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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Tracking, Autocrossing, Dragstrip, Driving Techniques > Stock 1/4 mile time at altitude?



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      04-13-2013, 08:02 PM   #1
NEVER ENUF
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Stock 1/4 mile time at altitude?

Just curious what kind of times you all are seeing at altitude. Took mine to Bandimere today (5800 ft with a 6600 DA). Car is a bone stock 08 E92 XI 6MT on run flats. Weighed in full weight quarter tank of gas at 3860 with driver (180lb driver). Here was my best run:

60 ft: 1.920
13.95 @ 97.19 MPH

I wanted to get a baseline before I start modding. What type of times are you all seeing? Thoughts for my time at altitude?
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      04-14-2013, 03:17 PM   #2
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Sounds just right. I also squeaked out a high 13 on my 2008 E90 6MT XI stock at Bandimere last spring. Then I put a Cobb on and ran Stage 1+ with a splash of E85 and no hardware changes and ran a 13.4. I fooled with ATR and lots of E85 last year and ran a 13.1 at 106 but couldn't get my 12 on stock hardware because the stock clutch isn't hooking up on launch now.
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      04-14-2013, 03:26 PM   #3
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Looking at my timeslip my stock data looked like this:

04/07/2012 @ 10:02am, Temperature = 60 degrees, Total weight 4005lbs

60' 1.893
1/8 8.918@77.16
1/4 13.943@98.26

This was on Michelin non-runflat all seasons, spinning a bit on the launch,
traction control off.
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      04-14-2013, 07:30 PM   #4
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Ok, I figured that was about all it had in it at altitude. I was actually surprised to get into the 13's this high up. Thanks for the input.

Now it's time to start putting some parts on and see what it can do. I'm thinking I may need a clutch after I start modding also. Anything in the 2.0 60ft and it was fine, as soon as it was dipping into the 1.9's you could smell the clutch after the run.
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      04-14-2013, 07:36 PM   #5
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You can save the clutch a bit by letting it out as fast as you can and removing the restrictor if necessary to get it to spin the tires instead of slipping the clutch. I do this by flooring it on the first yellow and dropping it on the third yellow which means I've been at full throttle for about exactly one second and am at about 5000rpm which works out about right. But I've now worn mine enough that it's still not enough when the track is sticky. Oh yeah, launch on the outside, out of "the groove" for less traction. But I need a clutch no matter what now. My goal was to hit 13s bone stock here and was pleasantly surprised to do it on the first pass.
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      04-14-2013, 07:37 PM   #6
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I'm hoping Cobb will write some good 2-step code soon. Otherwise I'll be installing a WOTBOX or a JB4 for that functionality eventually. I miss having it from my Mitsubishi.
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      04-14-2013, 08:02 PM   #7
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Yeah, I was leaving the same way to get the best 60fts. Problem is as soon as it was hitting the higher rpm (5k or so) it would hover there for a second before totally hooking up, causing the slip/smell. Anything lower RPM and it was fine but 60 ft suffered. What restrictor are you referring to? First I've heard of it.
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      04-14-2013, 08:07 PM   #8
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I forget what the BMW people call it, but there's a restrictor in the hydraulic clutch system that makes it engage more gently if you drop it hard. Andrew at AR Design in Denver can take it out or replace it with a drilled out factory one if you're trying to maintain stock appearance for warranty reasons or whatever. You can also just do it yourself but there can be issues with getting it bled right and I preferred to just leave it to someone who had done it before.

I went with the drilled out one because I'm still on CPO warranty. I could feel some difference but it wasn't huge. It got me through one more day at the track but then that wasn't enough either. I'm done until I get a clutch.
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      04-14-2013, 09:03 PM   #9
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That time and mph looks pretty much on par at Denver's high altitude.
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