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      03-24-2019, 05:39 PM   #1
dr.roro
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First time at the dragstrip -- how's my 1/4 mile?

2015 F32 435i M Sport
N55 EWG / RWD / 8AT / DHP
OEM 19" 437M Forged Wheels
Michelin Pilot Super Sport (245/35/19, 265/35/19)
BP 93 octane (~2/3 full)

58-62F Sunny
21% RH
Elevation 118'

Had a great first day at the dragstrip today at Capitol Raceway in Maryland. I wanted to get some baseline runs before tuning this summer, as well as get some drag experience under my belt. Since it was my first time, I skipped the burnouts for the first 3 runs and tried using Launch Control. I kept slipping and bogging like crazy!! ETs were in the 14's and I was getting frustrated.

So then I changed up my technique. I dropped the rear tire pressure to 31 psi (fronts were kept inflated at 38), did a very quick burnout before staging just to get all the gravel and rocks off the tires, and tried brake torquing myself (to around 2000 rpm after staging). Kept it in Sport+ and shifter in S mode. I didn't care too much about reaction times since I was just doing test and tune. This was much better! I'm quite disappointed in the launch control, but maybe it was just getting a few runs in, maybe it was the quick burnouts, maybe it was the tire pressure, but the next 3 runs were much better in the low-mid 13s. Not too bad considering I see published times higher than that, and I'm still stock other than the wheels/tires (OEM M2 setup).

Here's my last and best run of the day (I'm on the left):
13.270 @ 106.34 mph



How's this look? What can I do to improve my launch and 60' time? I couldn't seem to be able to break under 2.0.

Last edited by dr.roro; 03-25-2019 at 05:36 PM..
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      03-25-2019, 06:36 PM   #2
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Really not too bad tbh

The thing with the run flats is even if you lower the tire pressure youre not really getting anything by doing it as they are meant to hold their shape even with no air for x amount of miles before they break down.

So from my experience (20 years or so) of high hp drag racing, tuning etc etc... with street tires, pull around the water box as to not get your front tires wet and drag water up to the staging lines. do a quick spin of the rear tires to clean them off and to get them warm and then stop. Doing big smokey burns outs will do a few things with street tires... waste rubber and if you get them too hot they will become "greasy" and slick.

Its very difficult to get sub 2.0 60' times with any street tire on most cars. the trick with launch control on these cars seems to be to not sit for any long period of time with it engaged. You need to engage it and go, so timing is key. Also, yes..you have no reason to worry about reaction time as it does not effect you times in anyway. You can sit there for 45 seconds and still run a 13.0 etc
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      03-25-2019, 09:20 PM   #3
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Phantom10R Thanks for the feedback! Just for clarification, these are MPSS non-runflat tires. I'll definitely try backing into the water box next time. What do you think about the tire pressures? Should I go lower on the rears? Should I try DSC off instead of Sport+? Manual paddle shifting at a specific RPM? Or do you think I'm pretty close to the limit given the current specs?
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      03-26-2019, 10:10 AM   #4
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Quote:
Originally Posted by dr.roro View Post
Phantom10R Thanks for the feedback! Just for clarification, these are MPSS non-runflat tires. I'll definitely try backing into the water box next time. What do you think about the tire pressures? Should I go lower on the rears? Should I try DSC off instead of Sport+? Manual paddle shifting at a specific RPM? Or do you think I'm pretty close to the limit given the current specs?
Still, I wouldnt lower the pressures too much. Lowering pressure is to add sidewall flex. most street tires dont have much flex. you really want whatever pressure gives you the most contact patch. I wouldnt drop the pressure more than a few pounds.

As far as manual and shift points etc.. that will very. With my car I didnt see any gains really over letting the car shift itself in sport mode. Thats a trial and error type of thing unfortunately.
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      05-23-2019, 02:17 AM   #5
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Try launching in second gear with this:

https://burgertuning.com/products/bms-downshift-blocker
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      05-23-2019, 08:48 AM   #6
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Quote:
Originally Posted by B58 View Post
Try launching in second gear with this:

https://burgertuning.com/products/bms-downshift-blocker
I'll try that next time, especially now that I'm BM3 Stage 2.
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      05-23-2019, 10:21 PM   #7
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Quote:
Originally Posted by dr.roro View Post
I'll try that next time, especially now that I'm BM3 Stage 2.
The car doesn't feel as "fast" because of the pedal kick down being eliminated, but if you look at your logs your throttle and pedal are both reading 100 so it actually works great. I don't use the kick down eliminator anymore because i learned where to keep the pedal when i launch in second gear just takes a bit of practice.
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