Barring a full-on financial meltdown (an outcome that seems far from implausible at press time), GM will build between 1,500 and 2,000 ZR1 Corvettes for the '09 model year. While those numbers aren't sufficiently scanty to qualify the car as a genuine exotic in the vein of an Enzo or a Veyron, they nevertheless represent but a tiny fraction of the Vette's typical yearly production total. Factor in the Z's stupefying performance and six-figure price tag, and it's easy to see why access to examples for use in instrumented testing is severely limited.
Fortunately for us, we know Kevin Helmintoller. Longtime readers may remember Helmintoller as the unrepentant Corvette kook whose exploits behind the wheel of various high-performance Vettes have been documented here in the past. In September, the Tampa-area native lit out for the Corvette Assembly Plant in Bowling Green, Kentucky, to take delivery of his own ZR1, a very-early-production example done up in cop-bait Victory Red. Shortly after arriving back in Florida, he contacted us to ask if we were interested in setting up a battery of performance tests on the new car. We were.
The plan was simple in theory, if not in execution. Helmintoller would wring out the Z in three separate test environments--dyno, dragstrip, and road course--and we would document the results. Orchestrating the project required no small amount of creative scheduling, but when the tire smoke had dissipated, it was clear that Chevy's new King of the Hill was worthy of its regal appellation.
Road Course
Straight-line acceleration testing is instructive, to be sure, but the ZR1's real metier is road-course dicing, and any proper evaluation of the car would be incomplete without the inclusion of a proper open-track session. To that end, Helmintoller enrolled himself and two of his Corvettes--the ZR1 and a mostly stock '06 Z06--in a high-performance driving event hosted by Chin Motorsports and held at Sebring International Raceway. The event promised the opportunity to unleash both cars on one of North America's oldest and best-known motorsports venues, and to draw some informed comparisons between the two.
We'll Helmintoller take it from here.
"Racing in any of the club events at Sebring involves multiple cars on the track at the same time, so any lap times have to be considered with that in mind. Passing occurs only when the driver being overtaken has approved the pass. All of the participants were quite courteous save for one Porsche Carrera driver, who forced me to paint his rear bumper for two laps before finally allowing me by. We also had a rain shower at lunchtimethat wet the track pretty well, and then intermittent showers though the afternoon. That also had an effect on lap times.
"After first being approved for my solo qualification in the ZR1, I switched to the Z06. Perhaps because of my two prior sessions at Sebring in that car, I felt quite comfortable in it. I ran at 10/10ths and was able to turn consistent 2:34 lap timesin traffic. The Z06 is quite tossable, and when it breaks away, it is quite easy to recover. Keep in mind this car has minor mods and makes 490 rwhp and 450 rwtq. It's also equipped with Nitto 285s in the front and 345s in the rear, along with Hawk ceramic brake pads. I felt comfortable pushing that car for all it was worth (and in fact pushed it past that point at least twice).
"With the ZR1, I was definitely more conservative--and, frankly, nervous--when unleashing the power in traffic. The car's output is phenomenal, and I learned that downshifting was really not necessary. Keeping it in Third gear--even in low-speed turns--saved time, thanks to the available torque. As for my `official' times, I was consistently 10 to 15 seconds slower with the ZR1 vs. the Z06. On the other hand, when exiting Turn 16 down the long straight, I was pushing 155 mph with the ZR1 but only 140 mph with the Z06. Down the main straight, the ZR1 hitnearly 140 mph before Turn 1,while the Z06 wascloser to 125 mph.
"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.