes) since the venerable Chevy small-block. To maintain this distance, the bore has been reduced from 4.00 to 3.90 inches, while the stroke has been increased from 3.48 to 3.66 inches. Aluminum cylinder liners which are lighter than steel are Nikasil-coated, as well as the externally-ribbed block has a cast-alu­minum oil sump and lower crankcase assembly whose integral four- and six-bolt cast-iron main bearing caps secure the forged steel crankshaft. Up top, the LT5’s four camshafts are driven by a roller chain (Gilmerbelts were considered, but discarded because they will have made the engine too wide to get bottom-loaded in to the Corvette chassis on the Bowling Green as­sembly line) and actu­ate hydraulic lifters that eliminate valve lash adjustment. The four-valve combustion chambers feature cen­trally-located spark­ plugs (for reduced flame travel) and are designed to act in con­cert with dished aluminum pistons with an 11.: 1 compression ratio. To ensure all of this very elaborate (and expensive) machinery doesn’t self-destruct for lack of proper lubrica­tion, the engine oiling system holds 12 quarts, 7 greater than the pushrod V8.

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Nothing unusual to date, you say. Any engine worth its salt has all this. Too right. But no other engine in the world offers the LT5’s two-phase induction system that makes the Chevy 32-valver two powerplants in one: a tractable, fuel-efficient, around-town workhorse; and a gut-wrenching, full-on track star that hammers out 380 hp. Using its 16 tuned-length intake runners, the visually distinctive manifold uses a three-valve throttle body with a small primary for responsive low-speed operation as well as two large secondaries for full-power usage. During nor­mal only use, the primary intake ports and fuel injectors are operative. Mash about the gas and let the revs climb above 3500 rpm or to half-throt­tle, and the secondary ports and injectors come into play. Acting under orders from the Elec­tronic Control Module, the secondaries feed the fuel-air mixture to the larger of the two in­take valves whose camshaft lobes have more radical timing for maximum power. In addi­tion to earning the LT5 the most versatile engine worldwide, the two-stage induction system enables the Vette owner to control en­gine operation. A power switch on the console (the so-called valet-parking key) disables the secondary throttles and their injectors, leaving the engine operating at half power-to discour­age unauthorized drivers from using the LT5’s full potential.

The ZR-1’s V8 uses direct-fire ignition: Four coils ignite two spark plugs simultaneous­ly, upon receiving their cue from a crankshaft sensor acting in concert with the ECM. Be­ increase the risk for sensor reads the position of ma­chined notches on the crank, correct ignition timing is ensured. Spark advance and retarda­tion are electronically controlled by the ECM, which gets an additional little information from the knock sensor. Whether idling or at speed, the 32-valver runs no hotter (and gener­ally cooler) in comparison to the L98, thanks to its dis­tinctive cooling system with a 15 percent larger radiator and relocated thermostat (it’s about the inlet side of the engine).

READ: Our 2005 C6 Corvette first drive.

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To help deliver the LT5’s output for the rear wheels. Chevy has given the ZR-1 and the nor­mal Corvette a unique six-speed transmission, which uses CAGS (Computer Aided Gear Se­lection) that automatically short-shifts from first to fourth under light throttle. This beefy, ZF-designed gearbox (code-named ML9) replaces the Doug Nash 4 3 manual overdrive tranny used from 1984 through 1988 and is capable of doing handling a minimum of 425 lb-ft of torque, much more in comparison to the LT5’s respectable 370 lb-ft. When used in combination with the 32-valver, the six-speed drives the back wheels through a 3.54: 1 ring and pinion that gives a slightly lower final drive ratio than the L98’s 3.33: 1.

Naturally, the expected Corvette niceties abound (except for the see-through, hard-coated acrylic roof panel, the ZR-1 is what the trade calls “fully optioned out”). Which means that, in addition to everything mentioned above, leath­er-covered sport seats and that great-sounding Delco/Bose system are standard. Paint schemes are standard Corvette and will include seven hues, but not the yellow seen on the Geneva show car. Interestingly, there is no climate control, simply old air conditioning and heating, be­ cause at this time the fully automatic system won’t clear the right cylinder head.

Considering the car’s limited availability (Chevy wants to build only 4000 annually be­ginning this summer), most early ZR-1s will probably become collector cars, bought at in­flated prices and traded at even higher ones. A pity, because if ever there was an auto that begged to be driven, and driven hard, this can be it. Unlike some exotics that fuss in traffic and fume in hot weather, the LT5 powerplant runs like every good Detroit V8 should: effortlessly, reliably. In city driving (or while following that ubiqui­tous diesel truck along a hilly European two-lane), this muscular V8, which develops 300 lb-ft of torque at 1500 rpm, burbles along hap­pily at practically idle speed. So, there’s no need to do a lot of shifting-or perhaps to let your blood pressure soar because you’re playing follow-the-leader. Don’t worry, be happy, take advantage of the air-con­ditioned stereo-filled environment of the ZR-1, and wait until it’s safe to … PASS!

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Enable the record demonstrate that after easing off the line at about 1500 rpm to avoid wheelspin, the ZR-1 goes from to 60 in 4.9 seconds and gets to the quarter-mile marker in 13.4 seconds. Speed-shifted, Corvette engineer Jim Ingles-style, it’s a few tenths quicker. When it’s time to stop, this 3680-lb sports car comes to a halt in 132 feet from 60 mph and 233 feet from 80 mph. Im­pressive? You bet! Also, better than the very best three exotic cars (Ferrari Testarossa, Lambor­ghini Countach, Porsche Turbo).

In real-world terms, this level of perform­ance means that, according to the amount of room you have to do so, you can either ease into the throttle, activate those giant secondar­ies, and type of swoop past. Or you can down­shift a gear or two (because of the 32-valver’s 7000-rpm redline, there are plenty more revs compared to the normal V8) and blow by that slow­poke con brio! . And don’t fret about ducking back into your proper lane. If it’s wet or maybe if the road surface is gravelly, those giant, vent­ed disc brakes and Bosch ABS will hold you back quickly and safely, even. Or perhaps in time to slow for your DANGEROUS CURVE.

Not a problem. Lateral acceleration (you can just call it handling) has always been the Vette’s forte, but this model sets new stan­dards. Ladies and gentlemen, the new king of the skidpad, the ZR-1. Thanks to its suspen­sion, Selective Ride Control, and those sticky ZR-rated (193-mph) Goodyear Gatorbacks, the ZR-1 toes the (curved) mark at .94g, bet­ter than any production-built automobile, bar none. There’s mild understeer and a feeling of comparative nimbleness brought on by steer­ing that no more feels overboosted and darty (the ratio is slowed from 13.1: 1 to 15.: 1). Nor will be the Super Vette a slouch in the slalom where it slithers with the cones at 65.7 mph. It’s the second-fastest speed we’ve ever recorded, topped only through the Mitsubishi Galant, a car with front drive (which the sla­lom tends to favor) and with an extremely sophisti­cated reactive suspension of the own.

READ: Our first drive in the Jaguar XK180 concept

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The ZR-1 is actually a confidence-builder for any driver who suddenly discovers that a certain constant radius turn, isn’t. At times this way it keeps all four feet (or tires) planted firmly on the pavement and maintains its composure-having a deft flick of the wheel or tap of the throt­tle, if required.

Much of the credit with this improvement in vehicle attitude and ride goes to the Corvette’s Selective Ride Control package. Unlike the suspensions of yore (standard equipment on the 1989 normal Corvette) that provided either soft ride or good handling, FX3-equipped L98 and ZR-1 Vettes offer both-in varying degrees depending on switch setting.

On bumpy roads including some of the French goat paths encountered in the ZR-1’s Eu­ropean press introduction, the Touring mode is most effective. This soft setting not simply keeps one’s fillings intact, but also definitely makes the suspension more compliant (better able to absorb much of the road’s roughness) and enables the wheels to stay in connection with the pavement.

On smooth, fast roads or with a test track such as Goodyear’s Mireval proving grounds near Narbonne, France, the Sport or Performance modes are best. Here, the flat surface ensures that the ZR-1’s Gatorbacks are in constant experience of the pavement, so the function of shock-absorber damping becomes certainly one of chassis tuning. Suffice to say that the middle (Sport) setting is probably best (even Corvette Challenge competitors use it), as the full hard setting helps make the suspension very respon­sive to steering input, and (ahem) quite stiff.

From the outset, the Corvette group sought to make the ZR-1 one of several fastest produc­tion-built cars worldwide. If those Countach curmudgeons and testy Testarossers quickly discuss that its 172-mph top speed falls a few digits short of the Lambo’s flat-out 179 mph and the Ferrari’s 185-mph figure, and so it is, even. Perhaps they should keep in mind the ZR-1 was tested in California’s high desert with minimal approach room, while the exotics were tested in Europe at Volkswagen’s Ehra-Lessien test track, where we think, given miles to chill, the LT5 could manage high 170s. Consider additionally that the Lamborghini and Ferrari are specially-built automobiles costing almost three times as much as the ZR-1, which is built on the same assembly line as the normal Vette. And costs $50,000, a bargain considering the level of performance and comfort it delivers.

But is it, as Chevy hopes, a world-class car? (The envelope, please! )

Yes. The Corvette ZR-1 acquits itself well amidst some extremely fast company. Yet it does so with a level of comfort and class be­yond what most exotics (but not specialty cars including the Porsche 959) currently deliver. Throw in availability and serviceability (the GM-CAMS computer diagnostic system, man­datory service equipment for all ZR-1 dealers), and you have a car which offers the best of the previous and the new world.