track observations

[westwest888]

I ran with the advanced group today with the Audi Club at Thunderhill. New to the car since last time is: Pilot Super Sports, a custom alignment job, upper control arms from 034, spherical lower control arm bearings from 034, and Alu Kreuz. Existing was the 380mm front brake kit and Pagid yellow pads on all 4 corners - this continues to perform *flawlessly*.

This time out I started obsessively monitoring tire pressure, tire temperature at the middle and edges, and brake rotor temperature. The door panel says inflate to 41 PSI - this is important for a car this heavy on XL rated tires. I started by bleeding it out to 36 PSI front and 38 rear. First mistake - this track is mostly left turns so the right side of the car takes a beating. So a good starting temperature is 2.5 to 3 PSI lower on the right side - it will heat up by itself. Over the course of the day I let out a total of 9 PSI right and 7 PSI left. After each session I evened the car out to 38 PSI hot. The idea is that while the car was in motion it should max out at around 43-44 PSI.

I was also monitoring rotor temps. After a 75% speed session of 20 minutes, the fronts were 480 degrees and the rear about 405-410. A full tilt balls out session the fronts were 525 degrees after a cool down lap. After about 3 minutes on the paddock they cool to 450. I think this is OK. The temps are in Fahrenheit.

The suspension is brilliant. I can say the alignment is near perfect and based on tire temps I probably could have gone more aggressive on camber. I'm -2.1 rear and I could do -2.2 (max for this car on stock springs). I could probably go -2.8 in front instead of -2.6 in front. I base this idea on how the outside tire temp is slightly higher (10%) than the inside.

My times were around 2:20 this morning, cold. I didn't get times from the end of the day where I had some really fast, consistent, smooth laps (all within 2 seconds of each other). I reverse engineer the times from the track photographer's time stamps.

[Leor604]

Thanks, West.

Great info. I assume any understeer is officially banished. No rolling over onto the sidewalls?

[ilspazzaneve]

Thanks for sharing west...it's a lot of work instead of enjoying your day...

curious about the same things Leo is, sidewalls and the understeer.

If you have an iPhone or GPS-enabled iPod touch or iPad, and a way to mount it on your windshield, you should get the TrackAddict app or Harry's Lap timer.

[GeoJoe]

Great details here. How are you getting the rotor temp data? +1 for Harry's lap timer

Now lets see some pics!

[westwest888]

Eh. I've seen iPhones fly out of cars that were allegedly secured to the windshield. Fortunately, the guy worked for Apple and had no less than 17 of them for "testing". I am terrible at baseball but I actually caught it in the passenger seat.

[westwest888]

Rotor temp data is from a laser pyrometer.

Sidewalls look good and I've been watching them. The tire temps are slightly higher on the outside than the inside. The tire is only going to get screwed if I drive the car wrong and scrub speed with the tires. There's no roll; I looked at the pics in the photographer's trailer. No roll, you can see the camber in the phot, and you can see the inside tire gliding over the curb no problem. I have the 034 aluminum end links, which I neglected to mention at the top.

[Akatsuki...]

Good info... Thanks.

I am impressed with how u have no roll w out sways or suspensions

[Quattroborn]

Good thread. I have a few slightly different opinions. 1. Where your tire pressures start are completely irrelevant. 2. Your optimal tire pressure is a function on desired handling and even temperature saturation. A tire pyrometer is the best way to understand what's going on inside the tread and tire wear can help you flag a number of other things (alignment specs, driving style, etc.). 3. Your eventual hot tire pressures are what you want to achieve and notate. Keep good notes because hot pressures are car specific, tire specific and track specific.

[CircuitTested]

This time out I started obsessively monitoring tire pressure, tire temperature at the middle and edges, and brake rotor temperature. The door panel says inflate to 41 PSI - this is important for a car this heavy on XL rated tires. I started by bleeding it out to 36 PSI front and 38 rear. First mistake - this track is mostly left turns so the right side of the car takes a beating. So a good starting temperature is 2.5 to 3 PSI lower on the right side - it will heat up by itself. Over the course of the day I let out a total of 9 PSI right and 7 PSI left. After each session I evened the car out to 38 PSI hot. The idea is that while the car was in motion it should max out at around 43-44 PSI.

I was also monitoring rotor temps. After a 75% speed session of 20 minutes, the fronts were 480 degrees and the rear about 405-410. A full tilt balls out session the fronts were 525 degrees after a cool down lap. After about 3 minutes on the paddock they cool to 450. I think this is OK. The temps are in Fahrenheit.

The suspension is brilliant. I can say the alignment is near perfect and based on tire temps I probably could have gone more aggressive on camber. I'm -2.1 rear and I could do -2.2 (max for this car on stock springs). I could probably go -2.8 in front instead of -2.6 in front. I base this idea on how the outside tire temp is slightly higher (10%) than the inside.

My times were around 2:20 this morning, cold. I didn't get times from the end of the day where I had some really fast, consistent, smooth laps (all within 2 seconds of each other). I reverse engineer the times from the track photographer's time stamps.

Good stuff man...looks like you had fun. Pagid yellows are happiest a little hotter so don't be afraid to brake deeper if you're comfortable. You got 2 tons of sedan...put some heat into those things!

Also, do yourself a favor and get a G-Tech or Vbox at least. Data really is key if you're serious about shaving off times. If you wanna start getting really into it try the AiM Solo. AiM makes some fantastic data hardware.

[westwest888]

Good stuff man...looks like you had fun. Pagid yellows are happiest a little hotter so don't be afraid to brake deeper if you're comfortable. You got 2 tons of sedan...put some heat into those things!

Also, do yourself a favor and get a G-Tech or Vbox at least. Data really is key if you're serious about shaving off times. If you wanna start getting really into it try the AiM Solo. AiM makes some fantastic data hardware.

I've looked into the data acquisition devices. I don't have a Windows computer and I'm kind of a software snob. I'm willing to pay $700 but not for some piece of junk written in Visual Basic. I'm holding out for something cloud based, or something really cheap made with an Arduino and a Raspberry Pi running open source software and hardware. The BMW club is prototyping something like that for their events. Stay tuned.

[ilspazzaneve]

Eh. I've seen iPhones fly out of cars that were allegedly secured to the windshield. Fortunately, the guy worked for Apple and had no less than 17 of them for "testing". I am terrible at baseball but I actually caught it in the passenger seat.

You can run TrackAddict or Harry's without video, too, just mount it down low. Still very useful, especially if you use an external GPS and can analyze your sectors. If you have a Kiwi you can even put throttle position, temps, any engine parameter.

Circuit, I hear you got rid of the S4...! Too bad, if true. Happy you're still contributing.

[CircuitTested]

I've looked into the data acquisition devices. I don't have a Windows computer and I'm kind of a software snob. I'm willing to pay $700 but not for some piece of junk written in Visual Basic. I'm holding out for something cloud based, or something really cheap made with an Arduino and a Raspberry Pi running open source software and hardware. The BMW club is prototyping something like that for their events. Stay tuned.

Check out the AiM stuff. I run their Evo4 and MyChron 3 dash (with about 5 add on channels) in my other car. Software is fantastic...unbelievably powerful and it is what most serious drivers use. I used to have G-Tech and yeah the software wasn't great but it did the basic stuff, it was cheap and a snap to use.

[CircuitTested]

You can run TrackAddict or Harry's without video, too, just mount it down low. Still very useful, especially if you use an external GPS and can analyze your sectors. If you have a Kiwi you can even put throttle position, temps, any engine parameter.

Circuit, I hear you got rid of the S4...! Too bad, if true. Happy you're still contributing.

Not true! She is still alive and well...but more or less retired to civilian duty...I picked up a dedicated track car.

[ilspazzaneve]

Not true! She is still alive and well...but more or less retired to civilian duty...I picked up a dedicated track car.

After realizing after a few track outings in the S4, how far away in both performance and fun it is from my NSX, I sorta gave up on taking it to the track as an alternate. Asides from installing Brembos and RE-11s, I picked up springs, sways, links and adj arms that I never installed, but westwest is frankly getting me thinking about it all over again.

Hope you get out in that S4...it must sound like a total beast with the headers.

[Leor604]

Well if I had an NSX.....

Unfortunately, no track toy for me so the S4 has to do it all, which is why I don't want to go overboard with solid bushings, stiff suspension etc. Also why I went with ADS.

Love NSX's!

[westwest888]

At this point I could make an argument that solid bushings are more every day live able than aftermarket springs on a B8. Even my girlfriend thinks the car feels safer and rides better. They're not making crazy noises even after the wicked abuse I gave them this weekend.

[Akatsuki...]

After realizing after a few track outings in the S4, how far away in both performance and fun it is from my NSX, I sorta gave up on taking it to the track as an alternate. Asides from installing Brembos and RE-11s, I picked up springs, sways, links and adj arms that I never installed, but westwest is frankly getting me thinking about it all over again.

Hope you get out in that S4...it must sound like a total beast with the headers.

You have a local S4 owner who would pick up some of those parts off you if you never installed them... :)

[ilspazzaneve]

At this point I could make an argument that solid bushings are more every day live able than aftermarket springs on a B8. Even my girlfriend thinks the car feels safer and rides better. They're not making crazy noises even after the wicked abuse I gave them this weekend.

This completely shatters the stereotype, happy you went in a totally different direction. So are springs out for you then, or still a consideration? What was next in your list?

[ilspazzaneve]

You have a local S4 owner who would pick up some of those parts off you if you never installed them... :)

Hahaha maybe, seriously, brand new in the box, available, and tax and duty paid. But let's let this thread shake out first...

[Akatsuki...]

At this point I could make an argument that solid bushings are more every day live able than aftermarket springs on a B8. Even my girlfriend thinks the car feels safer and rides better. They're not making crazy noises even after the wicked abuse I gave them this weekend.

West can you describe what the solid bushings do a lil bit?

And have you thought about putting a bucket seat in your car? I have one that I just bought.. but I am still contemplating about putting it on my car.. cause my car is my Daily and I am not sure if I wanna have that kinda seat on my daily.

[westwest888]

This completely shatters the stereotype, happy you went in a totally different direction. So are springs out for you then, or still a consideration? What was next in your list?

Next I'm actually going to look at stage 1 software and a free exhaust, purely for enjoyment and senses. The dead spot in 3rd and 4th gear near 5500 RPM is starting to screw with my happiness. I can feel the supercharger dumping everything out the bypass valve. I feel bad the for faster cars I'm passing because my car is dogging the straightaway.

[westwest888]

West can you describe what the solid bushings do a lil bit?

And have you thought about putting a bucket seat in your car? I have one that I just bought.. but I am still contemplating about putting it on my car.. cause my car is my Daily and I am not sure if I wanna have that kinda seat on my daily.

They preserve static alignment settings. When the car gets moving at 1G the rubber bushings in the lower control arms will give and flex, and your alignment bends out of whack. It also provides a more direct connection to the road because its metal on metal. You can feel a low frequency of vibration from the road, almost like when you drag a garbage can over concrete. The B8 cabin is so isolated and the servotronic steering is so numbing that this hooks up your hands to the road again. I think it would be brutal in a B6 but it's quite civilized in a B8. My friends with low miles E46 M3 track cars can't believe how drive able, civilized and comfortable my car is.

[westwest888]

No plans to change springs. Will replace struts at 50k miles (24k on clock now).