Yahoo Autos 1,064 Horsepower, 215 MPH: The 2025 Corvette ZR1 Conquers All
"The ZR1's always been king of the hill," says Tadge Juechter. "This car, I think it embraces that pretty well." That’s a bit of an understatement from the recently retired Corvette executive chief engineer, as the 2025 Corvette ZR1 ties a 1,064-horsepower bow on Juechter's legendary career. There are more astonishing numbers to go with the four-figure horsepower output. 838 pound-feet of torque. A sub-10-second quarter-mile at 150 miles per hour. A top speed "comfortably over 215 mph." Even in a world where extreme horsepower has been normalized, the ZR1 is a high water mark for internal combustion performance.
Especially when you look back at the Bugatti Veyron, which required 16 cylinders and four turbochargers to make 987 hp (1001 hp on the metric scale) at a price of around $1,250,000. 20 years of progress means the ZR1 gets it done with half the cylinders and half the turbos, and in the Corvette tradition, at a steep discount compared to the cars it seeks to outperform. Chevy won't announce pricing until closer to the mid-2025 production date, but expect it to be more than the $114,395 Z06 — and significantly less than the Ferrari SF90 Stradale and Porsche 911 GT2 RS that the Corvette team benchmarked.
"We never do just an engine program," Juechter says. "It's always a fully developed car, and this car is no exception."
That said, the LT7 small block is the obvious focal point of the car, and the other changes are the reverberations from the V-8's power. Perhaps surprisingly, though, the ZR1 was in the plan for the C8 generation from the outset, including space to fit the turbos and preserve room for the folding convertible top. (Yes, the ZR1 will be available as both a convertible and a targa-roof coupe.)
So, why turbocharging? "If you bolt on a supercharger and couple that to a lightweight crank train, you don't have a lightweight crank train anymore and you lose a lot of that character," says Dustin Gardner, assistant chief engineer for small block engines. "And you start playing in the 1,000-horsepower realm, you're going to have to run a 200-horsepower supercharger to make that kind of power. The inherent efficiencies of turbocharging become a big deal here."
The LT7 V-8 shares the same block casting and 5.5-liter displacement as the LT6 found in the Z06. As with the overall project, this was in the plan from the start – both engines were developed in parallel. As Juechter puts it, "Everything that needed to be bespoke for the turbo engine was bespoke for the turbo engine. We weren't constrained by what had been done on the naturally aspirated engine." And while the block is common, the LT7 gets additional machining to support aspects related to the turbo setup.
So what's different? The LT7 uses the same rev-friendly flat-plane crankshaft as the LT6, but with slightly different machining to clear the other beefed-up parts. Like the piston rods, which are bigger and shorter. The latter preserves the same 80 mm stroke as the LT6 but brings the piston further down in the combustion chamber. That, along with a shorter piston, drops the compression ratio from 12.5:1 down to a more boost-friendly 9.8:1. Further up, the LT7 gets a unique larger casting for the pin bores and its own piston. The heads on the LT7 are also unique, including different intake ports that make room for the combination port and direct injection fueling system, where all 16 injectors are needed to make the peak power.
The LT7 has the same dry-sump oil system as the LT6, but enhanced to keep the turbos lubricated. "Obviously with low turbos, what you're going to struggle with is oil control. So we have a dedicated scavenge pump that is 100% dedicated and plumbed directly to both turbos," says Gardner.
On the intake side, the LT7 manifold is unique in that it has a lower volume than the LT6 but also each cylinder bank is isolated. "The engine and boosting system works truly like two four cylinders. We control them independently of each other," says Gardner.
And then there are the BorgWarner turbochargers, which run about 20 psi of boost in normal conditions. They use an electronic wastegate that helps reduce turbo lag, thanks to software calibration that takes overall driving conditions into account. Lift off the throttle when you're driving hard and the wastegate closes to maintain boost pressure; that way, as Gardner explains, "when you come out of that braking zone, that corner, and you roll back into it, the turbo's at speed, you have boost ready to go. In this situation, there's virtually no turbo lag because we maintain turbo speed during those off-throttle excursions."
This all adds up to a peak power of 1,064 hp at 7,000 rpm and 828 lb-ft of torque at 6,000 rpm. Redline, at 8,000 rpm, is 600 lower than the LT6, but the V-8 is "still a real spinner motor," as Juechter puts it. But why stop at 1,064? Why not 1,065? "We didn't set a target horsepower ahead of time. We said we want the most technology will give us," says Juechter. "But in the tradition of Corvette, it's validated the same way as all our other stuff. Validated for 150,000 miles on the street, we do our 24-hour continuous operation on the track, all the standard robustness tests that we do."
A less hot answer: 1,064 hp is plenty. The torque curve is nearly flat, and above 800 lb-ft from 3,000 to 7,000 rpm. The 375-hp of the LT5 in the 1990 ZR1? The LT7 makes that at 2,800 rpm. At 4,100 rpm, the LT5 has the 2009 LS9 engine beat. As for the last ZR1, that brought back the LT5 name, well, the LT7 makes the same 755 hp at a mere 4,750 rpm.
That power and torque requires strong gears in the eight-speed dual-clutch gearbox. That means wider gears and stronger shafts. Here again, though, it was laid into the C8 design from the start, according to Juechter. "This had to be planned way back from the beginning. We knew we had this torque monster coming out."
And so, the ZR1 has the same transmission housing as every other Corvette, although this version has improved lubrication to deal with the car's higher capabilities on the track. The integrated approach doesn't scream "special" in the way that previous ZR1s did; there are no major structural changes, the available seat options are the same at the Z06, and so on. And that's a good thing, in the same way that Porsche's 911 variants are integrated into the overall model plan. It means there's less re-engineering, and the end result is more cohesive.
Naturally, the engine upgrade necessitates several other changes, most of which are focused on cooling. Making this much power also results in a lot of heat that needs to be managed. The front cargo area is gone; in its place are two big heat exchangers between the frame rails — one is for engine coolant, the other for the turbo intercoolers. There are also more radiators on the front corners. The central radiators spill out through a large hood extractor. This is helped by a Gurney flap on the leading edge, which provides front downforce as well as low pressure behind it to further extract hot air after it’s passed through the exchangers.
On the driver's side, aft of the door are two prominent intakes: one for engine air and one for brake cooling. And then there's the big wing, the most prominent feature of the ZTK performance package. It's cantilevered out over the back of the bodywork, so that the rear trunk area is still accessible.
“It's a bit of a lift, but that's the price you pay to get that kind of performance,” says Juechter.
And while less performance-related, there's one more prominent change on the ZR1: the return of the split window. Despite appearing for just a single model year in 1963 (or perhaps because of it), the bifurcated rear glass remains an iconic piece of Corvette design history. In the ZR1, concerns about rear visibility are mitigated, to a degree, by a rearview mirror that can broadcast the feed of a camera mounted in that center strip.
All of the ZR1's speed is complemented by upgraded carbon ceramic brakes, which use longer fibers and have more ceramic material on the rotor surface, resulting in improved heat transfer. Surrounding those brakes are new optional carbon fiber wheels from Carbon Revolution. The 10-spoke design looks visually lighter than the five-spoke pattern first used on the Z06; actual weight savings is around 40 pounds total compared to the aluminum rims, which Chevrolet says is worth about a second and a half of lap time on the Milford Road Course circuit at GM's proving grounds.
The tires are same size as the Z06 – 275/30ZR20 in front, 345/25ZR21 in the rear – but are upgraded to cope with the ZR1's higher performance. "We actually built a mule way early on with as much horsepower as we can get to try to do some of the tire tuning," says Juechter, "but when we got to this actual car... it's higher performance than the mule that we built. So we had to tweak some of the tire construction."
And while the ZR1 will post the fastest lap times of any Corvette – how could it not, really – it's still meant to be an all-around GT car. The base chassis for the ZR1 uses lower spring rates than the Z06. "We're spanning actually a bigger market bandwidth on ZR1 than we are on Z06," says Juechter. Order the ZTK performance package, which includes Michelin Pilot Sport Cup 2 R tires (in place of the standard Pilot Sport 4S) and all the aero bits that add up to 1,200 pounds of downforce. That’s available in both coupe and convertible form, and the carbon fiber wheels are a standalone option.
At the outset of the program, the ZR1’s performance even surprised its creators. As Juechter tells it, "Early, early prototype versions of this car were quicker than the production [C7] ZR1. If you know anything about vehicle development it's usually crawl, walk, run, and you don't get to big speed until late in the program. This is the first time I can remember where out-of-the-box the prototypes are faster than the production version of the car before it."
GM's sneak peak of the car included a ride in the passenger seat for a straight-line sprint with development driver Chris Barber. Rolling into the throttle from about 20 mph, the ZR1 pushes your entire body back into the seat. That's expected, even with the limited traction of rear-wheel-drive. What's unexpected is that the physical sensation continues well past the initial instant and keeps going up to about 90 mph. The way the car attains speed, the digital instrument cluster jumping in 10-mph increments, is almost disconcerting. You wouldn't know from watching Barber's hands, which are calm and stable as he makes minimal adjustments. As fast at the ZR1 is, the run's peak of 206 mph is oddly uneventful.
It will still be a while before anyone outside of GM gets a chance to see if the ZR1 driving experience lives up to the performance numbers. The full reveal seen here isn’t just to build excitement, but also allow for the final stages of testing. "It's so edge-of-the-envelope on aero balance, ultimate performance, heat exchangers doing the cooling of the vehicle, all the different aspects of cooling. We can't really do that work with a bunch of cladding all over the car. We always learn things when we take that off."
From what we've seen so far, and considering how the C8 Zo6 has blown away all expectations of what a Corvette can achieve, it's hard to imagine the ZR1 will be anything but mind-blowing.
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