What Does 'Z51' Mean For Performance On A Chevrolet Corvette?

In the spirit of the rare, comprehensive trims of yesteryear, the C8 Corvette Stingray's Z51 Performance Package boasts a number of motorsport-inspired add-ons focusing primarily on improving handling and responsiveness. The list of accessories the Z51 adds is fairly inclusive, including:

• Michelin Pilot Sport 4S summer tires
• Firmer suspension, including spring rates and passive dampers
• Low-profile splitter and multi-plane rear wing, the easiest way to spot a Z51-equipped Corvette
• An extra radiator, fitted to the air intake, along with a transmission cooler
• Larger brake rotors with bodywork cooling ducts
• Electronically-controlled limited-slip differential, shorter final-drive ratio, and Performance Traction Management (PTM)
• High-performance exhaust, upping power and torque to 495 horsepower and 470 pound-feet, respectively

Chevrolet claims on its homepage that the Z51 Performance Package is "required for track use." In fact, every one of their options emphasizes the track before anything else. Would it actually make any difference, though? 

There's a common phrase in motorsports: "slow is fast, fast is smooth." That means repeatability through consistency makes all the difference in improving lap times when racing. To that end, the Z51 package is geared towards being able to accurately predict what a car will do and keeping rhythm for extended periods of time. In theory, you should see a marked difference, right? Well, none of these upgrades will substantially hinder performance for everyday drivers at normal traffic speeds; the only difference you'll likely notice is a somewhat stiffer ride, thanks to the higher spring and damper rates. The real changes lie in how the car handles on track. 

At a glance, the upgrades themselves appear relatively minor for the most part. Take the 13.6-inch front brakes (one inch larger) and 13.8-inch rears (just a half-inch larger), for example. Such an upgrade typically isn't meant to directly impact braking performance in a measurable way, but to help dissipate heat and prevent brake fade under heavy, consistent loads, assisted by the added brake ducts. 

Then you have other equipment like the transmission cooler, which will only aid you after driving hard for extended periods. It may not be outright seconds faster on track, but that's not the point. The point is to give the driver the confidence to do consistent lap times and the longevity to keep a good rhythm. It lets you stay on track longer and put in more lap times.

Another factor is that "minor upgrades" do add up over the course of a lap. At my local track, NJMP, Turn 12 of the Thunderbolt layout is a fast right-hander taken at triple-digit numbers. It requires a lift off the throttle in high-powered cars, most certainly a standard C8. The Z51 would perform somewhat better here, with the aero and LSD affording it more consistency. It'll also have more confidence heading into Turn 1's heavy braking section, and the LSD will help keep wheelspin under control through the low-speed final sector.

Is it necessary, though? Well, these are largely differences only affecting drivers willing to really push their machines. The Z51 package is designed to slightly extend the Corvette's natural limits, not drastically change its behavior. So, if you enjoy the Corvette but wish it had more staying power on a circuit, then the Z51 is for you.