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      05-20-2012, 02:37 PM   #1
shiv@vishnu
Tuner
 
Drives: X1, 335i
Join Date: Sep 2006
Location: SF Bay, CA

Posts: 17,616
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Exclamation Vishnu Tech: 10s 1/4 run VBOX data analysis

Hi guys-- Sean and I just left LA. Only 360 miles to go before we are back in the Bay area. The 335 is a champ. I don't think there are many other platforms in this price range that we would be comfortable doing this with (driving 1000 and running 10s, all within 36hrs with no support car/crew). And the car just past 90k miles during this trip!

Finally getting a chance to look at the vbox data from the 1/4 mile pass. Some interesting data. Can't post graphs from the road so I'll post them when I get back to the office tomorrow.

Peak/sustained acceleration G:
1st gear: 1.3/1.15
2nd gear: 0.87/0.82
3rd gear: 0.61/0.60
4th gear: 0.55/0.34

Shift time (deccel duration between gears)
1-2. 0.38s
2-3. 0.41s
3-4. 0.38s

Trap speed: 132mph
WHP Calculator results using 3500lb vehicle weight (with driver) and theoretically "perfect" driving in ideal conditions.


http://www.race-cars.net/calculators...lculator.html: 628whp
http://www.dragsource.com/index.php?...&calctoview=5: 629whp
http://www.fbody.com/calc.htm: 628whp

We have attempted to dyno the car with slicks before to verify but they end up turning to mush and sliding around on the rollers. A good testimate on how much power they are absorbing is 20-25whp due to tire tread distortion (from being an under-inflated bias ply). But they certainly more than make up for it with traction benefits (1.5x 60' time!). I thought the HP calculator results were interesting because one of our competitors is trying to suggest that the car is underperforming at the track based upon published dyno results. Sometimes I really question the motivation of others who have nothing to gain by spreading misinformation. As well as that of some of their customers do buy into their disingenuous nonsense.

Some more data crunching also suggests that we should be able to shave at least 0.05-0.07s off of every shift based upon other runs (on precious days). So I'm quite confident that the car has a mid to high 10.6 in it with just faster shifting. And another .05-0.1s in the launch (the car bogged slightly in the run). So we are projecting low 10.6s when all is said and done in these relatively warm conditions in a "perfect" run (if such a thing even exists). Once we reach that or something close to it, we will starting bumping up power again

Again, thanks to all those who have supported and encouraged us along the way

Last edited by shiv@vishnu; 05-20-2012 at 03:16 PM.
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