SilverZ06Chris

What is the best launch proccedure at the track?

JerryL

Do a search for threads from Powershifter, Ranger and Steve Row. Those guys all know how it's done.

COZMONOT

I'm also curious on how to launch at the strip. My guess would to turn off
the active handling, rev to 1800 RPM's and let it rip to redline. Too bad
nobody has answered yet.

JerryL

I'll give this a stab. The challenge launching the Z06 is two-fold. Avoiding wheel hop and/or excessive wheel spin. The launch RPM is dependent on track conditions, you're going to have to experiment. Traction control should be off - many guys leave the active handling on. The best way to avoid wheel hop with the SC tires is a smooth clutch release - you can't side-step the clutch. At the line bring the RPM up to 2-3K, on green smoothly release the clutch and feed in the power. Throttle application is not accomplished like it was an on/off switch. If you stand on the gas as the clutch engages you'll spin way too much. The trick is to feed in the power over a second or two and not overwhelm the tires.

hcvone

Probably with one of those big rubber bands that the Roadrunner uses :yesnod: :yesnod: , The C5 is much harder to get off the line than my C4's were.

Ranger

In three separate posts, I'll provide quotes from good threads I've saved:

Here's a quote from a post in Apr 2001 by none other than the Bowerboy, a famous Corvette drag racer. I'll post a little follow up specific to the F1SCs later.

Begin Quote
With an old/stock clutch your options are limited. You will have to hold your RPM's below 3K and slip it slightly. If you had an upgraded clutch (not stock or Z06) I would recommend launching at 3500 to 4000RPM with a slight slip. The type of Tire you will use will also drive your launch.

If you are running stock tires, keep your launch below 2500 RPM regardless of clutch type. If you are running a drag radial, make sure you sufficiently heat them with a burnout before staging. Either way make sure your stage shallow.

The following is a description of staging shallow: The are 2 yellow lights which indicate the staging area. They are separated by 7 inches. When the track worker waves you up you approach the lights and as your car rolls you will turn on the top light first (pre-stage). As soon as the first light goes on, stop. Then slowly nudge your car forward until the second light goes on (staged). Stop immediately! When you launch your car, the clock does not start until you break the beam of both the pre-stage and stage lights (the starting line).

As soon as both lanes are staged (The staged light in each lane is lit), the first of three large yellow lights will light. On the third yellow light begin your launch. With a shallow stage. your car will have a few inches to begin rolling before the stage lights are triggered indicating you official start.

Once under way, quick shifts improve ET and MPH. Be sure to max out your RPMs without hitting the rev limiter. I shift at red-line minus 300 rpm. On your 1st to 2nd shift, power shifting (leaving your foot on the gas to the flow as you depress the clutch and make your shift) is not recommended do to traction. The 2nd to 3rd shift can realize a significant gains with a power shift however, this is the trickiest to maneuver (directional angle of the path between 2 and 3). The 3rd to 4th shift is the easiest to power shift.

Here are a few links that also may provide some info:
http://www.nhra.com/basics/basics.html
http://sl.rconcepts.com/
http://www.corvettechallenge.50megs.com/

End Quote


Ranger



[Modified by Ranger, 10:48 PM 7/2/2002]

Ranger

Second of three:

From the Corvette Program Office:

Begin Quote
First an optimum launch rpm must be established which is a function of ambient temperature, sun load, track surface, tire temperature, vehicle loading .... An optimum launch will allow enough wheel spin so that when the tires "hook up" to the pavement there is not a loss in vehicle acceleration."
End Quote

Ranger

Ranger

Third of Three:

I posted this last year. It's what I do. No claim that it is the best way.

Launching a Z06 on Stock Tires

Competition mode. AC and audio system off. Windows up. Tire pressure 44 psi in the front and 24-28 psi in the rear.

Try 2800 rpm. Increase or decrease the rpm 200-300 each run until you find the sweet spot for that pavement for that moment.

Engage the clutch over the first 2 to 10 feet of movement depending on conditions. Go WOT ONLY once the tires are hooked, and do so by squeezing the pedal progressively to the floor.

If you do so practice on old blacktop and ambient outside temp is around 75, you ought to be able to launch leaving only about 10 feet of rubber.

Another key is on the 1st-2d shift. Ease the throttle just enough to avoid a lot of wheel spin, which would hurt your time. I shift to 2d at an indicated 6200 and to 3d at 6300-6400 and to 4th at 6400. Objective is to shift as high as you can without hitting the rev-limiter.

I find that what I'm after is developing the launch "touch" that's based on input from all yours senses. I can feel the tires spin in the steering wheel, clutch foot, and seat of the pant. Sight and sound help too. But the F1SC tires don't make much of a squeal when they spin.

I use Competition mode to rather than "AH/TC off" because I want AH to intervene should the rear end get substantially out of line. Just some insurance that limits "the worst that could happen."

Two last things you probably already know. Be sure your oil is above 155 degrees (preferably above 170) before you do launch practice. Also choose your spot wisely. John Law and John Q are pretty adept at recognizing and exploiting any pattern you might set as to where and when you practice.

Ranger



[Modified by Ranger, 11:11 PM 7/2/2002]

Ranger

Why I ALWAYS Run in Competitive Mode

I posted this in Feb 2002

I've alway run in COMPETITIVE DRIVING mode at the drags. Do it on principle...It has no effect whatsoever on my times unless my rear end gets seriously out of line, at which point active handling will be invoked, thereby saving my a $ $. In such a moment, my ET would be the last thing on my mind.

Today I narrowly averted a disaster that was not of my making. AH saved my butt and vindicated my practice of running with it turned on.

I made eight passes at Capitol Raceway in Crofton Maryland. On the fourth pass, I was next in line behind a highly modified car that spewed tranny fluid on the track just after the 60’ mark. Unfortunately, no one, including me, noticed the spill as it occurred. AND, I was next.... I had my best launch of the day (1.82) and slammed 2d gear hard amidst his tranny fluid...whereupon my rear end moved violently right...toward the wall. Fortunately, Active Handling engaged and queued me to back out of the throttle immediately upon recognizing my predicament...but not before I had come within just a foot or so of the wall.

Had I turned AH off (as many people do), I surely would have hit the wall HARD. Wouldn’t have been my fault; but certainly would have spoiled the day. When that occurred, the last thing on my mind was my ET...which was a 12.81...in a day of 12.04 and a bunch of 12.1Xs, plus one trap of 118.1...all in COMPETITVE DRIVING mode.

For those interested...here is the full thread. Toward the end is a hair raising story that turned out BAD and underscores the need to keep AH ON at the drags.
http://forums.corvetteforum.com/zerothread?id=244988

Ranger

Ranger

Burn-out of BFG Drag-radials without a line-lock

No claim that what I'm doing is the best. But it seems to be working for me.

Back into the waterbox, if possible, and immediately spin the tires JUST enough to get a full rotation of them, but NOT enough to thrown much water up into the wheel wells. Roll forward out of the water. Make sure you're in COMPETITION DRIVING mode. Put the 6-speed in 2d gear. Drop the clutch and feed the throttle and quickly lightly apply the brakes with your left foot. Bring the revs to about 5000 until the tires smoke and start to grab. Release the brake and you'll roar forward. The tires are heated. I don't count seconds but just spin them until they grab hard.

Launching on BFG Drag Radials

I am holding the launch rpm (usually starting with 3600-3900 on a poorly prepped track) and then quickly but smoothly releasing the clutch with a full engage occurring over the first 4-10' of movement. I try not to feed it more throttle until I think the tires are hooked; this is the hardest part for me. There is a delicate balance to find. But as PowerShifter has written, it entails trying to squeeze the throttle progressively to the floor between 10-25 foot off the lights. The drag radials will take throttle a little quicker than the stock tires but it's still a "squeezing" action rather that just "stomping it." The other big advantage of DRs on the Z06 is that they really do a great job holding the shifts to 2d, 3d, and 4th without spinning (much). Most of my sub-12 runs have comes when the shift to 2d has almost no wheel-spin and the car feels as though it jumps forward on that shift. Ditto the shift to 3d.

Hope pulling this together in one spot is helpful.

Ranger



[Modified by Ranger, 11:21 PM 7/2/2002]

The One

Ranger - :cool: :cheers:

JC

AP

1 word:

Practice
Practice
Practice
Practice
Practice
Practice

Power Shifter

Rangers post has very good imfo IF you have some experience. If you are starting from scratch, I would recomend starting from the other end, launch just like your leaving from a trafic light agressively on the street,increase up from there as you get more runs and understand what the car will do on hard shifts, use common sence for what your trying to get the car to do. Ric

GaryZ06

This is exactly what I do.....I called it a hard street launch....my problem is the hop in 2nd in whick Ric is going to show me how to alleviate that problem....right Ric
:D :cheers: