Yes, the Chevrolet Corvette ZR1 has 755 horsepower. But that’s not the only thing that’s special about the car, says Corvette chief engineer Tadge Juechter.
“Of course we want more power, our customers always want more power, but just more power is not a good car,” he says. “We pride ourselves on doing well-balanced cars that do a lot of things well.”
After all, the ZR1 has a huge list of handling, braking, and aerodynamic upgrades to make it a road-course champ, too.
“People will probably think of this as a Z06 with 105 more horsepower,” Juechter says, “But they should think of it more as a Grand Sport with 300 more horsepower.”
Still, that engine attracts a lot of attention. Though in the ZR1 it’s called LT5, the 6.2-liter V8 still shares “quite a few” parts with the Z06’s mill, including the block. But its heads, crankshaft, and so on are all different to produce more power. it’s also much taller than the Z06’s engine – so much that the top of the engine now protrudes out through the hood.
“The taller the engine is, the more power you can get out of it,” Juechter says. “The supercharger can be bigger, you can put bigger intercooler bricks underneath it, you have a straighter shot between the supercharger and the inlet ports on the engine.”
Although the peak horsepower and torque numbers are obviously higher than in a Z06 (by 105 hp and 65 lb-ft), Juechter stresses that the LT5 engine outperforms the Z06’s LT4 across its power band.
“You can feel it in every gear at every speed,” he says. “You don’t have to wind it out, it’s ready to go … It’s just shockingly quick, even from highway speed.”
Unlike other Corvette engines, the ZR1’s doesn’t have cylinder deactivation because the complicated feature added too much weight to the valvetrain for its more aggressive cam profile.
Chevrolet is confident in quoting the ZR1’s top speed of 212 miles per hour because the company verified it in real life. That figure – more exactly, 212.48 mph – was the average of two flying-mile runs at Papenberg test track: “It’s a track in Germany with very, very long straightaways and high-banked turns.”
That speed, by the way, is achieved only with the car’s standard wing setup; opting for the High Wing option saps about 10 mph of maximum speed, Juechter says.
The ZR1 does have an electronic speed limiter, set at 215 mph in deference to the tires’ speed rating.
“We didn’t actually expect to get there, but we were surprised when we hit the speed limiter,” Juechter says. “We talked about raising it [the limiter], but the tires were validated to 215.”
Customers Wanted The Automatic And Convertible
That’s really the simple reason for the ZR1 offering its first-ever automatic transmission and the first convertible since 1970. The C7-generation Z06 had already introduced an automatic gearbox, and it is so popular that 70-80 percent of Z06s have the auto. Juechter says that for some customers with family members who can’t or won’t drive a manual transmission, that could be a deal breaker.
“If you don’t offer the automatic as a choice, sometimes they can’t buy the car,” he says. “I talked to a lot of people who didn’t buy a C6 Z06, they bought a Grand Sport because they could get an automatic transmission.”
As to the transmission’s toughness, Juechter says the General Motors-built eight-speed is plenty durable for use in the high-performance ZR1 – “As long as you keep it cool, it’s fine.”
The ZR1 convertible, meanwhile, does not need any extra chassis bracing compared to the coupe, because the regular coupe already has a removable roof panel.
“We baked all that stiffness and strength into the basic architecture,” Juechter says. “So there’s really no reason not to offer the convertible.”
In fact, the only structural changes for the droptop ZR1 involve moving the seatbelt mounting points; the only weight gain comes from installing the power-folding soft top.
Cooling Is Key
There are four extra heat exchangers used for the ZR1 compared to a Z06, and the front fascia is dominated by radiators and intercoolers. Chevy wanted to make sure the car could withstand hard track use without overheating, so it put it to the test with a more rigorous test. The validation test for the car’s cooling system involved a professional driver pushing the car on a track until it used up an entire tank of fuel. And for the ZR1, the ambient temperature during that test had to be 100 degrees Fahrenheit, whereas Chevy had previously used 86 degrees as its testing standard.
The angle of the optional High Wing is adjustable by five degrees, letting owners choose how much drag versus downforce they want for road or track driving. At its maximum angle of attack, Chevy recommends owners also lower the front suspension by half an inch. Adjustment screws at the ends of the front composite springs allow owners to do that on their own, Juechter promises, and lowering the nose helps provide more front downforce to compensate for the increased rear wing performance.
It’ll Still Get Loud
A new spring-loaded valve within the active exhaust system opens in a more “linear” way to increase the car’s volume as engine load increases. “It gradually opens up as more flow comes through, and it gives it a more linear character,” Juechter says. “This has a much smoother transition from quiet to loud [compared to the Z06].” Chevrolet has applied for a patent on this system.
Not Only For The Track
Although Juechter says about five percent of Corvette owners take their cars to the track, even the ZR1 was intended to be just as everyday-usable as any other model.
“If we were trying to do a pure track machine, it would be much easier … But even at this level of performance, we still worry about making the car very usable, very accessible,” he says. “We act like people are going to use it like a normal Corvette.”
For instance, the suspension spring rates are “very similar to a Z06,” so Juechter promises that, “On-road, the ride frequency is still pretty compliant.” (The High Wing model has stiffer springs to account for the increased downforce.)
Another example: because there’s so much force pushing down on the rear wing, it needs to be solidly mounted to the car’s frame. Engineers could have simply put brace through the trunk space, but instead fitted aluminum castings behind the fascia that attach the wing to the car’s bumper beam.
“We wanted to keep all the luggage room that people had gotten used to,” Juechter says.
More power everywhere “Don’t have to wind it out”
Breaking Lap Times
“The Z06 set a lot of track records when people tested it. This car will break those.”
Juechter is pretty confident about that, promising that thanks to the ZR1’s extra downforce, power, and other upgrades, “There’s no track where the Z06 will be faster.”
“We don’t have a Nürburgring time but we’ve tested it [the ZR1] at other tracks … and eventually we’ll publish those," he says. In other words, stay tuned.