Want stronger acceleration from your Corvette? Who doesn't! The traditional prescription to modify any car is by adding horsepower, stickier tires, and, perhaps, more favorable gearing. But there is another path to faster acceleration, and it's cheap by comparison. It's learning to drive the car better, by adopting optimal driver techniques that can extract all the performance Chevy has already built into your car.
This is part one of a Corvette Fever special three-part series focusing on driving techniques for maximum acceleration in a six-speed Corvette. John Armstrong, well known as "Ranger" on the Corvette Forum and other Internet fast-driving communities, has set quarter-mile records in three different Z06s. And last fall in his '06 Z06, he set the all-time record for stock Corvettes on drag radial tires at 10.85 at 129.50 mph. He's also run 11.24/127.03 on the stock run-flat tires, five-tenths of a second under the Chevy specification for the Z06-that equates to about a six car-length improvement.
In part one, we have asked John to share with Corvette Fever readers his background driving Corvettes. In part two, he will describe his specific techniques for achieving maximum acceleration. Part three, hopefully, will be a shootout featuring John driving a stock C6 Z06 against some legendary Corvettes set up for the dragstrip. This last segment is still in the planning stages at this printing so keep your fingers crossed.
John shares,My life changed for the better back in 1960 when someone at Williams Chevrolet in Milford, Ohio, neglected to lock a door on a newly arrived Corvette. The car was white and hypnotically beautiful in the moonlight. I dropped the kickstand on my bicycle, tried the driver's door, squealed yippee when it opened, and climbed in. I was only 14 years old, but I spent a long time that night shifting through the gears, clutch in, clutch out-1-2, 2-3, 3-4, and then repeated the process, over and over. I shifted until my clutch leg got tired, rested, and did it all over again. From that day on, I knew Corvettes were in my future.
The Corvette dream became a reality as graduation from West Point approached, and I bought my first car. My choice was a new '68 Corvette convertible with the 427/435hp engine, four-speed transmission, and 3.70 rearend. It was among the fastest production cars of the day. That summer I drove the '68 427 on my first ten passes at the dragstrip, old Edgewater near Cincinnati. My best runs, all stock including the tires, were 13.4-13.5 seconds e.t. at a trap speed of 109 mph.
The L71 Corvette demanded finesse with the clutch and throttle because its narrow tires were easy to blow away on launch and shifts. I learned to focus on traction to avoid losing match races with the 427 Fords and the Hemi Dodges I encountered on the street. I also experienced the perils of driver error, trashing one transmission by a missed shift. The root cause: wearing slick, leather-soled shoes while hammering through the gears. Fortunately for me, Chevy covered replacement of that M21 transmission. that incident remains my only driver-induced breakage in a Corvette.
On departing to fight in the Vietnam war, I left the Corvette for my mother to sell. Turned out she sold it to Roger Penske, a legendary racer even then. He flew into town, inspected and testdrove my car, wrote mom a check for the asking price, and then drove that Corvette away . . . all in 20 minutes. Penske moved fast.
Thirty-three years later, my interest in drag racing was rekindled quite accidentally. In the spring of 2001, while on a Sunday solo cruise in my Z06 (stock except for a cold-air intake), I happened by a Maryland dragstrip called Capitol Raceway. In a fateful, spur-of-the-moment decision, I turned in the gate and went through technical inspection successfully. I just had to promise the inspector I'd scrounge up a helmet the rules required.
Decades had gone by since my last pass down the 1320 and apprehension weighed heavily on my mind. Would I remember what to do? But that concern was trumped by my desire to see if an ordinary owner could match Chevy's '01 Z06 quarter-mile specification of 12.6 at 114 mph. After getting a quick brief on staging procedures from an experienced driver and borrowing his helmet, I staged the Z06. First pass was 12.53 at 116.24 mph. Then four more, all but one beating the Z06 spec. My best run that day was 12.47 at 117.39 mph. I was pumped.
It was particularly reassuring that lessons I'd learned in the '68 427 were still embedded in my instincts and muscle memory, and they remained relevant. Traction was still crucial; the clutch and throttle still required finesse; and fast, precise shifts at the right rpm remained keys to the e.t. And this time I was wearing rubber-soled shoes with a good grip.
The results of my belated return to the dragstrip presented an opportunity. I might be the right guy to find out how quick and fast a Z06 could be. I just needed to optimize my driving while keeping the car unchanged. After mulling it over a few days, the perceived opportunity became the quest.
A committed, rigorous engineering approach was needed to identify the optimal techniques for absolute best acceleration. What I lacked in traditional on-board data acquisition hardware and the support of a professional team, I had to make up for in life experience. That included an engineering degree, 25 years of analytical and program management experience in the intelligence services, and six years running a software company. My physical fitness would help, too.
With the goal now set, my attention turned to making passes at my local strip, building a comprehensive logbook, and learning from the performance data I collected. Over the next nine months, I accumulated about 100 passes in that first Z06, refining techniques, grooving my launch and shift skills, and chipping away at the e.t. Still on stock tires, the progression was 12.42, 12.35, 12.29, and then 12.14. Along the way, I learned to ignore the car in the other lane and just run my own pass. For my purposes, bracket racing would be a distraction.
On the final day of the '01 racing season, I mounted my first pair of drag radial (DR) tires on the car and headed for Capitol Raceway. I got some badly needed last-minute coaching on the burnout procedure for heating the DRs. I then cranked out an 11.94 at 116.65-mph pass and received the coveted 11-second timeslip on literally my last pass of the season. That 11.94 run remains the record for an '01 Z06 with just a cold-air intake and drag radials.
Six months later, I made the transition to an '02 Z06 with its 405hp motor and a Chevy quarter-mile spec of 12.4 at 116 mph. My first day at the drags, with 515 miles on the odometer and still on paper tags, the car ran a 12.16 at 116.47 mph, stock on the stock tires. Seventeen months and 200 passes later, it ran 11.81 at 117.26 mph, the record at the time, though later eclipsed by 0.03 seconds by another driver.
I campaigned the car at three different tracks most weekends during the fall of 2002 with the car sporting just a cold-air intake and drag radials. My driving improved as I continued to wring wastage from my techniques. And my e.t.'s continued to drop: 11.82, 11.72, 11.68, 11.61, and, finally, 11.55 at 117.69 mph. This latter pass is on video and remains the best run I've ever driven. the elusive perfect pass was made with 363 rear-wheel horsepower in average weather conditions.
I invested another 150 passes in that car and only eked out three more hundredths. But the additional experience brought strong consistency to my driving. On the final day of my '04 season at Atco Raceway, I ran four passes within five one-hundredths of a second, the best being 11.53 at 119.79 mph. The previous week at Capitol, I set what remains the record for a stock '02-and-later Z06 with a cold-air intake and drag radials: 11.52 at 120.21 mph. Records are made to be broken, and someone will break that one someday. Hopefully, it will be captured on video because I'll want to see it.
As an outgrowth of this quest, I have continued to write and post acceleration technique guidance on several Internet sites catering to driving enthusiasts, particularly the Corvette Forum. My body of writing has helped other owners leverage the learning curve I've already ridden. Not surprisingly I guess, these tutorials spawned new demands on my time to answer questions from around the country and overseas. It became clear that thousands of Corvette owners want to improve their acceleration skills. Their positive feedback to my writing reinforced my commitment to the quest.
In early 2006, I transitioned to the 427ci, 505hp C6 Z06 with its Chevy quarter-mile spec of 11.7 at 125 mph. As everyone knows by now, the car lives up to its billing as the fastest production vehicle GM has ever sold, at least so far. The C6 Z06 is a more difficult car to drive than its C5 counterpart. There are three major challenges a new owner must overcome. First, the C6Z's extra 100 hp demands added finesse, lest the tires spin excessively on launch and shifts. Second, the LS7 clutch is simply intolerant of an aggressive launch. Even slight slipping of the clutch on a 3,000-rpm launch will glaze the clutch and hang the clutch pedal midway up. This forces an aborted run and parking to cool down the clutch. Third, the LS7 engine management computer (ECU/PCM) features a devilishly clever function called Torque Management (TM) that reduces engine power to protect the drivetrain under certain conditions involving strong acceleration. A driver can really feel that momentary power loss when the TM is invoked. These three changes combine to make the C6Z a difficult car to drive well at the limit.
With that as background, the techniques I'd honed through 500 passes in C5Zs needed revision when I hit the track in the C6Z. My first day at Maryland International Raceway, running stock on drag radials, my new Z06 hung the clutch pedal on its first launch. I cooled the clutch down and adjusted my launch procedures. On the fourth pass, I ran an 11.31 at 126.92 mph. The next day at Capitol, the progression was 11.38, 11.36, 11.28, and 11.20. I was disappointed. The 11.20 was only three-tenths of a second faster than I'd run in the '02 Z06 with 100 less horsepower. It was obvious I had some learning to do.
Unless the driver of any traction-limited, manual-tranny car is told the optimal driving techniques, he generally will need at least 30-50 passes to discover them independently. By pass number 37 in the C6Z, I had dropped the stock-tire e.t. to 11.24 at 127.03. But bedeviled by the finicky LS7 clutch and Torque Management, I'd hit a plateau at 11.20 on the drag radials.
My remediation effort involved ten pure R&D passes focused on launch techniques and different tire combinations. The problem was confined to my launch and the 1-2 shift, the first 200 feet of the 1320. The rest of the pass was very consistent and fast enough to support dropping into the 10-second range. This methodical approach yielded the adjustments I needed.
My subsequent passes were: 11.16, 11.12, 11.10, 11.08, 11.06, 11.03, and finally, on my 52nd pass in the car, a 10.85 at 129.50. This latter pass is the all-time record for a stock Corvette on drag radials. And it was not perfectly driven. The one driver error was an early 2-3 shift, 300 rpm short of target. What would be the outcome of the elusive perfect pass in a stock C6Z on drag radials? My estimate is the high 10.7s.
I close by highlighting an unfortunate consequence of running fast times in a stock C6Z. It puts the driver in violation of NHRA and IHRA safety rules that require a rollbar on cars running quicker than 11.50. Although track officials generally have some latitude, they frequently "boot" a driver for the day for running two passes under 11.50. Repeated "bootings" can lead to a permanent ban from a particular track, as I've learned the hard way.
Some "experts" advise biting the bullet and installing the rollbar in a stock Z06. But for daily-driven cars that would mean the drivers and passengers would need to wear helmets on the street to protect their heads from hitting the rollbar tubing in the event of an accident. By the experts' logic, safety at the track should take priority over safety on the street. That seems an imprudent trade-off.
I mention this issue because it will confront more Corvette owners as Chevy continues to give us the horsepower we want. As the fastest stock production cars continue to get even faster, the NHRA and IHRA will need to revise the rules to give owners of these stock cars, like mine, a safe place to race.
In part two next month, I'll be sharing the techniques I've learned for Ranger-style max acceleration through 550-plus passes at the dragstrip.
John "Ranger" Armstrong is producing a DVD on the aforementioned techniques for maximum acceleration in Corvettes. Scheduled for release the fourth quarter of 2007 via his web site (www.rangeracceleration.com), the DVD is intended to help Corvette owners get the most from their cars in a straight line, on the street and at the dragstrip.