BetterMakeWay

Sorry but i'm not in the position to comment about smg drag racing or launching in the best possible way using a smg. My experience with smg is very limited. I do know one thing though, that whenever i drag raced from stand still with my steptronic, i got excelent results by brake torqing and in the same time having the traction control in DTC form. From what i experienced and observed it happened smth like this: i've selected M1, selected then DTC, left foot hard on the brake, right foot begin to apply throttle and the engine revved till somewhere around 2000-2500rpms (considering i have a diesel, a petrol might rev even higher); rpm level at wich the needle froze...not going over that value even tohugh i had my foot planted into the throttle. At first i thought that was some kind of gearbox security...but the guys that watched the drag said that a few seconds before the actualt start, the rear tires became to spinn a little, made out some smoke and then i went off instantly when i took the left foot off the brake. That imo is a good start. After many other experiences at dragging i found that if you disengage DSC completly, you do get tire spin, ALOT (when you brake torque), you may even consider it a burnout, but that might not be the best way to launch since it will keep spinning way after you took the foor off the brake. The conclusion was this: i realised that the gearbox doesn't have any security feature that blocked me from building revs in the case when the DTC was activated, but exactly the DTC was the one that did exactly that. By wheelspining a bit it sensed wheel spin and restricted my revs electronicly so the car acted almost like having a proper launch control. I dunno how much power i lost after the car got launched, by having that dtc enabled but i can assure you that it felt very solid, without feeling like the engine was restrained in any way. I won both races, and big time, but hey 1st run was a honda civic type r 2006 model and the 2nd a golf v gti with some little mods (air filter and exhaust). In the 2nd run when dsc was 100% off there was resonable wheel spin but also the car felt quick so i cannot really tell wich mode is best because i didn't have the chance to properly test both types of launches with precise measurement toys. I might take a guess that the DTC mode is a little bit quicker since there is a considerable lost time from all that wheel spin in the 2nd mode. Too much wheel spin imo. Also i have 245 on the back so that imo is a disadvantage. I reckon that when i'll have 275 on the back i would get even better performance because of the higher level of grip. Anyway it's quite hard to have a good launch with DSC completly off...1 because if you don't brake torque and just floor the throttle you'll loose time by loosing grip, but if you lighten up the throttle you'll find more grip but less hp used so again lost time and 2nd if you use brake torque (wich imo is a must for a good launch) you'll have to be carefull and keep an eye on the revs when you'll better lift off the brake. For me it works best around 2000rpm 2500 tops when engine reaches peak torque.
Pfewwww i'm tired.... Sorry i couldn't be more of assistance on the smg problem. A friend of mine once showed me when he used LC on his e46 m3, keeping the - pedal depressed and also the brake but i forgot the whole process.

jet190rs

LC (actually called "Acceleration Assist" on the non-M5 E60s with SMG) can only be activated with both DSC and DTS off. It'd be interesting to see if it indeed assists acceleration time Have any members here timed a 0-60 run using SMG's AA?

znod

Wow, thanks for all the info. When I want a quick start (these days) with my Step, I do mild, hopefully non-abusive, brake torquing and turn both DSC and DTC off. These days I rarely get too much wheel spin. Before 20.01.00, I used to get way excessive wheel spin without brake torquing at all.

znod

Thanks for the reminder/clarification about AA. The only person I know of that has tested an SMG 545i using a g-meter is Realtyman. I think his best was 5.32 to 60 MPH. I don't recall if he used AA on this best run. The best post 20.01.00 Step-545i times generated using meters, to my knowledge are, are given below.

grogan545i (Steptronic):

1/8 Speed--80.473
1/8 time--8.650
0 to 60--4.89

The above values are unadjusted for altitude (534') and weather (26F; Dew Point--5 F; Pressure 30.18). To my knowledge, reliable formulas are not available for making such adjustments for anything but 1/4 mile data.

Znod (Steptronic):

Unadjusted for Altitude and Weather:

1/4 Speed--102.71
1/8 Speed--82.45
1/4 Time--13.629
1/8 Time--8.853 (Before 20.01.00, I had 3 8.71's without adjustment and with 55-60F and 1550' altitude)
0 to 60--5.149

Adjusted for altitude (1550') and weather (49F; Dew Point--21 F; Pressure 30) are:

1/4 Speed--104.83
1/4 Time--13.451

Bokke has been learning to drag race his manual 545i and has been doing some related testing. To date, his unadjusted (of course) bests are:

1/8 Speed--77.2
1/8 Time--9.17
0 to 60--5.51 (see CD 5/04 below)

All I know about his altitude and weather are: "Temp:40F; Hum: 27%.")

I posted the following above, but am doing so again for direct comparison. Note that CD adjusts only for weather (pretty low altitude though--usually Michigan) and uses a 3 MPH rollout. In this regard, we all use a 1' rollout. RT uses aggressive, yet not abusive, test procedures, a 1' rollout, and makes no altitude/temperature adjustments. None of us use abusive procedures. MT also adjusts only for weather and uses a 1' roll out.

BMW 545i--Manual CD 5/04 5.5 14.1 102.8
BMW 545i--Steptronic RT 6/05 3814 5.2 13.7 104.0
BMW 545i--Steptronic MT 8/04 5.4 13.7 102.1
BMW 545i--Steptronic MT11/05 5.5 13.8 102.8

BetterMakeWay

Can you please enlighten me on the rims question?

znod

Me? Sorry, I didn't see a rims question, but please ask again if your post was meant for me.

Bokke

Znod - thanks for being kind....the driver and the car are learning

znod

You are welcome, but note that you, for all practical purposes, tied the mag I referred to on zero to 60.

EBMCS03

No way theres not "all the advantages" theres like one... straight line acceleration and thats it, and thats a maybe... Actually to be honest I think if you use Acceleration Assist on the SMG you can bet a better time than the Steptronics but i wouldnt want to beat on the clutch at every stop light... like how you can on a step...

Why the SMG? Cuz you get much better control especially on twisties and in turns. I think the shifts are faster and better even in regular driving mode than the step, it doesnt always upshift to the highest gear, you get crisps shifts with SMG, none of this sloppy lazy shifts that the steptronic does... Its personal preference... I much prefer the manual feeling of a shift with SMG.

With the steptronic even if you slap it over in manual mode the shifts are still not crisps... theres still the torque converter lag/feeling...

swajames

Thanks, I did, I appreciated the reply.