How To Run 10s In A Stock Z06 - Maximum Acceleration, Part 2

Learn how a stock Corvette with a manual transmission and skilled driver can easily out accelerate one with fifty more horsepower piloted by an average driver.

John "Ranger" Armstrong Dec 1, 2007 0 Comment(s)

The Launch Has Three Components
1 ::: The launch rpm is held steady during release of the clutch. This pre-selected rpm is the maximum you believe prevailing track conditions will reward. An ideal launch rpm will produce just a small amount of wheelspin before the tires hook. A higher rpm would produce too much wheelspin, and a lower rpm would cause the motor to bog. With stock rear tires, the launch rpm will generally be in the range of 2,400-3,300. If you are unsure, start at 2,400 and, based on the results, adjust upward or downward in 200-300-rpm increments on the next pass. After a few runs, you will find the sweet spot that gives the right balance between wheelspin and bog.

2 ::: The clutch release should be very fast, but less than a pop or side step. The clutch pedal should be out fully before the car has moved more than 3-to-5 feet. Some drivers favor a literal pop of the pedal, termed a clutch dump. I find this more likely to break driveline parts than my approach. Other drivers prefer a slow release of the pedal to produce significant intentional clutch slip and keep the rpm elevated during the launch. I also avoid this approach because it increases clutch wear and generates unwelcome heat that can glaze the clutch entirely or cause pedal woes during the pass. This is a particular concern on the C6 Z06 because the LS7 clutch is intolerant of intentional slip at an elevated rpm.

3 ::: The throttle squeeze requires modulation and calibration to track conditions. The instant the clutch release is complete-and not before-quickly squeeze the throttle to the floor. This motion is not a stab or stomp, that would provoke excessive wheelspin, something to definitely avoid since it will slow you down and greatly increase risk of driveline breakage. Rather, the motion is a firm, deliberate squeeze with your senses focused on what the clutch and rear wheels are doing. The goal is to have the initial wheelspin from the clutch release transition quickly to a rapid rise in engine rpm without a loss of momentum or bog. Once the tires are hooked, you want the fastest squeeze achievable without provoking renewed wheelspin. The faster the squeeze, the faster the launch and 60-foot time will be. Generally, the throttle is on the floor within 20-30 feet of forward movement, depending on track conditions.

Using this three-element launch procedure, an average Corvette driver will attain 60-foot times in the 2.0s. With practice to synchronize these movements and react correctly to feedback from the car and track surface at the ragged edge of traction, a good driver will dip into the 1.9s and an excellent driver into the 1.8s.

Gear shifting should be performed fast and at the correct rpm, but more on that in a moment. A fast shift of a Corvette manual transmission can be completed in about 200 milliseconds (two-tenths of a second). So three fast shifts in a quarter-mile run (the 1st-to-2nd, 2nd-to-3rd, and 3rd-to-4th) consume six-tenths of a second with the clutch disengaged and the car not accelerating. In contrast, an average driver without the fast-shifting skill will need 400-500 milliseconds per shift, consuming 1.2-to-1.5 seconds for the three shifts; that is six- to nine-tenths slower than the fast shifter. The way to avoid the slow-shifting penalty is to practice until the act of repetitive shifting is fast, precise, confident, and, essentially, automatic.

MORE PHOTOS

VIEW FULL GALLERY

COMMENTS

subscribe to the magazine

get digital get print
TO TOP