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      11-08-2022, 02:57 PM   #1
RacerBowie
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Videos: SCCA Time Trial - Road Atlanta

November 5-6, 2022. 2015 M235i, stock except for camber plates, 17x9s with 245 Nankang CR-1 tires, and PFC 08 brake pads.

Disclaimers: Data didn't work properly all weekend. The phone GPS just wasn't good enough for any of the 3 apps I tried to consistently pick up start/finish. So there are no useable lap times, if you're super interested you'll have to use a stopwatch.

Sound is awful, again. The video where you can see the driver, that wonderful-ish noise is the heavily modded Camaro I was chasing. I eventually backed off so I could actually hear my own car.

And, as always, the data lags. This winter I'm buying an OBD2 BT dongle and probably a GPS puck before going back out, so maybe next time all I'll have to whine about is the sound.

I shot videos two ways and neither was amazing, so will keep trying different things.

First was Saturday, from the windshield:



This session, if I'm remembering, correctly, was the second of the weekend, so I was working to steadily build speed.

Second video was Sunday, mounted in the rear window looking forward, so you can see the driver. However, when the sun came out it REALLY washed out the view out the windshield, so I dunno what to do there.



This one was a little faster (fastest lap of the weekend should be lap 4 (so maybe 2 laps after the video starts?), with lap 5 being just off it). This session was a couple laps of warmup, then "Send it" for a couple laps, then cool off a couple, then "Send it" one more.

Last edited by RacerBowie; 11-08-2022 at 03:26 PM..
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      11-08-2022, 09:21 PM   #2
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I spectated there a few times when I lived in Atlanta, and I always thought it would be a cool track to drive. Maybe someday.
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      11-09-2022, 02:03 PM   #3
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Quote:
Originally Posted by ggggbmw View Post
I spectated there a few times when I lived in Atlanta, and I always thought it would be a cool track to drive. Maybe someday.
It is right up there at the top of my favorite tracks list... maybe tied with VIR?

Great place to drive, races well (if biased a bit toward cars with torque, makes setting up a pass tough), but MAN is it an unforgiving place if you go off. If there is any track in the US where you should get the TrackDay insurance, it's Road Atlanta!
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      11-09-2022, 04:11 PM   #4
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Road Atlanta is the reverse of VIR. RA = Downhill "S"s, short straight between 6 and 7, long back straight, pucker factor turn 12. VIR = Up hill "S"s, short straight between 11 and 12, shorter long back straight, off camber turn 17. Was told the track designer made an effort to copy VIR.

It was not until I raced RA, and had talks with others, that it hit me about the similarities. Helped me improve my section time between turn 11 & 12 at VIR, I was coasting/lifting between the two (not coasting/lifting at RA 6 & 7, since the distance was longer), thinking it was one turn (not thinking it was two turns).
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      11-09-2022, 08:19 PM   #5
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Got this great shot from the track photog today.

Send it!
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      11-10-2022, 08:35 AM   #6
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Quote:
Originally Posted by Toddbmw View Post
Road Atlanta is the reverse of VIR. RA = Downhill "S"s, short straight between 6 and 7, long back straight, pucker factor turn 12. VIR = Up hill "S"s, short straight between 11 and 12, shorter long back straight, off camber turn 17. Was told the track designer made an effort to copy VIR.

It was not until I raced RA, and had talks with others, that it hit me about the similarities. Helped me improve my section time between turn 11 & 12 at VIR, I was coasting/lifting between the two (not coasting/lifting at RA 6 & 7, since the distance was longer), thinking it was one turn (not thinking it was two turns).
That's a really good point about 11/12 and 6/7. You can lose a lot of time if you don't charge the first one, or at a minimum really had a pass to someone.

And really, South Bend's approach is different than RA turn 1, but thecommitment level to go fast through it is the same. If you have the right pace at turn in you aren't sure you're going to make it until well past the apex.

Interesting comparison that I've never heard made before... explains why I love them both. Thanks!
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      11-10-2022, 04:13 PM   #7
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It's good when you love the way your car looks this much, right?
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      11-14-2022, 04:28 PM   #8
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Are you running a baffled sump or S55 oil pan and pump? I've heard Road Atlanta is one of the danger tracks for our cars due to some of the longer corners.
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      11-15-2022, 08:55 AM   #9
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Quote:
Originally Posted by Cos270 View Post
Are you running a baffled sump or S55 oil pan and pump? I've heard Road Atlanta is one of the danger tracks for our cars due to some of the longer corners.
I'm not, yet. For the time being I'm overfilling by a little more than half a quart and holding my breath.
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      11-19-2022, 11:50 AM   #10
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Quote:
Originally Posted by Cos270 View Post
Are you running a baffled sump or S55 oil pan and pump? I've heard Road Atlanta is one of the danger tracks for our cars due to some of the longer corners.
I'm surprised that Road Atlanta would be considered a danger track. Turn 1 goes a bit long, but it's not that bad. None of the other corners exceed 90 degrees or so.

Turn 9 (the Carousel) at Road America is way longer. Turn 8 at Brainerd is 180+ degrees. And the Keyhole (5) and the Carousel (14) at Mid-Ohio are both 180 long turns also. Brainerd and Road America are my usual tracks, and I live in mortal fear of oil starvation.

In addition to max oil level, I also run a relatively narrow 225 width on my RS4 track tires. Originally started at 225 for other reasons, but sticking with it to keep overall cornering forces lower. Same with the RS4, which aren't as sticky as some options. And it's also a reason I haven't put in camber plates. Hoping that these choices keep me safe enough. And on the upside, they are all also the cheapest choices.
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      11-19-2022, 03:33 PM   #11
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Quote:
Originally Posted by ggggbmw View Post
I'm surprised that Road Atlanta would be considered a danger track. Turn 1 goes a bit long, but it's not that bad. None of the other corners exceed 90 degrees or so.
I understand it's a right-hand turn issue.

If that's the case, I think from T10B turn-in to straightening the wheel after exiting T12 is one very long right-hander (some of it much more turning-right than the rest (i.e., T10B and T12)).

Bowie runs that section pretty consistently between 14.2-14.3 secs, making for a long stretch of turning. His hands also straighten-out a couple of times, whereas if you watch an in-car video from significantly faster cars (LMP3 and BW's E36 Pikes Peak), you'll see the driver is steering the car right throughout the section.

That section also goes uphill soon after starting and then turns into a long downhill before reaching the flat of the main straight. I have no idea what effects upon oil pickup those changes do or don't have.

Oil pressure would seem to be data worth capturing to see if there's an issue with it on that part of the track.
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      11-19-2022, 06:18 PM   #12
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So multiple thoughts:

First, my "knowledge" of the problem with oil starvation was from braking Gs and long LEFT hand turns. Now admittedly the long left handers knowledge I extrapolated from well known issues with older BMW inline 6 engines, but the architecture between the M series and the N series is similar and German engineers have always seemed to do the same things over and over.

In the M20, overfilling is generally good enough until have R compound tires and good suspension. I've been using that logic to hopefully be safe enough until I can get either the MMR baffle in there or convert whole hog to the S55 system.

As far as Road Atlanta... Let's just say I've got enough laps there that my phone auto completes road Atlanta from "road". 😂

In a car like ours, 10b and 12 are two separate turns with a bendy straight between them. You exit 10b in third, straighten briefly, bend back right to go under the bridge more or less under the red square and touch or slightly cross the white line for the pit entry lane, then let the car drift back left down the hill to set up for 12. Shift to 4th and feather the throttle while berating yourself internally for not staying flat the whole way down the hill even though it's a street car with no safety equipment and 12 is fast fast fast.

So there's a sold few seconds where there are no real lateral Gs happening for the oil to settle.
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      11-19-2022, 06:26 PM   #13
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Reading more of Doug's post, there is also a little bit of Negative G while going under the bridge, but it's pretty negligible so I doubt it's doing anything. It's enough to cause a loss of traction in the rain, but not in the dry, for reference.
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      11-19-2022, 08:38 PM   #14
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Quote:
Originally Posted by RacerBowie View Post
Reading more of Doug's post, there is also a little bit of Negative G while going under the bridge, but it's pretty negligible so I doubt it's doing anything. It's enough to cause a loss of traction in the rain, but not in the dry, for reference.
You know, if it was me, I'd call BW and say "What do you guys think?"

As I say, however, that's just me, a guy who always looked to qualified sources when an engineering issue was the subject.
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      11-19-2022, 09:23 PM   #15
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Quote:
Originally Posted by dradernh View Post
Quote:
Originally Posted by RacerBowie View Post
Reading more of Doug's post, there is also a little bit of Negative G while going under the bridge, but it's pretty negligible so I doubt it's doing anything. It's enough to cause a loss of traction in the rain, but not in the dry, for reference.
You know, if it was me, I'd call BW and say "What do you guys think?"

As I say, however, that's just me, a guy who always looked to qualified sources when an engineering issue was the subject.
That's much more intelligent than I usually am, but I'm planning to order some braided brake lines from them next week, maybe I'll ask then.
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      11-20-2022, 04:15 PM   #16
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Quote:
Originally Posted by ggggbmw View Post
I'm surprised that Road Atlanta would be considered a danger track. Turn 1 goes a bit long, but it's not that bad. None of the other corners exceed 90 degrees or so.

Turn 9 (the Carousel) at Road America is way longer. Turn 8 at Brainerd is 180+ degrees. And the Keyhole (5) and the Carousel (14) at Mid-Ohio are both 180 long turns also. Brainerd and Road America are my usual tracks, and I live in mortal fear of oil starvation.
Yeah, I was thinking the same thing, there aren't many "long" turns at Road Atlanta. Maybe someone is confusing it with Road America.
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      Yesterday, 03:04 PM   #17
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Quote:
Originally Posted by dradernh View Post
Oil pressure would seem to be data worth capturing to see if there's an issue with it on that part of the track.
I wish there was a way to easily get oil pressure on these cars, but I'm not aware of any. It doesn't seem to be available on any of the OBD tools that I have, and it's not something I can track in TrackAddict. (Unless I'm missing something obvious.)

If anyone is monitoring oil pressure on track, please tell us how you are doing it.
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      Yesterday, 04:51 PM   #18
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Quote:
Originally Posted by ggggbmw View Post
I wish there was a way to easily get oil pressure on these cars, but I'm not aware of any. It doesn't seem to be available on any of the OBD tools that I have, and it's not something I can track in TrackAddict. (Unless I'm missing something obvious.)

If anyone is monitoring oil pressure on track, please tell us how you are doing it.
If there isn't a means of acquiring the data digitally, I suppose there's the option of installing an oil pressure gauge like this one from ECS: https://www.ecstuning.com/b-innovate...e/inn3913~ino/, or this one from VAC: https://store.vacmotorsports.com/aem...uge-p4510.aspx.
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