[FMOS Racing]

I gave it a stab since the temperature was in the mid 60s yesterday and "only" 37 this morning.

First attempt was the best, still invalid, but 12.5@122 with a 2.2 60'.

Two flubbed attempts after that, then other cars and 3 deer on the shoulder convinced my inner grown-up to reassert himself.

This is the first time I've really hammered on this thing from a stop and tried to nail the shifts. The lack of "no lift shift" in this car is shocking and the dead spot in the acceleration on the shifts is equally as shocking. That has to be a good .2-.3 seconds of "blah" and it feels even worse if I try to powershift (and three gear changes equals almost a full second of "blah"). That characteristic doesn't really show up as glaringly when I'm just whizzing around on the backroads, and I generally like the "shift-surge" feeling. However, when trying to make acceleration runs, it feels a little frustrating.

[captain slowly]

Originally Posted by FMOS Racing

I gave it a stab since the temperature was in the mid 60s yesterday and "only" 37 this morning.

First attempt was the best, still invalid, but 12.5@122 with a 2.2 60'.

Two flubbed attempts after that, then other cars and 3 deer on the shoulder convinced my inner grown-up to reassert himself.

This is the first time I've really hammered on this thing from a stop and tried to nail the shifts. The lack of "no lift shift" in this car is shocking and the dead spot in the acceleration on the shifts is equally as shocking. That has to be a good .2-.3 seconds of "blah" and it feels even worse if I try to powershift (and three gear changes equals almost a full second of "blah"). That characteristic doesn't really show up as glaringly when I'm just whizzing around on the backroads, and I generally like the "shift-surge" feeling. However, when trying to make acceleration runs, it feels a little frustrating.

In all honesty, considering how difficult it is to launch the 6mt in this car quickly, I'd say 2.2 60ft isn't that terrible. I don't see you doing a sub 2 sec 60ft without some really sticky tires and quite abusive clutch dump. Even then, I don't know that you have much more MPH to gain. 122-123mph is moving quite well.

[CSBM5]

Originally Posted by captain slowly

In all honesty, considering how difficult it is to launch the 6mt in this car quickly, I'd say 2.2 60ft isn't that terrible. I don't see you doing a sub 2 sec 60ft without some really sticky tires and quite abusive clutch dump. Even then, I don't know that you have much more MPH to gain. 122-123mph is moving quite well.

Yeah, the 60' time will not materially effect the trap speed. Heck, it's not uncommon to lose a tad on trap with a slightly faster 60' time. Trap speed is such a great measure of power/weight ratio while the 60' is really a measure of grip (and driveline stress!). A stock M2C traps 114-116 range, so 122 is getting it pretty good. The CS traps ~120.

[FMOS Racing]

Yeah, I agree, it was a fairly clean run - and actually surprised me at how well it dug with a little clutch slip. I was full in it by halfway through 1st gear. I figured I'm at that point where I can improve the ET a bit, but probably not much more in the way of MPH (it was 122.8). Shifting was a little sloppy on that attempt, but I wasn't disappointed in it overall. I tried to be a lot sharper on the next two attempts, but that torque cut and the CDV behavior on the 1-2 shift were killjoys.

I may try to game it with a couple of gallons of E85 or some Torco (currently on 93 octane) and some weight reduction just so I can try for 125+. And do keep in mind that my car does have a cat back exhaust on it. I don't know if that makes any difference at all, but it's not "tune only" whatever the case.

[FMOS Racing]

That "blah" spot is so bad that the car actually slows down on the 2-3 and 3-4 shifts...

[FMOS Racing]

I'm an engineer, so I love digging around in information. As an interesting (to me) visual experiment, I overlaid my pass with the one that MSH_ posted earlier in the thread. The compressed X-axis in the overlay is an adjustment I made for the different time scales (11.5x vs 12.5x).

I've never been one to accept the MT vs AT/DCT acceleration favoring the AT because of the way I shift, but in this car, the difference is extremely obvious.

[chris719]

Originally Posted by FMOS Racing

I'm an engineer, so I love digging around in information. As an interesting (to me) visual experiment, I overlaid my pass with the one that MSH_ posted earlier in the thread. The compressed X-axis in the overlay is an adjustment I made for the different time scales (11.5x vs 12.5x).

I've never been one to accept the MT vs AT/DCT acceleration favoring the AT because of the way I shift, but in this car, the difference is extremely obvious.

Attachment 3392833

These gearboxes just do not like to be rushed into 2nd or even 3rd really. My Z4M was even worse into 2nd but you could really shift quickly into 3rd without abusing it. All the magazine times for these BMW 6MTs are crazy because no one would slam the shifter into 2nd like C&D does on a press car.

[captain slowly]

had my 3rd service today, which includes spark plugs. My car has pretty much 20000 miles on the dot and has been tuned for roughly 8000 miles. I'm being told (didn't get them back to verify) that they were well worn, and the car feels much more responsive now. Could be the placebo effect, but maybe not. So going forward, I plan on doing plugs every 20k max. I suggest you do too.

[cwunch]

Originally Posted by captain slowly

had my 3rd service today, which includes spark plugs. My car has pretty much 20000 miles on the dot and has been tuned for roughly 8000 miles. I'm being told (didn't get them back to verify) that they were well worn, and the car feels much more responsive now. Could be the placebo effect, but maybe not. So going forward, I plan on doing plugs every 20k max. I suggest you do too.

I have seen broken plug tips on 31.000miles. On low powered Turbo BMW’s, it is suggested to change spark plugs every 22.5k miles or every 3rd oil change.

For s55, 20k miles is ok. If it is remapped, you can even consider changing every 17.5k.