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Old 20th May 2009, 12:04   #1
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Default The perfect Launch in an AUTOMATIC !

I searched for a similar thread couldn't find one hence starting a new one.

How would you launch an automatic car for a quarter mile drag.
  1. Would you wait for the signal and just step on it (Floor it).
  2. Or Would you hold brakes down and keep the throttle pedal floored a few seconds before launch to ensure the car (torque-convertor) is already spooled up to the meaty part of the rev range, and at the last sec. release brakes.
In the manuals thats what you would you right, clutch depressed keep revs high and at the signal slip the clutch for that perfect launch.

Th reason I ask is that I have a wager with my Boss on which car would be faster in a quarter mile The Accord 3.0 V6 (2005), or the BMW 525i (2008).

I mostly would be driving the V6 with him in the 525i,..I just didn't want to screw up in the launch. I am sure he will cheat by going tip tronic,..no such luck on the accord (No paddle shifters in this one).

Disclaimer:- I condone street racing and this is not going to be done on any thuroughfare and certainly not at night.

Last edited by Torque-ative : 20th May 2009 at 12:08. Reason: Typo
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Old 20th May 2009, 12:10   #2
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My personal opinion would be put in Drive and keep the brakes pressed..and once u get the green.. just press hard on gas....and let the automatic do the thingy...
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Old 20th May 2009, 12:11   #3
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I would answer it in 3 parts

1. I would certainly like to got with the seconde option but would also depend on the kind of tyres & tarmac you would not want to do it on certain kind of indian roads!!!

2. Yes, if you are revving your engine & if tryes are spinning & are at optimum temperature they would have more grip & traction & will enable you to pick speed up better

3. I personally feel Accord would not be a mtch for BMW 5 series, that my personal perception , so if Honda is your own car, go easy with it.
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Old 20th May 2009, 12:14   #4
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Wow! you really want to win against your boss ?

The only automatic's I've driven are a previous generation Toyota corolla, a '07 Mustang and a Chevy Cobalt. IMO - they were all faster off the lights with the second approach that you mentioned.

I guess the correct RPM for launch would be where the engine produces the most torque - same as on manual cars.

Waiting for more opinions to pour in.
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Old 20th May 2009, 12:21   #5
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The 525i is a handler and has a quick gear box = Great for twisties and accord is no match here.

The 3.0 V6 on the other hand drops its load in a straight line, thats where the argument started.

Both cars are his, so no question going easy
But seriously whats the right thing to do technically ?
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Old 20th May 2009, 12:40   #6
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When launching a car with an automatic transmission, a technique called power braking is used. After properly staging the car at the drag strip’s staging lane, tightly hold down the brake with one foot, while slowly applying the accelerator peddle with the other foot. The car’s engine RPM (revolutions per minute) should slowly increase to a point where the car will either start to move or start spinning the tires. Hold down both the brake and accelerator peddles just below the point where the car is starting to move or spinning the tires. When the christmas tree lights reach the last amber light before the green, lift off of the brake and slowly push the gas peddle all the way down. The correct RPM to launch at will be different every car depending on all of the variables mentioned earlier. Start conservative with the first launch and keep increasing the RPM at which the car is launched at during the subsequent runs. If the car starts spinning the tires after the launch, lower the launch RPM and try again.

Source: Drag Racing - The Perfect Launch
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Old 20th May 2009, 13:25   #7
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Thanks Vikram,...does this apply to front wheel drive cars as well,...since the V6 is FWD.
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Old 20th May 2009, 13:32   #8
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ive tried the 2nd way in my friends a6. except that when the brake is depressed the revs are limited to 4k rpm. didnt really try it properly. i think that would be the right way.

my friend told me that he revved the car in n and then shifted it to d. this was also in a accord v6. dunno how bad that would be for the car. but that was for a burnout.
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Old 20th May 2009, 14:18   #9
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Simple:
2nd option, Hold the brakes down, and slowly accelerate till around 3.7-4K rpm, that's roughly when VTech kicks in, then release the brake at the light, and pedal to the metal baby just take her with a firm hand on the wheel. The accord will win if driven properly!

It's lighter and puts out more power than the 525! Just be careful of launch, I suggest a few trial runs to get acquainted with the car, but it's a no brainer...the Accord all the way.

Make sure you keep the OD engaged though. It'll help hold revs better and hold gears longer thereby increasing power...
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Old 20th May 2009, 14:28   #10
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Winding up the Torque Converter was a popular trick in the US at one time. I do not think it does your fuel economy or the AT any good!
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Old 20th May 2009, 14:36   #11
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my two cents

one should always allow wife (at home), boss (office), customer (work) to win
never fight with them. it is a loss -win or loss-loss situation.

sorry for being off topic
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Old 20th May 2009, 14:37   #12
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Quote:
Torque-ative : Disclaimer:- I condone street racing ...
And we condemn street racing !
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Old 20th May 2009, 16:48   #13
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Quote:
Originally Posted by condor View Post
And we condemn street racing !
Gosh what an over-sight Thanks Condor,..I meant do not Condone !
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Old 20th May 2009, 17:37   #14
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Quote:
Originally Posted by sgiitk View Post
Winding up the Torque Converter was a popular trick in the US at one time. I do not think it does your fuel economy or the AT any good!
I think he put up this query not for fuel economy but for a drag. Besides most AT's on high end saloons can take a little stress once in a while since they are designed to handle higher hp & torques.

Apart from increasing the revs your timing of doing so should be right. Most auto boxes will limit revs while you depress brakes in D. So, if your rev limiter cuts in at, say, 4000rpm, then you ought to also time yourself with the christmas tree. Mistiming your car revs with the red light may cause you to catch the green light when your rev limiter cuts in. That will not do you any good for your launch.
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Old 20th May 2009, 17:52   #15
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switch off the traction control if any. step on the breaks and rev your engine after putting it in D then let go around 4-5k RPM and there you go.
Saw this being done by jeremy clarkson on Top Gear.
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