"I'm certain that with more track time, braking much later into the turns, I could shavesubstantial time off my laps. The ZR1 definitely moves around more as it works the track. There's more side-to-side and front-to-rear motion. The Z06 tracks much more flatly. Both cars were run in the Competitive Driving setting, with the ZR1's magnetic suspension set to Sport.
"In normal driving, the ZR1 can demonstrate truly bipolar behavior. Driving her home from Bowling Green, she was quite docile: quiet, comfortable, and easy to drive, with a feather-light clutch and low-effort shifter. But when you want to switch to Mr. Hyde, the flaps open on the pipes, the supercharger winds up, and the suspension anticipates your needs.
"The Z06 is one car--a track car--and it's quite good in that role. But the ZR1 is truly more car. Honestly, I feel I could part with both my '06 Z06 and my 700hp '01 Mallett Z and have all my motoring needs fulfilled with the ZR1. But variety is the spice of life, right?"
Chassis Dyno
Not long after our Sebring visit,Helmintoller'sZ laid down 558.22 hp and 524.86 lb-ft of torque on the chassis dyno at Seffner, Florida-based Corvette tuner AntiVenom. A pair of back-up runs delivered power readings within 7 horses; torque, meanwhile, climbed to a high reading of 541.19 on the third pull. Using a 15 percent correction factor yielded best-of-day flywheel readings of 656.73 and 636.69, respectively--easily eclipsing the factory numbers of 638/604.
Could our results have been anomalous? Not according to one GM source, who stated that the LS9's official horsepower rating is based not on an average of all engines tested for certification, but rather on the lowest-performing engine in the test sample. In an age when overpromising and under-delivering has become the corporate norm, it's refreshing to see that Chevy has taken the opposite tack.
Assuming 638 (or more) horses aren't enough to set your blood aboil, you'll be pleased to learn that the ZR1 appears to respond well to traditional power-enhancing tricks. One week after our initial dyno session, Helmintoller returned the car to AntiVenom to have its ECM programming optimized. By slightly leaning out the LS9's air/fuel mixture, AV's Greg Lovell managed to bump the output totals to 570 hp and 553 lb-ft. Throw in a set of headers and a smaller blower pulley, and 650 rwhp seems like a real possibility.
Dragstrip
Our original intention was to perform our acceleration testing during a closed session at nearby Bradenton Motorsports Park. This would allow Helmintoller to cool the engine with ice prior to each run and drive straight to the starting line without waiting around in the staging lanes. But when no such sessions materialized during our limited time frame, we were forced to enter the car in one of BMP's regular weeknight test-and-tune sessions. It wasn't an ideal arrangement, but it would have to do.
After making a series of passes to acclimate himself to the ZR1's beastly torque output, Helmintoller managed to record a best e.t. of 11.44 seconds. That falls a bit short of GM's claimed time of 11.3 seconds, but it's hardly disappointing for a first effort. It bears mention that even on the glutinous stock Michelin Pilots, careful throttle application was required to keep the Z from furiously spinning its wheels clear through the top of Second gear.
An accompanying trap speed of only 123.03 mph initially had us scratching our heads (GM says the ZR1 is good for 131), but upon closer examination, it appears that a number of factors may be to blame. First, the weather was typical early-fall Florida, with temps hovering in the high-80s and humidity climbing a few digits higher. Perhaps more important, the constant clutch slipping (required to achieve something approximating launch traction) and repeated hot-lapping employed throughout the afternoon likely conspired to keep the blown LS9 from revealing its true potential. With a few more break-in miles, some cooler air, and a pair of drag radials, the new Corvette flagship is almost certain to crack the 10s at 130-plus. Stay tuned.