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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Tracking, Autocrossing, Dragstrip, Driving Techniques > launch



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      10-17-2010, 03:06 PM   #1
WDBi
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launch

best way to launch a 335i coupe from a stop and from a roll? its an auto
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      11-30-2010, 08:06 AM   #2
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While trying to answer the same question, I came across this. Can anyone verify?

Process for Engaging Launch Control

1. Turn on Dynamic Traction Control (DTC)

2. Put in "sport" mode (located at gear stick)

3.Enagae "M1" (knock Gear Stick to the Left)

4. Foot on Brake

5. Push accelerator hard (Revs should build up to approx 5000 rpm and a chequered flag should appear on the dash).
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      12-06-2010, 12:23 PM   #3
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is this true i have never heard of a symbol appearing on the dash?
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      12-06-2010, 01:10 PM   #4
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I don't know anything about a checkered flag symbol. And good luck getting the auto up to 5k for a launch.

On the rare occasions I do, I go full DTC on and full DSC off, foot on brake, rev to roughly 2500, launch, and hold on.

Sometimes I will shift it myself, but the DS mode does quite a good job on the shifting, as it should.
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      12-06-2010, 01:11 PM   #5
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BTW, i know we have different cars, 330i/335i, but we share the same transmission and this method works well for me.
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      12-09-2010, 07:52 AM   #6
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Any other ideas?
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      12-09-2010, 02:18 PM   #7
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I'm not sure I would follow anything the guy heard from someone else regarding 5k rpm brake boosts and a "checkered flag" on the dash. (Please school me if I'm stupid.)

Here's my normal 335i launch for drag races:

1. Press the DTC button for 5~ seconds. A little counter-clockwise circular arrow with a triangle in the middle will show on your dash saying DTC is fully OFF. Not on. If you just press the DTC button, only the first DTC light comes on. You have to hold longer for traction control to fully turn off.

Looks like this:

2. Place steptronic in DS mode (knock shifter left). I use DS for 1st gear because it will shift at redline which is pretty much where the shiftpoint for 1st is faster/more accurate than I can. After first, I paddle shift into 2nd and 3rd. I use 6600 rpm into 2nd. Then, 6400 rpm into 3rd. You can definitely feel the car losing power at the higher rpms in higher gears. If you can lift your head, you need to shift is my motto. Keep dropping rpms by 200~ for each gear up if you're going 1/4 mile, etc. That seems to give my stock setup the best times. YMMV.

3. Press your brake in hard with left foot.

4. Hold revs steady at 1500-1800 rpm (100~% torque). I don't feel comfortable doing this longer than 2 seconds. So, do this right before you launch.
Note: Anything above 2k rpm in my opinion is just bad. Go watch the M3 video launching at 4500 rpms. He didn't make it past his second launch. BMW drive axles are pretty damn small and aren't made for traditional clutch dumps in my opinion. 335i autos, I fear, are worse off.
5. Release brake and slowly increase revs to full throttle. You should give the car 2 secs of easing on the power before you full throttle. I seem to spin forever @ full throttle with DTC off. I use full throttle through the rest of the gears. Chirping 2nd is ok I think. 25 ft burnout while an 89 Civic roars down the track is not ok. You'll still catch/beat him but your time will suck.

That's my humble launch. I'm no pro. Always learning something. If someone has a better way, I'm all about using it.

Brent

Last edited by brentseay; 12-09-2010 at 02:26 PM.
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      12-09-2010, 08:41 PM   #8
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thanks thats a great write up will try this next time im at the track
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