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      07-08-2008, 12:54 PM   #1
icemang17
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Launch control hits rev limiter???

So I finally passed break in and wanted to try launch mode.....it works sweet...but both times I tried it, it hit the rev limiter just briefly in 1st gear...followed by a BRUTAL shift to 2nd (in a good way)..... I'm sure it hurt my times a smidge by banging the limiter....but the times weren't as good as I thought.....granted the traction was marginal at best.....which I figured out trying a launch in S5 with the DSC off....it was parked for quite a while just smoking the tires (fun but not fast)....

My best runs were

0-60 4.47
0-1/4 12.82 @ 114.10 mph

Not as quick as I was hoping for.....but with better traction I'm sure times will improve....everything was timed by my ancient Gtech Pro...

I did try an M mode with MDM and D5.....far slower at:

0-60 4.87
0-1/4 13.38 @ 112.90 mph

Generally my Gtech runs a tenth of two slower than the drag strip reads..... & I'm going to the drags tomorrow...but its going to be brutally hot so the times probably won't improve that much....
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      07-08-2008, 01:22 PM   #2
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Any issues getting yout Gtech to measure and calibrate the engine rpm? Mine would not get a reliable rpm calibration at all. Tried repeatedly.
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      07-08-2008, 01:26 PM   #3
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one hand... you are killing your car...
on the other... sounds like a lot of fun

you tried with lc and s5/d5 ?

your post sounds like lc shifts in 2nd gear automated, is this correct?

have you some s6 /s5 comparison times?

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      07-08-2008, 01:36 PM   #4
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Quote:
Originally Posted by icemang17 View Post
So I finally passed break in and wanted to try launch mode.....it works sweet...but both times I tried it, it hit the rev limiter just briefly in 1st gear...followed by a BRUTAL shift to 2nd (in a good way)..... I'm sure it hurt my times a smidge by banging the limiter....but the times weren't as good as I thought.....granted the traction was marginal at best.....which I figured out trying a launch in S5 with the DSC off....it was parked for quite a while just smoking the tires (fun but not fast)....

My best runs were

0-60 4.47
0-1/4 12.82 @ 114.10 mph

Not as quick as I was hoping for.....but with better traction I'm sure times will improve....everything was timed by my ancient Gtech Pro...

I did try an M mode with MDM and D5.....far slower at:

0-60 4.87
0-1/4 13.38 @ 112.90 mph

Generally my Gtech runs a tenth of two slower than the drag strip reads..... & I'm going to the drags tomorrow...but its going to be brutally hot so the times probably won't improve that much....
It sounds like you know what you're doing, however are you sure you hit the limiter, because on the LC start the 1-2 shift seems longer than expected with a slight pause in acceleration on the shift. Were the tires still spinning in first on the 1-2 shift?

You don't happen to own a video camera mount so you can share your dragstrip experience, do you? I'd love to see that.

Your first numbers of 4.5ish is about the same I got when clocked manually from reviewing my video'd LC start.

Quote:
Originally Posted by Hammer View Post
your post sounds like lc shifts in 2nd gear automated, is this correct?
All shifts in LC mode are automated. Automated shifts end as soon as you lift off the throttle, thus exiting LC mode.
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      07-08-2008, 01:43 PM   #5
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Unfortunately I do not have a video camera..... :>(

I did several comparison runs.....when using launch control if you have the car in "M" mode LC will not work...... you have to follow the instructions perfectly....

Stop car with foot on brake
turn off DSC
select S mode & put to 6
push shift forward and hold
checkered flag shows up on center screen
left off brake and floor it....
RPM to 5500 (I did not try adjusting it)
let go of the shifter and your GONE.....

In M mode using MDM and S5 my times were good, but consistently slower than using LC...the one time I tried using M mode, S5 and DSC "off" resulted in a sweet burnout...but the slowest times I recorded all day....

However at the strip where the traction is far better....DSC off might be far better.... I will use LC at the strip and plan on launching higher than 5500...hopefully 6000 if the traction is good...which it may not be due to the extreme heat that is forecasted (107F)

I'm going to the Sacramento drags Wed night...a friend with a C6 Z06 is also going....
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      07-08-2008, 01:58 PM   #6
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Quote:
Originally Posted by icemang17 View Post
...
In M mode using MDM and S5 my times were good, but consistently slower than using LC...the one time I tried using M mode, S5 and DSC "off" resulted in a sweet burnout...but the slowest times I recorded all day....

However at the strip where the traction is far better....DSC off might be far better.... I will use LC at the strip and plan on launching higher than 5500...hopefully 6000 if the traction is good...which it may not be due to the extreme heat that is forecasted (107F)

I'm going to the Sacramento drags Wed night...a friend with a C6 Z06 is also going....
did you compared s5 and s6? i guess s6 > s5, but there is no DSC to help... skillbased?
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      07-08-2008, 02:01 PM   #7
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How do you know you are hitting the rev limiter?
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      07-08-2008, 02:16 PM   #8
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Your times are about what I would expect... if you think your Gtech is about a tenth slow then you are running just under 4.4 seconds 0-60 which is great considering you should, in theory, be able to repeat this time all day long over and over again. Something a 6MT will not be capable of.

On the other hand my experiences with G-tech have been mixed. I realize their newer versions are really quite good and I hope they take into consideration the grade of the road as that has produced skewed results in the past for me on older generations of the G-tech.

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      07-10-2008, 12:19 PM   #9
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I might order a newer G tech to see how it is.....I also plan to go to the local drag strip next week when the weather is better to get some official times
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      07-10-2008, 10:05 PM   #10
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I did a launch control launch today. I got more wheel spin than previous and it also hit the limiter on the 1-2 shift. I also got a lot more wheel spin in second. I suspect if I had adjusted the launch rpm down a bit it might not have hit the limiter, but that's just spectulation.
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Last edited by skierman64; 07-12-2008 at 09:56 AM.
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      07-11-2008, 10:09 AM   #11
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great fun..

this is why I don't buy used cars however.
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      07-11-2008, 11:04 AM   #12
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Quote:
Originally Posted by skierman64 View Post
I did a launch control launch today. I got more wheel spin than previous and it also hit the limiter on the 1-2 shift. I also got a lot more wheels spin in second. I suspect if I had adjusted the launch rpm down a bit it might not have hit the limiter, but that's just spectulation.
Interesting....so I'm not the only one..... I thought the 100 octane gas I put in might have caused the engine to rev a bit quicker...but I doubt it....

Were you using standard crappy 91 octane?
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      07-12-2008, 10:02 AM   #13
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Quote:
Originally Posted by icemang17 View Post
Interesting....so I'm not the only one..... I thought the 100 octane gas I put in might have caused the engine to rev a bit quicker...but I doubt it....

Were you using standard crappy 91 octane?
It was 93 octane, but increasing octane doesn't give the car more power without increasing the compression.

I've done about 6 launch control launches and this most recent one was the first one where I hit the rev limiter. I also got a lot more wheel spin than previous attempts. I think, the wheel spin correlates to hitting the limiter. Lowering the launch rpm should prevent hitting the limiter.
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      07-12-2008, 10:16 AM   #14
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Quote:
Originally Posted by skierman64 View Post
It was 93 octane, but increasing octane doesn't give the car more power without increasing the compression.

I've done about 6 launch control launches and this last one was the first one where I hit the rev limiter. I also got a lot more wheel spin than previous attempts. I think, the wheel spin correlates to hitting the limiter. Lowering the launch rpm should prevent hitting the limiter.
The reason I put in 100 was to increase the average octane...since 91 is the minimum and ideally the engine needs at least 93 for optimum performance... The average octane of the whole tank was 98...

Interesting point about wheelspin causing LC to hit the limiter....since I got quite a bit of wheelspin everytime due to the fairly low traction (think low traffic) roads I tested it on.....I'll have to try it on a better road surface...
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      07-12-2008, 09:08 PM   #15
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I tried launch control for the first time today and left about a 15 foot burnout. A ton more wheel spin and fish tailing than I expected.
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      07-12-2008, 10:38 PM   #16
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Quote:
Originally Posted by darkalley View Post
I tried launch control for the first time today and left about a 15 foot burnout. A ton more wheel spin and fish tailing than I expected.
Sounds like fun....
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      07-13-2008, 02:59 AM   #17
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Quote:
Originally Posted by icemang17 View Post
I might order a newer G tech to see how it is.....I also plan to go to the local drag strip next week when the weather is better to get some official times
I have an older G-Tech unit and I was able to download the newer version firmware from their website. After that my G-Tech ran exactly like the new ones. You might give it a try unless you have the very old, original G-Tech.

I found with my E46 M3 SMG, the G-Tech would not read as the launch was so brutal at 2K with LC running pilot sport cup tires with lots of traction. I got 4.7 0-60 and 13.2 @ 108. The E92 M3 is definitely faster.

Go easy on the LC....I'm guessing BMW software is counting the number of times you use it and will use it against you if you burn up the clutches. Sounds like lots of fun...let us know how the drag strip goes.
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      07-13-2008, 03:00 PM   #18
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Quote:
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I have an older G-Tech unit and I was able to download the newer version firmware from their website. After that my G-Tech ran exactly like the new ones. You might give it a try unless you have the very old, original G-Tech.

I found with my E46 M3 SMG, the G-Tech would not read as the launch was so brutal at 2K with LC running pilot sport cup tires with lots of traction. I got 4.7 0-60 and 13.2 @ 108. The E92 M3 is definitely faster.

Go easy on the LC....I'm guessing BMW software is counting the number of times you use it and will use it against you if you burn up the clutches. Sounds like lots of fun...let us know how the drag strip goes.
With such a powerful computer running everything I figure its possible that BMW can record just about everything you do with the car for later downloads....then with GPS it can know the exact date, time & place you did LC or exceeded some rpm or speed threshold they setup?
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      07-13-2008, 03:21 PM   #19
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I really doubt they are keeping track of much. On the E46 M3 they could only tell how much time (minutes) the car was above redline, as in a missed shift causing the over rev. I'm guessing the new M3 is about the same. If they offer LC, then people should be able to use it as much as they want. It won't allow back to back LC without a cooldown in between.

Keep us posted on your actual dragstrip times.
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      07-13-2008, 08:22 PM   #20
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Quote:
Originally Posted by icemang17 View Post
With such a powerful computer running everything I figure its possible that BMW can record just about everything you do with the car for later downloads....then with GPS it can know the exact date, time & place you did LC or exceeded some rpm or speed threshold they setup?
I'm sure they could track all that if they wanted, but it would also lead to liability issues as cops would get a warrant for the information stored by the car and use it in court against the owners. GM cars store pre accident information and it's been used against owners on multiple occasions. BMW has stated that they won't design the cars software to store that type of information. I'm basing this info on a Car and Driver article a read a few years back.
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