hey guys, Sorry, I have to start a thread on how to launch an auto. I'll be hellion turbocharged soon, and need a little guidence, for I'm not a racer. Thanks ahead.

 

Basically the key to launching an Automatic transmission is power braking. What you are doing in effect is preloading the transmission and driveline with torque, and increasing engine RPM so that when you start to move, the engine will be more in that sweet spot, power wise. Heres what you do, find a nice secluded stretch of road, or abandoned parking lot etc. With your left foot, apply a good amount of pressure to the brake, with your right foot quickly (But not excessively) build engine RPM, with a stock stall converter at about 2300 RPM, your tires will start to spin against the road surface, as soon as you feel or hear rubber turning on road quickly remove your left foot from the brake and begin to increase throttle, (Dont neccesarily need to floor it, as this will induce wheelspin alot of times) You can kinda imagine a slingshot analogy, as your building resistance against the drive train, and then rapidly releasing that potential energy. With a Turbo, a looser stall, (say by 500-800 RPM) will help you alot, as this will help fight dreaded Turbo lag by getting the turbine spooling up energy prior to launch. Really, the best way to learn is just to practice. Once you get it right, you can feel/hear the sweet spot where you want release brake and power the throttle. Best to turn TCS off imho as well. I hope this helps, enjoy that turbo man!
Cheers

 

Some of our cars react better to pre-loading and some of them need to have the converter flashed to get the best launch. I flash mine. Flashing is simply flooring it from an idle. You will have to practice to get your timing down as there is a bit of lag associated with this method. Flashing the converter will throw it into lock-up almost instantly. Staging it will allow slippage until the engine RPM reaches the lock-up RPM. This creates a LOT of heat. If you have not tuned, or have not changed this in your tune it is around 3400RPM from the factory at WOT. Meaning you are not putting your full power to the rear wheels until this happens. And Yes, it happens pretty quickly and is pretty hard to notice if you don't know what to look for. But for my car, I can pull a 1.84 60ft by flashing and am in the 1.90 range when I pre-load. I also understand that if I go with a higher stall converter that pre-loading is the way to go. Don't have that yet, so can't offer that info first hand.

 

not sure on the new ones but the sn95s had a 1200 rpm lock up TC, i asssume the s197s have around the same, if you really want good launches throw in a higher launching stall and a set of gears with a shift kit

 

Understand that the #'s that a torque converter is rated at is under ideal avg. driving conditions. A stall rating of say 2600rpm will not be at that once engine mods are made and varies depending on the amount of throttle given. The torque input has changed but the ratio of torque multiplication has stayed the same so the stall speed will change. Lock-up ocurs when there is some very low % of torque sensed at the converter. Meaning the cars speed has essentially caught up to the the engines power output. Then everything locks up, temps stay cooler, throttle feels responsive. Under heavy load the lock-up RPM will increase. During cruising it will be very low, mustangman says 1200rpm and that sounds about right. But under load not the case. Skunkworks said to stage at around 2300RPM...obviously things aren't locked at 2300RPM at this point..and once the car is moving there will still be slippage to right around 3400RPM which is where the cars speed has caught up enough to the engines torque to allow the converter to lock. Once mods are made the lock-up RPM will change accordingly to engine output. Flashing the converter at launch just makes the car think something else is happening. Line presure is low because you were at idle, Rpm isn't up, the converter will get to the lock-up RPM before the stall RPM, and the car thinks you are passing or something like that (for lack of a better description) and it locks the converter a few milliseconds after it sees the throttle go to WOT. Once locked it wont unlock as long as your foot is all the way in it. Try launching both ways, I will occasionally pre-load if track conditions are slippery. Allows just enough slippage off the line to "sometimes" keep the car hooked up.

 

Maybe Im understanding something.. I have an auto, and when I go to the track I dust the tires off so theyre nice and clean and sticky, just by holding the break and burning them.. same as everyone does. Then when I get up to the line I hold the break and usually slowly rev it up to about 2800-3000 and just hold it there and wait for my light... is there something wrong with my car that it is able to rev that high and not spin the tires or whats going on?

 

No not really, you just got the tires sticky and probably a very nicley prepped staging area. And I suspect you are hard on the brakes to hold it back. Thats a lot of force to overcome to get the rear to spin. But at 3000RPM you would be right on top of your stall rating with the stock converter and the mods you list Be carefull, all that torque is being held back from the wheels, your whole drivetrain is bearing the grunt of the load. I'm not sure I would be comfortable staging that high without a transbrake. And you are REALLY heating up the tranny doing this as well. I also do a burn out prior to staging.

 

Is there a better way to launch then? Maybe with line locks? It seems like I have a few weeks at least to figure out a better way since I just got caught racing by my dad and wont be doing it for awhile until I figure out how to get around it. So any info I can get on better launches in that time would be awesome.