1990 Chevrolet Corvette ZR1 - Long Live The King!

Richard Newton Mar 17, 2010 0 Comment(s)
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It takes a lot to be a legend. And when the subject turns to legendary Corvettes, we're really talking about "legends within the legend." For many years America's Only Sports Car, Corvette still reigns as America's Favorite Sports Car; the marque is a cultural icon with a storied past, the car little boys and girls (and more than a few adults) have dreamed of owning for years. To gain exalted status within the Corvette legend is no small feat. There are the fuelies of '57 and '63, the split-window, the big-block mid-years, to name a few; and, of course, the '90-95 ZR-1.

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The new, sleek, and aerodynamic C4 Corvette had barely hit the pavement before talk of the need for a new, powerful, world-beating engine started deep within General Motors. The new Vette was an immediate success, but the Cross-Fire powerplant did leave something to be desired. The 1985 upgrade to the 230hp L98 brought some degree of respectability, but the car's success in Showroom Stock racing made it obvious that the new platform could handle much more power. Corvette Chief Engineer Dave McLellan definitely wanted more power.

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GM was also concerned with maintaining its leadership in the American sports car market. The Japanese had taken over the economy car market, and had their sights set higher. GM like such as Vice President Lloyd Reuss saw this as a serious threat, and was among those at GM who were determined to keep Corvette on top.

Anyone's who interested already knows that the development of Chevrolet's first new small-block V-8 since the '50s ended up in the capable hands of Lotus Engineering (See the accompanying article by Richard F. Newton, "ZR-1: The Ultimate C4," page 46). This process in itself is the type of story that lends itself to legend. Although Lotus had been discussing possibilities with Chevrolet starting in mid-1984 (one of these being the adaptation of four-valve, double-overhead cam heads to the small-block Chevy), the agreement to build an entirely new engine, one that would make 400hp and still be completely civilized, was not struck until May 1985, and Lotus did not get started until August of that year. The first engine had to run in May of '86-it had to make it into a car by August. It would be understatement, to say the least, that this was an incredibly short amount of time in which to design and build an engine from scratch. But those involved got it done.

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The development process was another story. Lotus began the arduous detective work inherent in ferreting out the flaws in a new engine-problems such as oil control and breaking cam chains. While work progressed across the pond, it shifted into high gear here in the States. The MerCruiser Division of Mercury Marine was chosen to build the LT5, and had the unenviable task of setting up an assembly line before the final specs of the engine were even finalized. Changes came on a daily, if not hourly basis, but the commitment was there, and it was strong. Chevrolet had preproduction LT5s to show off in early 1988, and introduced the ZR-1 to the press at the now-defunct Riverside Raceway in the middle of that year.

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At this point, Chevrolet decided to wait and introduce the "King of the Hill," as it had come to be known, as a '90 model with all the changes planned for that year. But the buzz was there, and this was the car that American enthusiasts were talking about and dying to get their hands on.

Most of us in the Corvette hobby know what happened at this point: The 1990 Chevrolet Corvette ZR1 was introduced to the press in France, where the members of the third estate were quickly convinced of the new super-Vette's capabilities, and then it was time. The public could finally get a shot at the Corvette of Corvettes.

"Don't believe the hype" became a popular saying in the '90s. When it came to the ZR-1, however, this one never quite caught on. The new Vette delivered what it promised-almost. It's 385 hp did come up short of the 400 mark, at least until 1993's power upgrade (see "40 the Fast Way," page 34). But if the rate those first cars were snapped up-even with the approximately $30,000 the ZR-1 option cost and some hefty dealer mark-ups-was any indication, it was close enough.

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Here was a car that did it all. It was a docile, cool-running street car with great gas milege one moment, but turn that "Power" key, kicking in the secondary fuel injectors and intake runners, and you were ready to deal with anything Germany or Italy had to offer. The ZR-1 was, and is, everything that Corvette had been up to that point. At once brutish and refined, it seamlessly melded Dr. Jekyll and Mr.Hyde into one damn sexy package that could handle anything you cared to throw at it.

Ironically, the success of the ZR-1 is part of what killed it. The new car's rear fascia became standard on the base model starting in 1991 (albeit in a narrower version), essentially making the two indistinguishable. The LT-1 development team was spurred on to come close in performance, and they did so, for a lot less money. Production declined and price went up, and less people became willing to pay for an engine option that cost almost as much as a whole base Corvette. Citing prohibitive EPA certification costs for 1996, Chevrolet stopped LT5 production in 1993, and sold the last ZR-1s in 1995. The King was dead.

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Well, not really dead. This is a happy story in some ways. The ultimate Vette lives on in the hands of those who are lucky enough to own the only car that can carry the title "King of the Hill." A twist of that power key followed by a stomp on the loud pedal is all it takes to remind a Corvette enthusiast that, in many ways, this is the Corvette.

But where are we now? Well, the developers of the still-new LS1 are another group that was inspired by the success of the LT5. Of course, there are rumors that we're going to see a sizeable power increase for the C5 next year. And we know the chassis can handle more power, as well as handling upgrades. Sound familiar? Let's hope lightning strikes twice. Until then...Long Live the King!

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(For those wishing to read more about the King of the Hill, VETTE recommends The Heart of the Beast by Anthony Young, ISBN 0-911968-99-7, published by Automobile Quarterly, Inc.)

10 Ways To Identify A ZR-1
1. Logo on right rear bumper.
2. Raised "Corvette" lettering on rear fascia.
3. Three-inch wider rear fascia with spacer panels on either side of license plate.
4. Side fender logos on '92 and later models.
5. Menacing, throaty exhaust note.
6. Eleven-inch rims with 315/35-17 tires in the rear.
7. Four square exhaust outlets on '90-91s.
8. Hatchback-mounted center high-mounted stop lamp.
9. Specially laminated "solar" glass with a "hole" in the windshield for radardetectors.
10. That rapidly disappearing dot on the horizon as you struggle to keep up.

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ZR-1: The Ultimate C4
The ZR-1 was the real C4 Corvette. Everything that came before the ZR-1 was just practice for the real thing. The ZR-1 was the Corvette that Dave McLellan thought about when he first envisioned a Corvette that would replace the old Stingray. He wasn't really sure how this dream Corvette would turn out, but he knew that it had to be something special.

Every era of Corvette has a special car. When it comes to the C4, the ZR-1 is that unique and historic contribution to Corvette history. People too often think of the ZR-1 simply in terms of the LT5 motor. It was that, plus it was a lot more. Remember, the LT5 motor just wasn't dropped into a standard C4 Corvette. We need to realize that the entire C4 program was wrapped around the LT5 motor. The L98 and LT1 engines were simply a way of being able to sell the Corvette in some sort of volume. The C4 Corvette chassis was for really big power.

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When people ask the question about why the ZR-1 didn't look different, they miss the point. The real question we should be asking is why the '84 to '96 Corvette was actually over-built. The base Corvette was much stronger and could handle much more power than the standard Corvette engine could ever produce.. The C4 Corvette was far stronger than necessary, considering what the L98 Tuned Port Injection engine produced in the way of power. This was all a part of Dave McLellan's master plan-a plan that he was formulating during the development of the '84 Corvette-a plan for the ultimate Corvette.

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The ZR-1 project actually began as a turbocharged V-6. Russ Gee, then the director of GM Powertrain, had to listen to almost nightly campaign speeches for a more powerful Corvette. There was a lot of concern that Toyota and Nissan were developing cars that would humiliate the Corvette. This V-6 tubo program was seen as a preemptive strike on the island of Japan. Chevrolet could not wait-they had to be out front with the Corvette.

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While these V-6 turbo engines produced tremendous amounts of power, there was the very simple problem that most people thought of the Corvette as a V-8-type of car. No matter how much power the V-6 produced, it would still be a six-cylinder engine with a lot of add-ons. The idea was that the Corvette customer would want more.

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This is where the development process got a little more complicated. After considerable anguish the Corvette group decided that the Corvette customer really wanted a V-8 engine. The Corvette was a car that by definition needed V-8 power. Just as a Viper will always have 10 cylinders, the Corvette will always have eight cylinders.

At this point the basic engineering problem was to produce a V-8 engine that had tremendous power. There are really only three ways to do this. The first, and perhaps the most elegant engineering solution, was turbocharging. This was the basic reason for the turbocharging programs.

The early quest for Corvette power went down the turbocharging road. GM contracted with Reeves Callaway to develop a turbocharged V-8. For a few years this was seen as the solution to the problem of more power. The twin turbos of the Callaway developed the power that McLellan wanted. When we look back at the performance figures of the Callaway Corvettes and the early ZR-1s there's very little difference in performance.

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A second way to produce massive power is with cubic inches. This was the option DaimlerChrysler took with the Viper. The Corvette group looked at this option with a 12-cylinder Corvette, which is currently on display at the National Corvette Museum. The only problem was that GM had, and still has, a policy that no GM customer will ever pay a gas guzzler tax. This meant the cubic inch solution was a dead end.

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The third way to produce power is to go with multiple valves and overhead cams. This is a fairly expensive solution but looks very high-tech. Corvette ended up going this way after having thoroughly examined the turbocharging route with Reeves Callaway. Just having power wasn't enough to guarantee sales. The engine had to look like it produced power as well. Only overhead camshafts and multiple valves would meet this need.

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The new fashion in engines was to use dual overhead cams and four-valve cylinder heads. This was perceived to be much higher-tech than the simple addition of two turbochargers. GM wanted the world to know that it, like the Japanese, could produce high-performance engines using the latest technological solutions. GM felt that it had to demonstrate that they had the ability to design and build DOHC engines.

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Once they decided on the DOHC solution the fate of the turbocharged engine for the Corvette was sealed. The decision had been made that any new mega motor had to be percieved as a high-tech item. The only question was how to get a DOHC multi-valve engine built.

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Chevrolet had already done work with Cosworth in developing the Cosworth Vega, and felt they had some skill in this area. The problem was that Cosworth simply didn't have the manpower to carry out the task.

Russ Gee, of General Motors, knew that he had to find some help. In early November 1984, Russ Gee went to England to see his old friend Tony Rudd at Lotus Engineering. The thought was that Lotus could develop a set of cylinder heads for the venerable 350 ci engine.

I'm always delighted by the story a friend of mine at Lotus tells about how GM "came to us looking to purchase a set of cylinder heads and we ended up selling them a whole bloody motor." At the same time Gee was talking to Lotus, they were also investigating the abilities of Illmor, Porche, and Cosworth. Eventually, the choice was made to go with Lotus. By early 1985, this new Lotus engine was on the road to development. At this point the goal was to still simply build a set of cylinder heads.

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Then, in the backyard of Russ Gee's suburban Detroit home, Tony Rudd explained over barbecued chicken how the existing 350ci block would never work. Rudd argued that if they constructed a totally new cylinder block to go with the new cylinder heads, Lotus could guarantee 400 hp. A simple cylinder head project had suddenly taken on a whole new meaning. This was going to be the big one. This was an L88 for the '80s.

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The good news was that Lloyd Reuss, then a GM vice president, was on Dave McLellan's side. It took someone with this sort of clout to advance the program to the financial people. This was a program with low volume, high expenses, and tremendous risk. This was not exactly the type of program that GM management loved.

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Once the LT5 project was approved, everyone knew they had to move as quickly as possible, since upper management could cut the funding at any time: "The General giveth and the General taketh away." This thing had to move quickly.

The first LT5 engine was fired up at Lotus on May 1, 1986. The first production LT5 engines came off the assembly line in Stillwater Oklahoma on July 13, 1989. Dave McLellan finally had his real Corvette.

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