[GT500R]

Hey guys,

So something that I never found was what is the real difference in acceleration between launch control and just plain hitting the gas from a start.

A lot of hear say and this, but how much of a difference is it really?

Well, I found out...

2018 X3 M40i - Stock - 8,760 miles
19'' Rims w/ All Season Run Flats
93 octane (full tank)
Temp = 61*
DA ~ +85 ft

All runs were in Sport+ and traction control off.

First 2 runs I did not use launch control, just straight hit the gas.
Next 2 runs I did, used launch control to 2100 RPM
Last run (#5) I did not use launch control, just hit the gas for a consistency check.

Results below -



1. Launch control takes off around .4 seconds or so
2. In terms of car lengths, if two X3 M40i's are racing the one using launch control will be approx. 3/4 of a car ahead of the one not using launch control.
3. We found our answer

Launch Control -

No Launch Control -

Thanks guys, up next will be BMS intake 0-60 before and after results.

[pskdude]

Very! informative post! Thanks! would love to see the BMS intake install, seems like without boosting there is a loss in torque from what I understand.

[Seaz]

Your letting off the brake too quick, you need to let it settle in at 3000rpm

Youll notice it slows at 2000 but will keep building to 3k

[Njerts]

Nice!
I would love to see the difference between sport, sport+ and comfort by just flooring it 0-60

[j1980mac]

Originally Posted by Seaz

Your letting off the brake too quick, you need to let it settle in at 3000rpm

Youll notice it slows at 2000 but will keep building to 3k

Would the difference from letting it build (2000-3000 rpm) adversely affect the torque converter or turbo at all?

[Seaz]

Originally Posted by j1980mac

Would the difference from letting it build (2000-3000 rpm) adversely affect the torque converter or turbo at all?

Launch Control was built to go up to a preset max of 3000rpm, its what its built for.

[ParadigmDawg]

Shocker....building up boost before you take off makes a car faster.....Who would have guessed...lol...

You need to stay on LC longer, you weren't at 3,000 rpm so not at full launch boost.

[GT500R]

Originally Posted by pskdude

Very! informative post! Thanks! would love to see the BMS intake install, seems like without boosting there is a loss in torque from what I understand.

Thanks !

Originally Posted by Seaz

Your letting off the brake too quick, you need to let it settle in at 3000rpm

Youll notice it slows at 2000 but will keep building to 3k

I have not ever seen it go to 3K, even when sitting for a couple of seconds. Other videos online don't show 3K either from a stop, maybe 2,500 or 2,600 but not 3K.

Have a vid? And not JB tuned?

[j1980mac]

Originally Posted by Seaz

Launch Control was built to go up to a preset max of 3000rpm, its what its built for.

Well then... I like it. That settles that.

[DigiSage]

I’ve LC’d a bunch of times now and the RPM it eventually settles at seems to be different every launch. Sometimes it’ll get to 2900 or so and other times only to 2400.

[GT500R]

Originally Posted by ParadigmDawg

Shocker....building up boost before you take of makes a car faster.....Who would have guessed...lol...

True, but it wasn't which is faster, its how much faster if you re-read

[GT500R]

Update: held launch control for 5 seconds and could get a max of 2700

[sinbad4]

I'd like to know from start using manual Sport+. That is pretty much all setting for launch control - stabilization off, sport+ mode, brake on, hammer throttle then release brake, just like when using Launch Control, only in M mode and shifting by paddle. I tried this today and liked it better than launch control.. though wondered about my time vs. full LC.

[808ron]

For those who say you can’t get to 3k rpm have you tried using the cruise control toggle to up the desired RPM? I haven’t tried it yet but you can up or down tick the rpm between 3-3.5.

[DigiSage]

“Cruise control toggle”? Can you please explain this process in much greater detail?

[Neo1130]

Originally Posted by DigiSage

“Cruise control toggle”? Can you please explain this process in much greater detail?

I did a quick search and could only find this for true M cars. Not the M40i's...

[808ron]

It was here.

https://www.bmwblog.com/2017/12/02/v...nch-bmw-m-car/

Could be only true M. I haven’t tried it yet.

[GT500R]

There is a difference between the DCT and the traditional ZF with torque converter.

I tried the cruise control trick and didn't see any difference in RPM... anyone else try it?

[ND40oz]

Originally Posted by GT500R

There is a difference between the DCT and the traditional ZF with torque converter.

I tried the cruise control trick and didn't see any difference in RPM... anyone else try it?

Yeah, with the automatic you're going to be limited by the torque converter stall speed most likely, unlike what it's doing with the DCT and engaging the clutch at your dialed in rpm.

Need someone to test on an X5M or X6M to see how it behaves or the new M5 which is running the ZF8 as well.

[ParadigmDawg]

Mine hits 3,000 no problem on my tune.

[GT500R]

Originally Posted by ParadigmDawg

Mine hits 3,000 no problem on my tune.

This definitely has something to do with JB4 I would assume and how it alters the boost/sensors. Although do you see the same with stock airbox?

[ND40oz]

Originally Posted by GT500R

This definitely has something to do with JB4 I would assume and how it alters the boost/sensors. Although do you see the same with stock airbox?

The torque converters stall speed will be higher because of the additional torque due to the tune. Its holding capacity hasn't changed so if you add more torque, rpms go up until you add too much and you get slippage.