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.
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.
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.
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.
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.
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.
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.