|Dragstrip and Launch Techniques Discussion 1/4 mile, 1/8 mile, launch discussions.|
|10-24-2011, 09:36 PM||#1|
knows 2 facts about ducks
Drives: ...and they're both wrong
Join Date: Aug 2009
Location: The HMS Invincible
Some Helpful Tips for Drag Racing
Now I did not write this, 2SSRS just sent me the link and I realized that their is a TON of information on the site.
Here's a quote from a 2001 post by the Bowerboy, a famous Corvette drag racer.
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's a link that provides some useful info:
NHRA Drag Racing Basics
Burnout Without a Line-lock--The Procedure
Drag radial tires must be heated by a burnout or else they'll provide traction no better than a stock tire. I've found through experimentation that stock tires too benefit from some heat. This only matters once driving is dialed-in. But heating the stock tires by a burnout will improve traction on launch and shifts. Here is the procedure.
Put car in Competitive Driving mode (C5 Corvette) or TC-Off (C6 Corvette). Other platforms should use the setting that disables traction-control but retains stability control.
Drive around the water. Keep the front tires dry, Otherwise, your heated rears will drive through the water trail left by wet fronts on the way to the line.
Back into the damp area, not the wet area. Back up enough to get 3/4 or more of the tire tread damp. Don't spin the tires in the water. You just want to get most of the tread with a sheen of water.
Roll forward to the leading edge of the damp area. Start the burnout there. Do NOT roll so far as to put the rear wheels onto the heavy sticky rubber/VHT prepped area. The car should start and finish the burnout with no more that a foot or so of forward movement.
Put the tranny in 2d gear. This will enable the tires to heat faster, because they’ll spin at a higher indicated mph. Since the tires are damp, they spin quite easily in 2d. Some owners prefer first gear. And that's OK.
Rev the motor to 3500 and pop the clutch. Immediately lightly apply the brakes with your left foot. The brakes help keep the rear-end from walking sideways.
Bring the rpm to about 5000 and hold it there until the drag radials smoke strongly and start to drag down the rpm. At that point, back out of the throttle and release the brakes. You'll roar forward. The tires are heated. For stock tires, spin them only to first smoke. It is helpful to adjust the driver’s outside mirror to view the left rear wheel/smoke.
Warning: if you botch the burn-out, don't retry it with dry tires. Doing that will likely glaze the clutch...or…break an axle. Instead, start again at Step 3, by rewetting the rear tires.
Practice will help get the synchronization of the foot movements.
You can practice in a level asphalt parking lot with water from a couple gallon jugs.Draw a couple lines with chalk to help establish an alignment guide. Pour out three or four gallons of water generally at the wheel points. Voila. You’ve got a pseudo water-box. An observer/spotter is a plus.
Don’t worry about brake wear. Five seconds on the brakes is like braking 60-10. You do that every time you drive the car.
Burn-out of BFG Drag-radials without a line-lock
Here is what I'm doing; no claim it's the best way.
Back into the waterbox if possible and immediately spin the tires just enough to get a full rotation of them, but NOT enough to throw (much) water up into the wheel wells.
Roll forward out of the water few feet; but do NOT roll so far as to put the rear wheels onto the rubber/VHT prepped area.
Make sure you're in COMPETITIVE DRIVING mode. Put the 6-speed in 2d gear.
Drop the clutch and feed the throttle and (if necessary), quickly lightly apply the brakes with your left foot. I donÕt usually need the brakes but some folks find it helpful for keeping the rear end from walking sideways.
Bring the rpm to about 6000 until the tires smoke strongly and start to grab and the rpm starts falling. At that point, back out of the throttle and (if applied) release the brake, and you'll roar forward. The tires are heated. I don't count seconds but just spin them strongly until they grab hard.
Takes a little practice. But remember, if you botch the burn-out, DON'T retry it with dry tires. Doing that will likely glaze the clutch...or worse.
Burn-out of Stock Tires
After you have accumulated 30+ passes and have started to produce consistent 60' and ETs, you will want to find a way to improve. Here is one way....
If you are running the stock Z06 tires (GY F1SCs), a full burnout will lower your 60' times, all other things being equal.
Avoid driving THROUGH the water. Instead drive around the water and back up until the rear tires are just into the damp area. I then do a full burnout just like on DRs. I don't have a line lock and here is my procedure (no claim it's the best way):
Back into the damp area forward of the waterbox.
Make sure you're in COMPETITIVE DRIVING mode. Put the tranny in 2d.
Drop the clutch and feed the throttle and (if necessary), quickly lightly apply the brakes with your left foot. I don't usually need the brakes but some folks find it helpful for keeping the rear end from walking to far sideways.
Bring the rpm to about 6000 until the tires smoke strongly. At that point, back out of the throttle and (if applied) release the brake, and you'll roar forward. The tires are heated. I don't count seconds but just spin them strongly until they smoke hard.
Takes a little practice. But remember, if you botch the burn-out, DON'T retry it with dry tires. Doing that will likely glaze the clutch...or worse.
Using this procedure, I'm usually getting high 1.7s or low 1.8s on stock tires. That is about a tenth improvement compared to what I was getting with a simple clean-up spin before staging. The burnout also helps to better hook the shifts to 2d and 3d.
The Essence of Launch
Before doing launches at the track, you need to turn off Traction Control. You want the setting that allows wheel spin but retains Active Handling/Stability Control.
In a C5 Corvette you want to be in Competitive Driving mode.
In a C6 Corvette you want to be in Traction System Off mode.
Other platforms will have different descriptive settings.
Lower your stock rear tire pressure to about 25 psi (hot).
The exact pressure varies by platform, tire model, and track conditions. The goal is to remove 15-20% of the air, again "hot." This will increase the size of the tire's contact patch with the launch surface and cushion the shock to the drive line on launch and shifts.
I recommend a launch procedure with three deliberate elements that are inter-related and must be coordinated.
(1) launch rpm
(2) clutch release
(3) throttle squeeze
Hold the launch rpm and then quickly but smoothly release the clutch with full engagement occurring over the first 3-10 feet of forward movement, depending on conditions.
Don't feed more throttle until the tires are hooked.
Then and only then, squeeze the throttle progressively to the floor.
Drag radials will take throttle quicker than stock tires but even on DRs it's still a "squeezing" action rather that just "hammering it" to the floor in one movement.
The goal is getting a bit of wheel spin which gives way to a rapid rise in engine rpm, rather than a bog. If it bogs, raise the launch rpm a few hundred on the next time. If it spins too much, lower the launch rpm a few hundred on the next pass.
Finally, it takes seat time and passes to embed the techniques in muscle memory and learn to read what surface conditions dictate on any particular day.
I urge avoiding the classic launch error: engaging the clutch and hammering the throttle simultaneously.
Launching on Stock Tires
Here is what I do. No claim it's the best way.
Competition mode. AC and audio system off. Windows up. Tire pressure 44-48 psi (front); 24-28 psi (rear).
Try 2800 rpm. Increase or decrease the rpm 200-300 each run until you find the sweet spot for your conditions.
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 some 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 will hurt your time. When I began drag racing the Z06, I shifted to 2d at an indicated 6200, 3d at 6300-6400 and 4th at 6400. Objective is to shift as high as you can without hitting the rev-limiter.
What you are after is developing the launch "touch" combining input from all yours senses. I can feel the tires spin in the steering wheel, clutch pedal, 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 rather than "AH/TC off" because I want AH to intervene should the rear get substantially out of line. Just some insurance to limits "the worst that can 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.
Launch on BFG Drag Radials
I hold the launch rpm (usually starting with 3600-3900 on an average 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. There is a delicate balance to find. But it entails squeezing the throttle progressively to the floor between 10-25 foot off the lights. Drag radials will take throttle more quickly than stock tires, but it's still a "squeezing" action rather that a "stomp." Another big advantage of DRs is that they 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 little wheel-spin and the car feels as though it jumps forward on that shift. Ditto the shift to 3d.
Drills to Improve Shift Speed and Accuracy
Conduct these drills with the car parked and engine off. But before beginning, drive the car to warm up the driveline, particularly the transmission fluid, for which an oil temperature of 100 degrees is a good surrogate benchmark.
Wear your shifter glove and racing shoes. Restore the driver’s seat and steering wheel to your pre-set race positions. With those preparatory actions completed, you are ready to start the drills.
Step-1 Check and adjust your hand position on the shifter.
My advice is to keep your thumb off the shifter. Missed shifts often result from a driver’s five-finger death-grip on the shifter, which introduces unintended lateral movement that misses shift-gates widely.
Pull the shifter with cupped fingers, no thumb.
Push the shifter with the heel of the hand, no fingers.
Pull the shifter straight back; remember cupped fingers and no thumb.
Push the shifter toward the radio; remember heel of the hand and no thumb. This will allow the shifter’s strong centering device to find the 3d-gear shift gate.
Pull the shifter straight back; remember cupped fingers and no thumb, same as the 1st-to-2d.
Step-2 Conduct shifting drills, using the Step-1 hand positions.
The key to strong shifts under heavy acceleration without missing them is practice.
For each shift, there are five movements: clutch-in and throttle-lift; gear-change; clutch-out and throttle-down. It takes practice to get the moving parts of each shift synchronized, integrated and executed in minimal time.
Now do the full shifts with complete movements…
3d-to-4th..pause. That constitutes one repetition. I suggest five repetitions per set and two sets per session.
4th-to-5th...If you are practicing for a dash to max speed at an airfield event, then add this shift too. The hand position is the same as for 2d-to-3d.
I do at least 20 sets of this drill per week, usually two sets at each end of my daily commute, and two sets in the staging lanes at the drag strip before each pass. This routine embeds muscle memory and makes each shift a preparatory cue for the next. Consistent practice will put an end to missed shifts for most drivers and make each shift much faster and nearly automatic. That in turn will free the mind to focus on shift points.
Why I ALWAYS Run in "Competitive Driving" Mode
I posted this in Feb 2002
I've always 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 COMPETITIVE DRIVING mode.
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. COMPETITIVE DRIVING Mode at the Drags--Disaster Avoided
Another post about my "wall incident":
The "queue" from AH means that within fractions of a second (literally) (1) my rear end moved violently right toward the wall and (2) AH immediately invoked countervailing action. Both produced sensory inputs that deviated from the norm and I backed out of the throttle. The car came straight again nearly against the wall. It had moved right about 12 feet. Total time of the event was around half a second.
I also made some steering correction, but AH played two roles (1) its pulsing actions queued my senses and (2) it took positive countervailing action to correct the out-of-line condition. Given that AH makes corrective adjustments many times in a tenth of a second, it certainly was the dominant factor in my staying off the wall. True, I backed off the throttle, but not until the accumulating sensory inputs caused me to recognize my predicament; but in those crucial tenths of a second AH had already been in action.
Lota folks can recover from just "loose." But few (without AH ON) can recover successfully from "violently loose." You may be one who can, I'm not.
On Power shifting
I don't recommend power shifting until you accumulate a lot of passes. Up to that point, there are plenty of things to work on to reduce your ET without incurring the risks to your tranny that power shifting entails. Once you've wrung all the time-wastage out of your passes, then power shifting may me necessary to reduce your times further. But I'm not yet at that point except in unusual conditions.....
|10-24-2011, 09:56 PM||#2|
Join Date: Sep 2009
Location: Edison New Jersey
WOW! A lot of good stuff here. Thanks for posting!
Vortech V3 Polished Supercharger Kit, Dynatech 1 7/8" Coated Headers, Street Slayer Twin Carbon Clutch,DSS 1000HP Axles, Jannetty 4:10 Rear with Posi Mod,MGW Short Shifter with White Retro Knob, Race Ready Exhaust Cutouts, BMR Trailing Arms, Separate Clutch Reservoir, Tick Clutch Line, Tick Clutch Bleeder, ZL1 Pedal Covers
BUILT BY IDEAL GARAGE TUNED BY JANNETTY RACING 1/8 Mile email@example.com 1/4 Mile firstname.lastname@example.org BoneStock Best time on DR's 11.60@124MPH
|10-24-2011, 11:45 PM||#3|
Lots of great information... Thanks for posting... Not all of these techniques will be used by everyong obviously, but if it allows you time to reflect on why you do or dont do the things you do... then it's a benefit...
Great Find Steiger
Horsepower is how fast you hit the wall.
Torque is how far you take the wall with you.
“If everything seems under control, you're just not going fast enough.” Mario Andretti
If you can turn, you ain't going fast enough...
|10-30-2011, 04:35 PM||#5|
Camaro SS Lover
Drives: 2010 Camaro 2SS/RS Black IOM
Join Date: Jun 2010
Location: Toronto, Ontario (Canada)
This is awesome. I always wondered how it was done without a line lock.
|10-30-2011, 04:40 PM||#6|
Drives: Synergy LS & Vulcan 1600cc
Join Date: Apr 2011
Location: Lakeland, Florida
i go to the tracks all the time, and the one thing I wanna add that I believe you forgot to mention was that your hit foot should hit the gas peddle instead of the break when launching.
|11-01-2011, 12:16 AM||#7|
Don't Like it? Suggit.
Drives: 2010 2SS/RS
Join Date: Aug 2008
Location: Fresno, CA
Great thread man, thanks for posting
"Tops off, tach up baby- loud and proud!"
A Camaro lover from day one- 1996 3.8 V6 Camaro, to 1996 5.7 LT1 Camaro Z28, to the sold 2002 5.7 LS1 Camaro SS, and NOW, a [I]6.2 L99 VR 2SS/RS: XS Power stainless full exhaust, Airaid CAI, BMR drop springs and sways, custom tune by Cal Speed- 411rwhp
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