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Launching with an AT?


1viadrft
08-30-2005, 11:47 AM
Okay... I'm trying to learn the basics here: What is the best way to lauch a car equipped with AT? The car in question is a '90 Nissan 300ZX NA. When all the mods are done I will be putting down around 210RWHP+70-shot of nitrous. I'm hoping mid-12's. A 3200 rpm stall torque convertor will also be in the mix. Maybe I don't quite understand how a higher-stall convertor works... but on an MT you want to be in 1st gear and revving before you are ready to leave the line correct? How is this possible with an AT without neutral dropping and possibly damaging the tranny? Does the hi-stall TC let you rev to (for instance) to 3200 rpm before actually engaging???

I'm a complete noob to drag-racing. I also want to get some track time before all these mods and learn how to launch an AT before I stack on more power. Any help will be greatly appreciated.

beef_bourito
08-30-2005, 12:27 PM
if you want a good launch, whatever you do, dont rev it in neutral and shift it into drive, that will destroy your tranny before long. hold the brakes down and then push the gas, rev it up to wherever you want but there is a point where it will stop (probably around 3000 if you have a 3200 stall converter).so after you rev it up and you're ready to go, take you foot off the brake pedal and hammer the gas, try to do it without spinning your tires so rev it up as high as it will go then if your tires spinn, next time rev it a little lower, keep doing this untill you find the best spot.

2of9
08-30-2005, 09:00 PM
thanks...man, i needed this help too!

1viadrft
08-30-2005, 09:25 PM
Interesting! Thanks for the tips! I shall practice-practice-practice!

beef_bourito
08-30-2005, 09:29 PM
doesn't take much practice, it just take some time to find the perfect spot, also you might not want to hammer the gas but put your foot down quickly. basically you want to get as much speed off the line without spinning your tires.

500
08-31-2005, 02:12 PM
There are really 2 ways to do it.
#1. After you get the stage lights lit you sit there with the motor at idle and somewhere around the last yellow you stomp the throttle.

#2. Load the motor against the torque convertor. Usually you are limited by the power of the brakes to keep the car from rolling. Don't put on so much throttle that you have to fight to keep the car from rolling through the beams. You have to experiment.

#1 allows the motor to flash to a higher rpm before the car starts to move [ possibly helping the ET ] but it is harder to judge where to leave on the tree to get a good, consistent RT.

#2 is easier to get good, consistent RT's but usually hurts the ET a little unless you have lots of torque and a light car.

#1 is a little easier on the trans because you don't put as much heat into the fluid.

I would be VERY surprised if your car spun the tires. Drive around the water box so you don't get any water in the treads.

beef_bourito
08-31-2005, 09:26 PM
it's really easy to spin the tires with an AT if you rev up the torque converter and drop the brakes. My moms accord v6 can spin the tires and it's not a highly modified drag car so if you have a turbocharged drag car with an at you can deffinately spin the tires, even with a 4 cylender.

500
08-31-2005, 09:33 PM
His car probably weighs 3500lbs, is rwd hopefully with a limited slip rearend, fairly wide tires and the normally aspirated motor makes all it's power at high rpm.

Your moms car is fwd with an open diff., skinny tires and a torquey motor. Real easy to spin a tire . Dragstrips are a lot stickier than public roads.

beef_bourito
08-31-2005, 09:45 PM
well, I think it could probably still do it, lets get him to do it and ask him if he could spin the tires.

AWP9521
09-01-2005, 03:32 PM
Dragstrips are a lot stickier than public roads.

If your running certain street tires a Drag Strip can be a nightmare for traction. I used to have a 95 Chrysler Concorde (got totaled in 2004) that when launched at the strip (never done a burnout, just drove around the waterbox) with the Traction Control off whether planting the gas or on the converter would spin both tires for the first 60 feet or so. You would think it had nitrous or some kind of power adder on it because it would litterally smolder the hides! On the street the car was the exact opposite, floor it from a standstill even with the Trac on and you might get a squeak of a mouse with the thing. I ended up finding out that if you launched off the rubber at the strip you had traction, launch it on the rubber and you had a nice burnout show going while trying to get the damn thing down the track.

1viadrft
09-01-2005, 04:01 PM
If I mash it I can spin the tires for a second or less... for the record my car weighs 3443lbs w/o me is indeed RWD and the motor is rather torquey.

I am getting some Yokohama Parada Spec 2 tires soon and later I am getting a DOT approved semi-slick for drag only (around the same time I get the nitrous system) and this is when I hope to get into the 12's.

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