[Max Well]

Having evaluated the performance of the F25 X3 in threads 'HP and Speed - the graph' [ http://x3.xbimmers.com/forums/showthread.php?t=1004702 ] and '!X3 Acceleration Files - Master List!' [ http://x3.xbimmers.com/forums/showthread.php?t=1149189 ], it seemed reasonable to begin a F25 1/4 Mile Thread much as our colleagues on the F30 forum did back in Oct 2012. In three years it has garnered roughly 33K views, and although that model may attract more folks interested in modifications and maximizing performance of their vehicles, it seems there is a segment of our X3 realm which shares similar interests. Also, this will allow the Acceleration thread to remain as a reference for the methodology while (whilst) still allowing a centralized repository for performance data provided by formal drag slips.

The following templates are being attached: Chart Worksheet for making notes at the track; overview graph of the 0-16 sec plot of the 28i performance curves ranging from stock HP +/- 50 HP in 10 HP increments (including the boxes showing the zoomed regions); graph of 8-10 sec performance curves which captures the 660 ft (1/8 mile) point; graph of 13-15 sec performance curves which captures 1320 ft (1/4 mile) point; and the 60 mph interval which can provide an extrapolation of one's 0-60 mph time once the reference curve from the 1/8 and 1/4 mile times has been established. These should make it easy to plot in real-time while at the track and in-between runs. Note these curves have been run at sea level for continuity. References suggest up to 1200 feet altitude doesn’t have a major effect on the performance of turbocharged engines, which may be why correction factors below this altitude aren’t common. http://wallaceracing.com/altitudecorrection.htm

As an example of how the worksheet can be used, I am including a summary of ROBNYC's, mge92's, and Crashnbrn5's runs at Island Dragway and also providing the 'split times', which allow a more detailed look at performance as it removes rollout differences, (a summary of their usefulness can be found at http://www.motorsportsvillage.com/timeslip.html ). Note Excel has highlighted the fastest runs for each person's specific interval to make it easier to gauge the effects of tuning adjustments. If actual drag slips can be posted as jpegs, then periodic summary tables can be made. Also, if feasible, if tunes can be disabled briefly to allow stock run data to be obtained on the days modified runs are to be made, that should enable a reasonable reference with which to compare differences due to actual performance changes vs the host of other variables which can change between days and influence the end result (temp, barometric pressure, altitude, weight, tires, track ...).

As mentioned in the other threads, these equations and graphs are simply meant to provide those of us without dynos and high-end software to be able to at least put some science behind the performance of our vehicles. Thanks for reading, and if interest is there, curves for the 35i can also be produced.

[Max Well]

For Howie Dub and others with the 35i. If anyone has any old drag slips of their 35i runs and wish to share to add to Crashnbrn's data, feel free to post some jpegs.

[Max Well]

Rob provided jpegs of the drag slips in a PM so their data has now been entered into Excel. Although I plan on keeping each member's spreadsheet as a running chart, because of size constraints I'll just share their previous run for comparison if the width becomes too large. As before, purple shading in the interval times indicates the fastest time of the row.

[FSociety]

Crashnbrn5 mge92