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Thread: Launch Tips for Drag Racing- 1/4 mile

  1. #1
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    Post Launch Tips for Drag Racing- 1/4 mile

    Well, since I'm a new moderator in this forum, I thought I'd make this much copy/pasted post a sticky here...

    Here you go:

    Copy/paste from a thread in the Forced Induction Forum here about 1/4 mile times and launching....

    "I do think lowering the psi in your rear tires will make a difference. I don't know what size tires you have, but if you have the stock 245/40-17's in the rear, you want more tires on the road, not less when it comes to the 1/4 mile drag strip for launching.

    Now the standard mfgr recommended psi for 245/40-17's is 32 psi. Here's the key, you gotta play with it some. If you go too low you could have cupping, and that doesn't help either.

    I'm guessing at 245/40-17's for you, but that is my OEM size too for my car and I have run it at the track with those OEM Dunlops before (I usually run my drag radials at the track...). Anyhow, you're safe dropping them to 28 psi, no problem. You might even be able to go as low as 26 psi, maybe 25 psi, depends on the weather and the track surface temps.

    Also, for less friction/rolling resistance, take the front tires up to 45-55 psi.

    Also, for weight savings, take as much out of your car as you can. The spare tire and mounting apparatus can weigh as much as 30-40 lbs.

    Back seat, passenger seat (my passenger seat weighs like 60 lbs), any excess weight. Take the gas tank down to 1/8th a tank of gas, 1 gallon of gas can weigh like 5 lbs, run a 13-16 gallon tank down to 1/8th a tank, another 50-70 lbs, etc...

    You can shave 150-200 lbs with that kind of prep work.

    Also, try launching higher. You need to find the sweet spot, between bogging and wheelspin, and that will takes lots of practice and change from day to day, track to track, etc...

    The more traction you get from the tires, the higher you can launch your car, and you generally want to launch above torque peak so that when the tires grab, the tach drops, and if you can work the clutch right, avoid major wheelspin, you'll launch like a rocket.

    With my DR's I launch at 5500 rpm. On my OEM Dunlops more like 4500-4800 rpm at 26 psi.

    Gotta get the throttle steady when staging, an even rpm, clutch half in, half out, just about to grab, the tach dipping ever so slightly.

    When the green hits, don't slam your foot down on the gas to the floor, quickly and steadily squeeze it to the floor, and gradually but quickly let out the clutch, sense too much throttle, keep it steadily continually going down and adjust the power to the wheels with the clutch, not the gas.

    Now, if when you're shifting you're chirping your tires on every shift, you're losing maybe a tenth. In my car if I'm not careful I could get sideways on every shift, but this method can help anyone chirping on shifts too much:

    Find the appropriate amount of throttle to stab back down, then squeeze it to the floor. For me, it's about halfway, then just like on the launch, I quickly squeeze the gas pedal down. I stab halfway (versus all the way back to the floor) and quickly squeeze the pedal back down to the floor. Makes for more uneventful shifts and buys me a couple tenths in the 1/4 mile (I have to shift 3 times, I finish in 4th gear).

    Your car may work best with a 2/3rd stab then squeeze, or 3/4th throttle then the quick squeeze, all these techniques require practice and could change given the weather or the track. I take notes on all these items and then tape the timeslip next to it on a notebook page and save it for the future track visits.

    Also, if you feel like you're destroying your clutch, you're launching properly if you feel like you preserved some of it, you're not launching right... "


    I launch at 5500 rpm, pump my fronts up to 55 psi, rear drag radials down to 16-18 psi, plus all the weight shaving and cool downs in between runs...

    Whatever it takes to eek out every last tenth in my car...

  2. #2
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    It's weird I could have sworn I replied to this sticky! Anyway, it absolutely makes sense to launch above the torque peak. Then, it's up to the driver to deliver the maximum power to the wheels without losing traction. No wonder why it's so hard on clutches! I tried a couple launches but it's just too scary These are some sweet tips you give us man, thanks a bunch!

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    You're welcome! It certainly takes some getting used to, to launch "properly" at the track. No fear helps. And just remember clutches are made to wear, just like brake pads, tires, etc. They can be replaced without too much expense...

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    Can you tell me how many launches you do (frequency or whatever) and how many clutches do you go thru on a regular basis? I mean a clutch disk isn't that much but the pressure plate and flywheel ... it can add up. Oh but I bet you aren't using the stock one either...

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    100% Stock clutch. About 4300 miles on the car since I got the mods. Roughly 20-24 runs at the track in that time (since Feb 02).

    I had my 99 Mustang GT for 20K miles, for 2.5 yrs, stock clutch, maybe 40-50 runs.

    95 Z28, 36K miles, 4 yrs, probably 90-100 runs, stock clutch.

    The only clutch I have replaced was in my old 90 Z28 with the 5.0 (305) V8, replaced it at 60K miles, 5 yrs time, figure 20-25 runs a year average, been using the same launch technique for a while now....

  6. #6
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    Another copy/paste from another thread about launching....

    "Hey James,

    I'm not sure what to launch at with your car, depends on your power, where peak torque and hp occur, and what kind of tires you're running. Every car is different, and each car can be different on each different day, even at the same track.

    Generally speaking, it's a very fine/delicate balance. With my car, I'll bring the revs up nice and steady, wait until I have them perfectly steady, on a warm day, say at 5500 rpm. I'll slowly let the clutch out, right on the brink of grabbing, the tach will dip- that's the grab point.

    I'll modulate the clutch to where I can keep the revs steady again at 5500 rpm and wait for the green. Generally when the green hits, the gas pedal goes down- quickly, fast, but also gradual/fluidly. No slamming the gas down, no stabs of the pedal. Only smooth motions, no herky-jerky crap.

    As the gas pedal goes down, you gotta use your left foot to regulate the power going to the wheels. Again, all motions must be fast and fluid and smooth, but also very quick <-- that's the key.

    You gotta learn the feel of what it feels like just before your car is gonna break traction, and learn to kiss that edge without going over it, but to accomplish that you gotta push the envelope to learn and know where that edge is (and know that edge changes on each run, slightly).

    As it hooks, you gotta "feel" the clutch pedal, you'll know when to let it out all the way, if you can. Some times, I barely get the clutch pedal all the way out before it has to go down again for the shift to 2nd gear.

    You gotta do this time and time again, over and over again, to learn your car's nuances. Here's where it gets tricky- you can complete a run, cut a 1.85 60' time, come back study your notes, take 1 psi out of each rear tire and do the same thing but be able to launch higher and all of a sudden, BOOM, 1.72 60' time on the next run and shave 3 tenths off your 1/4 mile ET as a result, given you don't mess up your shifts as you go down the track.

    Was it the 1 psi less in the rear tires? Was it being able to launch at 100 rpms higher at launch? Did you shift too early on the previous runs? Or did it all simply come together on that run?

    The other key is consistency. The more consistent you can get with your runs, the better the results on the next run. Cuz you can begin to play detective and find the little things you need to tweak/correct on the next run to make it better, etc.

    It takes tons of practice. I have almost 17 yrs of practice now, and I'm no master of the technique- I'm a good drag racer, sure, but I ain't "great" <-- And that's not me being humble, that's me being totally honest and knowing my place, cuz I've seen and I know several really great drag racers who make chumps outta guys like me.

    It's part science, part art, and lots of concentration, hard work, dedication, perspiration, determination, patience, and practice-- if you find those things fun, you'll "get it" eventually.

    If you're just starting out drag racing, you'll make mistakes, don't waste a run, if you blow the launch, haul ass down the track and work on your shift points from gear to gear, etc. Take notes on everything, launch rpms, shift rpms, tire psi, front and back, try to weigh your car, if you can, get out your dyno sheet and study shift points, and adapt at the track when your calculation prove to be close but not quite right, etc...

    Most people discount drag racing as not requiring a whole lot of skill- the people who feel that way are the ones who have either never tried it, or have and aren't that good at it, and aren't willing to work at it, to become better at it, etc. It's a world of nuances and subtleties, and a couple hundred factors to consider that are often beyond your control.

    And it can be frustrating at times, you can do everything right and get crappy results- it just takes some severe stubborness and stick-to-it-iveness.

    And many people don't care about the nuances needed to get the absolute best times out of their car, even guys who have drag raced quite a bit- not everyone is going to be a student of the game and study hard, absorb all the info around them to excel at it, etc.

    Some people have the attitude of "Eh, it's only drag racing"- those people are usually not the ones who are very good at it... "

  7. #7
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    More launch tips from a PM:

    -"Should I launch at my peak torque?"

    Not neccesarily, you should launch at the highest rpm that you can without wheelspin. That's gonna vary car to car, day to day in any given car. Try to find the sweet spot for launch rpm. Try launching at 2500 rpm. If wheelspin occurs, try lower. If not, try 3000, then 3500 rpm, etc, until wheelspin occurs, then dial it in, find the best spot.

    "Also I have tried but there is no "spot" on the gas that holds it at 3500, it will just keep gaining rpm's. Should I blip the throttle on and off lightly to keep it "around"3500?"

    Hmmmm, that should not be the case. You should be able to have the clutch half in and half out at the very edge of grabbing, and be able to maintain a steady rpm with the gas. The key is to use the clutch pedal to regulate/modulate the tach to keep a steady rpm, essentially you're riding the clutch at launch to maintain a steady rpm, the gas pedal does not move, and blipping it is the worst way to launch.

    "Also when I launch it is my understanding that I should not move the gas, only the clutch and then once the clutch is fully engaged, and not spinning out, start pressing the gas down more?"

    Not exactly. The gas pedal won't move during staging if you're riding the clutch just before launch. But when the lights go green, in one fluid/smooth motion you press/squeeze the gas pedal down to the floor, gradually but quickly (don't slam it down), and use the clutch pedal to modulate/regulate any wheelspin, not the gas. The gas has to go down quickly but smoothly, use the clutch to avoid wheelspin. <--- that's the key to the perfect launch, and it takes tons upon tons of practice to master.

    "Also should I make the pressure on my rear wheels lower than recommended, and higher on the fronts? About how much?"

    Yes, generally drop the rear tires about 4-5 psi from the tire mfgr recommended specs, and raise the fronts about 10 psi above the tire mfgr recommended specs. This will give the rears a larger contact patch, more rubber on the road, and allow you to launch a little higher (rpms) cuz you'll have slightly more traction, and increase the chance of sidewall flex, which is good for launching. You can adjust the pressures and play with them, try to find the best psi for that given day (road surface and temps will dictate the best amount, etc). If you go too low cupping with occur, and defeat the purpose of getting more rubber on the road. The reason for upping the fronts is for less rolling resistance/friction.

    "And what would be good for cornering or something like a AutoX?"

    Totally different ball game, and I'm not the one to ask about that. I believe you actually up the psi in both the fronts and rears, but don't quote me on that.

    Good luck, and let me know if I can help any further!

    Dave

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    More info from some PM's about traction after launch:

    "Hi Dave,

    With the colder temps, I've had issues keeping traction in 1st gear. I've been able to do better launches w/o spinning but then once the clutch pedal is all the way out, I'm pushing down the throttle too fast and waste some time spinning (not tremendously but enough not to benefit from all of the car's power). Since you have much more power than I do, I bet you really need to be gentle with that throttle so I'd figure you could help me It's difficult to go along with the car to redline in 1st w/o spinning at all while still using all of the car's potential (I would like to accelerate at the limit of braking the tires loose).
    Any tips or suggestions? "

    Response:

    "Hey!

    What I have to do with my car is very gradually, quickly, mind you, but gradual/smooth motion, no blunt/quick motions, I sometimes find my left foot still on the clutch pedal by the time I have to shift to 2nd, and on the shift, again gradual motions, I throttle stab maybe 1/3 or 1/2 the way down on the gas pedal and then treat it like a new launch again at speed, slowly/gradually let the clutch out and gradually, but quickly press the gas pedal down to the floor. You're essentially using the clutch to regulate the power to the ground. The gas pedal motion stays consistent and gradual, other than the initial stab on the upshift, but if the clutch pedal has to remain depressed even just a little all the way thru a gear to avoid losing traction (which sometime happens in cold air racing) then so be it.

    It takes some getting used to, and seems wasteful, like you may not be getting all the power to the ground, etc, but if you're not spinning them, you're moving forward, and that should be reflected in your ET's with enough practice.

    Let me know if anything I said above makes any sense...

    Dave"

    More....

    "Thanks for the quick response! It makes a lot of sense. You are just a clutch murderer just joking. Interesting fact that you find yourself still riding the clutch during launches, never thought of that. That makes it easier to control spinning as you don't have to work with 100% of your car's power, it works as some sort of dampener even at speed and that's what I missed. I thought you had to get rid of riding the clutch asap but that's not true.
    Thanks again! Can't wait to put into practice."

    Response:

    "Yeah, man! I sometimes still have my left foot on the clutch like 10% on the 3rd to 4th shift at 90+ mph if need be... "

  9. #9
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    That is good advice for launching and getting the most out of your car, but I would try to keep the interior in place so you know what time you are running on the street.

    How often do you ride around with your seats out and interior stripped down?

  10. #10
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    How about some tips for us unfortuante souls with a slushbox???

    1998 Corvette"Mod fever"...

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    Sven, BFG makes a 255-50-16 DR for you...

    Auto's- similar principle. Get the revs up as high as you can (you can't regulate power to the ground with a 3rd pedal) but you have to use the brake with your left foot, find the place where the wheels just start to break traction.

    Line lock it to find that place. Then start over, find that rpm again. The light goes green remove your left foot from the brake pedal. Again, like with stick cars, quickly but gradually push the gas pedal to the floor. Don't slam it down. If you do you'll likely spin 'em. If you do slam it down and the car takes off without any wheelspin- you weren't revving high enough when you let the brake off.

    You want to be at the absolute limit where you are about to break traction, but not inducing wheelspin.

    From there, it depend on your automatic. Some tranny's- you're better off shifting it yourself from gear to gear, others, you're better off just holding the gas down all the way down the 1320. Watch where your tranny upshifts under full throttle. If it shifts early, or over revs for any reason- take the matter into your own hands and practice upshifting it yourself.

    I don't know if anyone makes stall convertors and shift kits for auto tranny BMWs, like they do for Fords and Chevys, but that might be something to look into too....


    tubbedF100- the purpose of this thread was launch techniques I have used over the years to achieve the best possible times at the Track- hence, wht it's in the Track Forum. I'm a believer in finding a way to eeek out every last tenth in my car at the track.

    But one thing I have learned since owning a BMW, besides that fact that I'm a drag racing freak , is that since most BMW owners aren't avid drag racers, I hear that a lot, "Well, what's it really run in the real world with out your weight reduction and with street tires on it???"

    I'm always a bit baffled by this, cuz I'm not sure why it matters. I mean I do engage in the occassional street race, but for the most part street races aren't accurate measures of anything-- not like a track with proper timing equipment and a more closed (and much safer) environment. I've never been real concerned with what my car runs on the street cuz it's not a closed environment, impossible to predict and reproduce due to hundreds of factors (road conditions, turns, hills, traffic and other safety concerns).

    However, that being said, at the behest of my BMW-brethren, I have decided that this Spring I will track my car one day in full street trim- more for shits and giggles than anything else, and maybe also just to appease my non-drag-racing critics out there who often try to put my car into a "special category" cuz I happen to be an experienced drag racer who knows how to prep a car at the track and get the most out of it...

    Again, the purpose of this thread is Launch Tips & Techniques for Drag Racing at the 1/4 mile TRACK, not street...

  12. #12
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    If I stand on the brake and rev it, won't I kill the TC?? Or the Auto tranny?


    The BFG won't fit on my rim as I have 16x7, however, I'm thinking about getting a couple 16x7.5....

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    16x8's would be even better for 255/50-16's.

    You will wear/tear on the TC quite a bit, yes. Much like I wear on my clutch. No one said Drag Racing was "good" for your car...

  14. #14
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    Originally posted by SilverStreak

    Again, the purpose of this thread is Launch Tips & Techniques for Drag Racing at the 1/4 mile TRACK, not street...
    Well said.

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    1 gallon of gas can weigh like 5 lbs,
    To be exact, 1 gallon of gas weighs 8.7 lbs silver.

    As for the person who asked for tips launching an auto, this might help. I found the optimum launch in a 330i step to be 1600 rpm. No higher, unless you have aftermarket wider tires. If you go higher, you will spin, unless you do not slam your foot to the floor. I would launch at 1600 and slam my foot to the floor and had my best results this way.

    Silver, how long should the burnout be with street tires and does it help with traction much?

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    What times do you guys that run at the strip get? I have a '90 S-10 Blazer with a 350 in it and I run low 12's. I have a OD auto w/3000 stall converter which helps on the launches. I can get a little air under the fronts with slicks and a big cloud of smoke on radials.

    How good does the Bimmer IRS work at launch as far as squat and toe in/out problems. Can you install harder bushings or even aluminum ones to take the flex out? Someday I hope to install a Twin Turbo 427 LS1 w/6speed into a 318 to kill all the rice grinders around town.
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  17. #17
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    Sticky, thanks for the clarification, I think I meant to say "about 7.5 lbs" but even still, a good correction.

    Burnouts on street tires- just enough to clean them off, they won't heat up like a drag radial or slick will, so you don't have to do it for as long.

  18. #18
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    Question

    WHen you say you launch at xxxx RPM; how do u launch? Do you rev up to that amount and then go into first and squezze on accel?


    Second, when you say you .................................................. .................................................. .................................................. .....................................oh, switch at half-way does that mean you don't bring your foot of accel totaly to switch gears? So you bring accelerator only 1/2 way up then? but just enough so you can engage next gear?

  19. #19
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    I'm sorry, can you be more clear in the questions you are asking? I'm not quite understanding what it is your asking, exactly?

    When I say I launch at 5500 rpm, that means the clutch pedal is down to the floor, the shifter in 1st gear, the gas pedal is being pushed to the point where the tach is at a steady 5500 rpm, and the clutch pedal is being raised off the floor to the point where it is about to grab. At that point, where it's starting to grab, I re-adjust both pedals until I get a steady reading on the tach (no needle jump or power surges), then I sit there, keeping it revved, with the clutch burning until the tree lights the green.

    I'm not sure what your 2nd question was addressing????

  20. #20
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    k, i understand now, second Q is...


    basically, do u lift your foot off the accelerator fully to switch gears or do u bring it up 1/2 way then clutch - switch gears?....i thought i read somewhere bout you bringing your foot up 1/2 way on it.

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    I see. It depends, gear to gear, shift to shift, and the traction that is available. Not to give you the short answer, but what I mean to say is: it depends.

    You gotta gauge it on the fly and adapt/adjust your style on each shift on each run accordingly. It's one of the annoying little nuances to drag racing.

    If traction is good, maybe in the upper gears, like on the 2-3 shift or 3-4 shift, you can lift your foot off the gas pedal 100%, clutch in, shift, throttle stab according to available traction (50%, 75%) etc.

    If traction is limited, maybe your foot only comes up halfway, and the clutch never makes it fully out before the shift, and you can't even afford the throttle stab after the shift...

    It depends...

  22. #22
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    PS- This is prime example of why real life experience at the track is so valuable. There are certain things you have to experience and gauge for yourself. We can sit here and talk about it 9 ways to Sundays, but it still remains to be all theory without practice, which amounts to no real value.

    You gotta get out there, and try this stuff, practice, practice, practice, there is no quick and easy solution. It takes lots of time to get this stuff down, and you'll still screw up.

    Also, keep in mind, these tips are things that work for me, things that I have developed over the years, my personal style of drag racing. And with that, they may not work for everyone. You need to get out there and do it for yourself, and develop your own style...

  23. #23
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    but it costs money

  24. #24
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    No one said it was easy...

  25. #25
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    Originally posted by SilverStreak
    No one said it was easy...
    :

    Wanna get humbled? Run your mouth before ever having been to the strip about how you expect a 14.2 time, especially since you have a CAI and chip in a 95 M3.

    Then go out and run a 15.1 on your first run, never getting better than a 14.4.

    That oughta do the trick...
    Aaron aka "Ron" aka A-Mac

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