[Max Well]

Originally Posted by X4guy

Thanks for the work Max, much appreciated.

Originally Posted by Max Well

Thank you for the kind words, X4guy - I'm happy to be able to share data on these amazing BMWs. If you think any of the X4 folks would be interested in dedicated curves for your line I'd be pleased to prepare those as well for you.

Originally Posted by X4guy

That would be most welcome if it's not too much trouble.

Having evaluated the performance of the F26 X4 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 F26 X4 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 are segments of the X3 and X4 realms which share similar interests. This will allow for a reference base 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 included a summary of ROBNYC's, mge92's, and Crashnbrn5's F25 X3 runs at Island Dragway in the ‘F25 X3 ¼ Mile Thread’ I wrote 2 days ago [ http://x3.xbimmers.com/forums/showthread.php?t=1176284 ]. Note it also provided 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 ). I had Excel highlight 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, wind, 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]

X4 40i Qtr Mile -

[FSociety]

Me and mge92 have more updates from last week drag-racing during the day time under the sun

[Max Well]

I just learned of your X4 40i order, Rob - congratulations!

Hopefully it won't be long before we start seeing some of your drag slips to see how it performs at your strip. This should be a lot of fun for you even before you perform any enhancements, and it'll be interesting to see how close the simulation's projections are to your real world numbers.

[Max Well]

As jtd posted a video produced by /AutoTopNL, entitled 'BMW X4 M40i van Laarhoven BMW, Acceleration' two days ago [ http://x3.xbimmers.com/forums/showthread.php?t=1229978 ], in which the film shows simultaneous time and the instrument cluster, it became possible to extract some data points.

As the chart attached shows, these were chosen randomly across that vehicle's acceleration time, and then graphed against the Simulation's hypothetical curve attached some time ago.

As expected the sim has difficulty modelling the first few seconds take-off as so many traction variables are at play, but by 3.2 sec it tracks the real data quite closely and the curves essentially sumperimpose. By 26 seconds the real X4 begins to show higher than expected speeds and ends with a top speed 6.4 km/h higher than the sim predicted (260 km/h [161.6 MPH] vs the sim 253.4 km/h [157.5 MPH]). As the video does not identify the track course, the differences in road grade along the way, wind speed or direction, or elevation, it is difficult to make any conclusions on the high end difference, but it seems possible one (or more) of those variables could be influencing that result.

Rob will undoubtedly provide 1/4 mile data once his arrives.

[FSociety]

Originally Posted by Max Well

As jtd posted a video produced by /AutoTopNL, entitled 'BMW X4 M40i van Laarhoven BMW, Acceleration' two days ago [ http://x3.xbimmers.com/forums/showthread.php?t=1229978 ], in which the film shows simultaneous time and the instrument cluster, it became possible to extract some data points.

As the chart attached shows, these were chosen randomly across that vehicle's acceleration time, and then graphed against the Simulation's hypothetical curve attached some time ago.

As expected the sim has difficulty modelling the first few seconds take-off as so many traction variables are at play, but by 3.2 sec it tracks the real data quite closely and the curves essentially sumperimpose. By 26 seconds the real X4 begins to show higher than expected speeds and ends with a top speed 6.4 km/h higher than the sim predicted (260 km/h [161.6 MPH] vs the sim 253.4 km/h [157.5 MPH]). As the video does not identify the track course, the differences in road grade along the way, wind speed or direction, or elevation, it is difficult to make any conclusions on the high end difference, but it seems possible one (or more) of those variables could be influencing that result.

Rob will undoubtedly provide 1/4 mile data once his arrives.

This is great info and chart!
I appreciate all your hard work, i cant wait for mine.
Great news mine started production yesterday.
I think at 500 miles I'm going to drag it

[DrKevM5]

Originally Posted by ROBNYC

This is great info and chart!
I appreciate all your hard work, i cant wait for mine.
Great news mine started production yesterday.
I think at 500 miles I'm going to drag it

What mods are you planning?

[FSociety]

Originally Posted by DrKevM5

What mods are you planning?

Not sure yet really have to see but most likely going to take it slow until turners bring something out.

Originally EnzoPerformance is offering a good discount on the first member to get the X4 M40i or M2 tuned and knowing them personally I'm very tempted.

[DrKevM5]

I've got H&R springs, blackout grills and M Performance rear spoiler waiting to be installed. I've figured the car is going to need about 12mm. spacers for that hella flush look. The reviews state that it has pretty good acceleration so I'll see whether tuning is desired. I may check on that tuning offer for my M2, but I probably won't have the first one.

[ND40oz]

Originally Posted by Max Well

By 26 seconds the real X4 begins to show higher than expected speeds and ends with a top speed 6.4 km/h higher than the sim predicted (260 km/h [161.6 MPH] vs the sim 253.4 km/h [157.5 MPH]). As the video does not identify the track course, the differences in road grade along the way, wind speed or direction, or elevation, it is difficult to make any conclusions on the high end difference, but it seems possible one (or more) of those variables could be influencing that result.

It's showing higher then expected speeds because of how far off the speedometer is. Every BMW I've driven has been extremely optimistic when it came to actual speed versus indicated speed and it gets worse the faster you're going.

[Max Well]

Originally Posted by ND40oz

It's showing higher then expected speeds because of how far off the speedometer is. Every BMW I've driven has been extremely optimistic when it came to actual speed versus indicated speed and it gets worse the faster you're going.

Also a possibility, ND40oz (that the speedometer isn't calibrated correctly). Based on the shape of the curve (now attached for illustration), though, it appears almost as if the latter part of the video may have been filmed on a gentle downslope (negative grade). It tracks nearly identical to the sim's slope for roughly 23 seconds then maintains a much steeper angle than one would expect to see at these speeds with the X4's dynamics.

[FSociety]

Hey Max Well

46F / tire pressure 37 psi all around (bad) / Summer non-RFT tires (too cold for them maybe) full tank of gas (bad for drag)

R/T... 423
60'... 1.935
330... 5.440
1/8...8.406
MPH...82.04
1000...11.002

ET... 13.209 @ 102.36

[ggalanis]

Was the ATS-V stock? It looked to me like it got a bad start, especially compared to yours, but then made up for it big time after ... if I saw right, he was in the 11s... and I remember it being a 12s car, but that would be with a perfect start.

With the HP difference stock vs stock, I would easily expect that the ats-v will be faster than a M40i

[FSociety]

Originally Posted by ggalanis

Was the ATS-V stock? It looked to me like it got a bad start, especially compared to yours, but then made up for it big time after ... if I saw right, he was in the 11s... and I remember it being a 12s car, but that would be with a perfect start.

With the HP difference stock vs stock, I would easily expect that the ats-v will be faster than a M40i

I believe he was stock, it was too cold for RWD cars to hook last night even with my summers it wasn't as good as I expected at 40F
He did 12.6 @ 111

I should be going to a better track next Friday with some forum members a bit further away but its worth it. Going to lower front tire psi a bit it seems too high for fronts. Car only has 1400 miles should be getting faster after 3,000 they say.

[FSociety]

Max Well

i ran again at a better track, 45-50F weather, 33psi front 37 rear, half tank of gas instead of full tank and better weather for summer tires.

R/T....167
60'...1.972
330... 5.473
1/8....8.408
MPH....82.82
1000.... 10.969
E.T... 13.157 @ 103.19

[Max Well]

Greetings, Rob, and apologies for the delay in replying to your posts as I haven't had much time to visit the forum lately. Thanks for sharing your drag times to provide further documentation of the new X4 40i's performance.

I am attaching the Forum drag sheet with your first two entries now recorded. I also plotted your times vs the simulation and the acceleration video curves as well. I imagine you are having a lot of fun in your new 40i!

Max

[Max Well]

Rob - after placing your best drag slip time in your new X4 M40i next to jamoka3's in his 328i xDr with Active Autowerk, and seeing how remarkably close they are across the board, I was wondering if you both have had a chance to race side-by-side? Aside from the performance testing it would appear to be a reasonable competition even though the vehicles are markedly different.

[FSociety]

Originally Posted by Max Well

Rob - after placing your best drag slip time in your new X4 M40i next to jamoka3's in his 328i xDr with Active Autowerk, and seeing how remarkably close they are across the board, I was wondering if you both have had a chance to race side-by-side? Aside from the performance testing it would appear to be a reasonable competition even though the vehicles are markedly different.

we're trying to run this Friday jamoka3

Max Well

[Max Well]

That will be interesting, Rob.

I put together a brief analysis as I was trying to figure out who I think would win - not just the global race but more specifically the split times (which is where my interest is).

To compare I wanted to first figure out the estimated HP jamoka3 is running above the 240 HP stock. The easiest way for me to estimate that was to graph his fastest time from 25 Mar 2016 on the simulation template I posted on the 3 series 1/4 mile drag thread 11 Sep 2015 at 0854AM - that shows both times land on the +50HP curve (therefore 290 HP). So I used the engine efficiency rating of 79.2% which I used for the sim calculations, which gives him an effective racing HP of 230 and you 285 (79.2% of 360). This works out to a weight-to-power ratio of 15.66 lbs/hp for jamoka3 and 14.85 lbs/hp for you.

I'm not a racing expert or aerophysicist but in my simplistic way of thinking since you have a lower wt-power ratio you should be faster early in the race (assuming equal traction etc), and it seems the 60'-660' split times would support that. However, by the 660' mark when speeds are going above 80mph, his aerodynamic profile should begin to catch up and maybe even pull away as you have a bigger, less-aerodynamic box to push through the air. And in the data you both posted, that also seems to begin to show, as he had a faster 1000'-1320' split (albeit only .006 seconds).

Ideally if the track allows you to switch lanes and you can run at least a few versus each other you should get some good data points to see if those trends persist. And as a disclaimer as I have often indicated, I have no background in this area so my logic may be off, but I do enjoy trying to understand the science behind our vehicles' performance marks.

If there is a way to set up a camera angled to see the front of the vehicles while you are racing it should make for some close calls at the Finish Line. Have fun!

[Max Well]

Here is the compilation of ROBYNYC's Drag Slip Data from 18 May and 27 May and the corresponding graph of the fastest time from those days (18 May only had one slip). These two are even closer to the Sim's and /Auto TopNL Video's curves now, and in fact, nearly superimpose.

Rob, if you could film your instrument cluster with an attached digital stop watch (as the /Auto TopNL video shared) during some of your drag runs, it would be possible to develop an actual performance curve for your vehicle from 0 to 13.x seconds. As the drag strip is level ground, it could assist in deciphering the early seconds without concern for road grade changes which complicates the analysis of the other video.

[FSociety]

Max Well not at drag-strip but in a open-road did something similar as i havent gotten back to drag-strip

[Max Well]

Engine sounds great, Rob. Have you noticed much difference in the acceleration and handling at the 5700 mile mark compared with delivery?