[Max Well]

Originally Posted by chrisbrown44

Where do post questions about my 2005 BMW X3?

Greetings, Chris - here is the link to the general forums by model. Scroll down to the E83 'First Generation X3' General Forum and you should be set. Good luck!

https://x3.xbimmers.com/forums/

[GT500R]

Originally Posted by AlexFL

For comparison, here are two more X5MC 0-62 mph runs. Based on those runs, the new X5M does not seem to be significantly quicker than X3MC. This is somewhat consistent with the carwow X6MC 0-60 result of 3.5 sec.

I see 0-100 mph in around 8.6ish?

I can't remember what the X3M does it, but think it is around the same time.

[AlexFL]

Originally Posted by GT500R

I see 0-100 mph in around 8.6ish?

I can't remember what the X3M does it, but think it is around the same time.

C&D measured for X3M 8.0 sec 0-100 mph.

[Max Well]

Originally Posted by GT500R

I see 0-100 mph in around 8.6ish? I can't remember what the X3M does it, but think it is around the same time.

Originally Posted by AlexFL

C&D measured for X3M 8.0 sec 0-100 mph.

If you look at the acceleration curve I shared in post #90 (using my actual 1/4 mile data points and the two high speed points from the X4MC) - https://x3.xbimmers.com/forums/showp...0&postcount=90, 100mph falls at ~ 8.1 sec. Although somewhat inexact as the curve is approximated between the points, it should provide a reasonable estimate of time to any speed during the first 27 sec for a stock X3MC/X4MC.

[CosmosMpower]

Originally Posted by AlexFL

C&D measured for X3M 8.0 sec 0-100 mph.

When I test drove one on that BMW M tour it felt nowhere near a 8 second 0-100 car, I was thinking 10 seconds at best.

[AlexFL]

Originally Posted by CosmosMpower

When I test drove one on that BMW M tour it felt nowhere near a 8 second 0-100 car, I was thinking 10 seconds at best.

I measured 8.8 sec using dragy... without launch control. 8 sec is correct.

[Max Well]

Originally Posted by CosmosMpower

When I test drove one on that BMW M tour it felt nowhere near a 8 second 0-100 car, I was thinking 10 seconds at best.

The height and cabin dynamics will fool those used to the line-up you show in your stable (F80, F87C, GT3, Mk7 GTI). But the numbers don't lie. And these are fully documented as you know.

For some of us, that is the beauty of what BMW has been able to design with this series (F97/98). It seems to defy Physics with what it can do, and provides an all-in-one for those wanting M performance and also needing utility. In a perfect world, yeah, four- or six- car garages with small performance coupes to provide the performance kick and then daily all-arounds might be ideal, but not all of us have the finances to go that route. This is one vehicle which can satisfy both.

And this one does.

[Max Well]

As we globally begin emerging from restrictions in the upcoming months, I'm using my image from Nov '19 now to encourage anyone heading for a day at a Track or a Strip to share your data here. If you want to document in your own dedicated threads, not a problem, as I’ll migrate the data here for reference. We can start a Leaderboard of sorts: stock, stage1, stage2, and beyond if desired, and I’ll prepare the spreadsheets analyzing interval times as long as slips (and ideally DAs, octane, …) are provided.

Would be interesting to have track videos and data as well, so not just ¼ mile data.

[GT500R]

Originally Posted by Max Well

As we globally begin emerging from restrictions in the upcoming months, I'm using my image from Nov '19 now to encourage anyone heading for a day at a Track or a Strip to share your data here. If you want to document in your own dedicated threads, not a problem, as I’ll migrate the data here for reference. We can start a Leaderboard of sorts: stock, stage1, stage2, and beyond if desired, and I’ll prepare the spreadsheets analyzing interval times as long as slips (and ideally DAs, octane, …) are provided.

Would be interesting to have track videos and data as well, so not just ¼ mile data.

Once one of the tracks I usually go to open up I’ll certainly get you some track times

Working on my launch now for non comp (stage 1 91 tune)

[Thewolfbmw]

Originally Posted by GT500R

Once one of the tracks I usually go to open up I'll certainly get you some track times

Working on my launch now for non comp (stage 1 91 tune)

Figured I would add to the collection. Non-Comp on 21" comp wheels.[IMG]undefined[/IMG]

[Max Well]

Originally Posted by GT500R

Once one of the tracks I usually go to open up I’ll certainly get you some track times Working on my launch now for non comp (stage 1 91 tune)

Originally Posted by Thewolfbmw

Figured I would add to the collection. Non-Comp on 21" comp wheels.[IMG]undefined[/IMG]

Thanks, looking forward to your slips.

I'm thinking it might be helpful to have performance categories to allow apples-apples comparison of interval times, and to then compare across categories to show the gains each stage can produce.

Maybe: Stock non-Comp ['SNC'], Stock Comp ['SC'], Stage 1 non-Comp ['St1NC'], Stage 1 Comp ['St1C'], Stage 2 non-Comp ['St2NC'], Stage 2 Comp ['St2C'], all higher mods maybe Stage 2+ non-Comp ['St2+NC'] and Stage 2+ Comp ['St2+C']

What I haven't been able to figure out so far, is whether we even need to segregate the non-Comp from the Comp models once you enter Stage 1, Stage 2, or Stage 2+? Have we figured out that a Stage 1 non-Comp runs the same as a Stage 1 Comp? If so, then we'd just need 5 categories - SNC, SC, St1, St2, and St2+.

To keep it simple was thinking to lump 'bone stock' with non-tune modified stock such as lowering, wheels, diffuser/splitter, ... , but we can easily make another category if desired.

[AlexFL]

Originally Posted by Max Well

Thanks, looking forward to your slips.

I'm thinking it might be helpful to have performance categories to allow apples-apples comparison of interval times, and to then compare across categories to show the gains each stage can produce.

Maybe: Stock non-Comp ['SNC'], Stock Comp ['SC'], Stage 1 non-Comp ['St1NC'], Stage 1 Comp ['St1C'], Stage 2 non-Comp ['St2NC'], Stage 2 Comp ['St2C'], all higher mods maybe Stage 2+ non-Comp ['St2+NC'] and Stage 2+ Comp ['St2+C']

What I haven't been able to figure out so far, is whether we even need to segregate the non-Comp from the Comp models once you enter Stage 1, Stage 2, or Stage 2+? Have we figured out that a Stage 1 non-Comp runs the same as a Stage 1 Comp? If so, then we'd just need 5 categories - SNC, SC, St1, St2, and St2+.

To keep it simple was thinking to lump 'bone stock' with non-tune modified stock such as lowering, wheels, diffuser/splitter, ... , but we can easily make another category if desired.

Max, I fear it’s even more complicated. For example, GT500R ran on a St. 1 91 octane BM3 map which yields ~4% less hp than the corresponding 93 octane map.

[GT500R]

What’s 19hp among friends Alex

[AlexFL]

Originally Posted by GT500R

What’s 19hp among friends Alex

I must say 3.3 is a killer time under these circumstances. Will you get downpipes or try E30?

[GT500R]

Originally Posted by AlexFL

I must say 3.3 is a killer time under these circumstances. Will you get downpipes or try E30?

I’m getting some decent 93 octane, running a 93 tune 0-60 and see what that does.

Then will run E30 at a later time and that’s as far as I’ll go. Although I probably will test the 100 octane tune too just for fun.

[Max Well]

Originally Posted by AlexFL

Max, I fear it’s even more complicated. For example, GT500R ran on a St. 1 91 octane BM3 map which yields ~4% less hp than the corresponding 93 octane map.

Good point, Alex. So we keep the five main categories mentioned earlier (SNC, SC, St1, St2, and St2M+) and ask everyone sharing their slips to document the conditions. As example, all St1 Drivers can easily compare their times to see why someone else might have been better if pertinent info is provided - DA, tire psi, octane, less weight (in fuel with forged tires or without spare or moon roof) etc. Take the only real slips we have to date, my run vs Nate's slip, and you can see he had better octane, but I had better DA and less weight (in fuel and w/o moon roof and spare). So as more slips come in each variable may become less (or more) relevant to the end result.

If someone has 10 runs on one day, I can easily add all to their own spreadsheet, conditionally format so the fastest intervals can be spotted, and transition the fastest of those 10 runs to the their category's main group. And then, take the fastest of that category's slips to make it that representative in the overall Leaderboard.

Sounds complicated but now that they're all set up, will be a snap to enter the data. What I'm not willing to do is try to find missing data like octane, DA, ... If everyone contributes the information which makes analysis more compelling it should become a reasonably helpful reference as to how to maximize the performance of the F97/98. And ideally, for full documentation - would be helpful to share an image of the vehicle with window number at the track day.

As mentioned in an earlier post, Dragy contributions are welcome anytime but given the inability to confirm location, date, true slope, ... will reserve the spreadsheet slots for those with sanctioned slips.

[robopp]

Originally Posted by Thewolfbmw

Figured I would add to the collection. Non-Comp on 21" comp wheels.[IMG]undefined[/IMG]

That's stock? If so, gesh! My stock RS3 ran a best 3.54 0-60 and weighs 1000lbs less. Did you mess with tire presure? I found significant gains going to a very low tire pressure. Obviously don't want to drive like that, but at the track made a huge difference.

Waiting to get my windshield replaced on the RS3 then I take delivery of my X3MC. I cannot wait.

[Max Well]

Originally Posted by robopp

That's stock? If so, gesh! My stock RS3 ran a best 3.54 0-60 and weighs 1000lbs less. Did you mess with tire presure? I found significant gains going to a very low tire pressure. Obviously don't want to drive like that, but at the track made a huge difference.

Waiting to get my windshield replaced on the RS3 then I take delivery of my X3MC. I cannot wait.

I think you're spot on with the tire pressure issue, at least at the track I've run. Here's a close-up image of the track-tire interface from Nov 2019, and you can see how glass smooth it is. I definitely noticed a big difference going from OEM rec psi settings 33F/38R in Nov '19 to 32F/35R in Feb '20.

Next time out I'm planning on 30F/32R and expect, at least at GNV Raceway, traction should be improved once again. After those trials I'll change to race gas to see what gains I get. Incremental changes so I can assess what makes a difference.

[GT500R]

Originally Posted by Max Well

I think you're spot on with the tire pressure issue, at least at the track I've run. Here's a close-up image of the track-tire interface from Nov 2019, and you can see how glass smooth it is. I definitely noticed a big difference going from OEM rec psi settings 33F/38R in Nov '19 to 32F/35R in Feb '20.

Next time out I'm planning on 30F/32R and expect, at least at GNV Raceway, traction should be improved once again. After those trials I'll change to race gas to see what gains I get. Incremental changes so I can assess what makes a difference.

Very odd that your traction is an issue on stock power. Running the stage 1 tune with 36 / 39 psi yesterday on the streets yielded a small hop and then take off with a very acceptable 1.6x 60’

[Max Well]

Originally Posted by GT500R

Very odd that your traction is an issue on stock power. Running the stage 1 tune with 36 / 39 psi yesterday on the streets yielded a small hop and then take off with a very acceptable 1.6x 60’

Actually, it seems quite understandable to me - not sure why it seems ‘very odd’ to you?

Even with just stock power the X3MC has a very good Wt/hp ratio, and on a smooth surface and with DSC off, it makes sense that tires may not grab at higher psi under different road/track conditions. I think I had mentioned in my GNV Raceway thread that it felt just like a belt sander at take-off with little grab back in Nov’19, and in fact, in the pre-lanes while waiting, a number of other Drivers were noticing the same thing with their launch control (even some with slicks), so they were lowering their psi and brake releasing rather than using launch control to improve traction.

When I lowered the psi from 33/38 to 32/35 on my next series of runs in Feb, the 0-60 foot times improved significantly (2.010 sec vs 1.824 sec on average – see attached image), despite a much lower DA and cooler temps (which one would expect to actually hamper traction rather than help it). Nothing else was different, other than a few gal less fuel in Feb (which would’ve made the car lighter if anything). So at least here at GNV Raceway, for my X3MC, it clearly seems to perform better with lower psi settings. I’ll test that hypothesis further the next time out, as I’ll run at 30F/32R then. No doubt there will be a sweet spot for all of us at our various tracks and roads, so what works here may not be applicable to you on your roads. For those interested, here are some links which discuss Coeff friction and track/tire interactions.

“Coefficients of Friction of Various Roadway Surfaces” : https://marules.com/wp-content/uploa...aySurfaces.pdf

https://www.onallcylinders.com/2016/...icks-traction/

https://www.autoweek.com/racing/nhra...r-a-drag-race/

[GT500R]

Originally Posted by Max Well

Actually, it seems quite understandable to me - not sure why it seems ‘very odd’ to you?

Even with just stock power the X3MC has a very good Wt/hp ratio, and on a smooth surface and with DSC off, it makes sense that tires may not grab at higher psi under different road/track conditions. I think I had mentioned in my GNV Raceway thread that it felt just like a belt sander at take-off with little grab back in Nov’19, and in fact, in the pre-lanes while waiting, a number of other Drivers were noticing the same thing with their launch control (even some with slicks), so they were lowering their psi and brake releasing rather than using launch control to improve traction.

When I lowered the psi from 33/38 to 32/35 on my next series of runs in Feb, the 0-60 foot times improved significantly (2.010 sec vs 1.824 sec on average – see attached image), despite a much lower DA and cooler temps (which one would expect to actually hamper traction rather than help it). Nothing else was different, other than a few gal less fuel in Feb (which would’ve made the car lighter if anything). So at least here at GNV Raceway, for my X3MC, it clearly seems to perform better with lower psi settings. I’ll test that hypothesis further the next time out, as I’ll run at 30F/32R then. No doubt there will be a sweet spot for all of us at our various tracks and roads, so what works here may not be applicable to you on your roads. For those interested, here are some links which discuss Coeff friction and track/tire interactions.

“Coefficients of Friction of Various Roadway Surfaces” : https://marules.com/wp-content/uploa...aySurfaces.pdf

https://www.onallcylinders.com/2016/...icks-traction/

https://www.autoweek.com/racing/nhra...r-a-drag-race/

Depends on the track prep also, if drivers were noticing that they were not getting traction in Nov'19 vs. getting better numbers in Feb (lower DA hinders traction but helps with ET's, especially with a 1100 DA swing) it could account to better track prep combined with cooler temps. More to this then just moving the tire pressure down unfortunately (DA, track prep, tires more worn in, previous person running down the lane, etc. etc.).

Just noticed:
3 PSI in the rear and 1 PSI in the front won't make that much of a difference based on my drag racing experience of 100+ runs down the track.

[Thewolfbmw]

Originally Posted by robopp

That's stock? If so, gesh! My stock RS3 ran a best 3.54 0-60 and weighs 1000lbs less. Did you mess with tire presure? I found significant gains going to a very low tire pressure. Obviously don't want to drive like that, but at the track made a huge difference.

Waiting to get my windshield replaced on the RS3 then I take delivery of my X3MC. I cannot wait.

Stock non-comp.

Summer tire (Continental) with less than 400 miles on them. I thought it was a little cold for the tires. Just took snows off a couple days before.

Though I did run a 3.66 with snows on, exact same spot. (will post)

For the 3.64 run....1/2 tank of gas, spare tire removed, 21's rims tire temps were between 64 and 68. Front 37 psi and rear 39 psi. I do have sunroof.