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      10-01-2018, 08:24 AM   #1
dre99gsx
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Where is the maximum grip level of our cars

This is too generic of a question, but I found myself presumably at the very limit of my setup this past weekend at Thunderbolt. I beat my best time 1:33.9 , and my setup is nothing special (beside the extra horsepower).

R888R (now reaching 40HC), cheap BC racing coilovers, minimal aero, solid brakes, -3camber fr, -2camber rear.

I found myself trail braking into every turn, getting the rear to slide but controllable (not tail-out drifting), pointing to the apex, getting on the gas earlier, continuing a minimal slide to trackout, and hitting the gas hard. It was turn after turn. On occasion, I would come in about 2-3mph faster into the turn, and she would plow, so I knew the limit and stayed on it.

I've seen other lesser powered Z4s do some amazing times on this track with 3.0si or S54 power, so this all comes down to setup in my opinion.

- Would you say that I'm just at the limit of the car itself in its current state? - Without going to slicks, would you also say that any more adjustments is only going to net me minimal returns? Could there be another 2-3 seconds to gain considering I spend almost no time coasting, and am either on brakes or on gas, running the school-taught line.

Don't get me wrong, I'm having a blast sliding this thing around Would be nice to get some feedback on our Z4 platform on where she just can't do anymore because not-race-car.
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      10-01-2018, 12:10 PM   #2
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Great lap time at Thunderbolt! I assume that is without the Chicane? Here are some thoughts that come to mind after reading your post, hopefully some of it is helpful.

- This is really tough to assess without digging deep into your data traces; however, break down Thunderbolt into 3 or 4 solid sectors, then identify what your best lap would be if you strung your best sectors together. How far off was your best lap?

- Be careful with making adjustments to your settings with R888R tires at 40HCs. They are going to be more than a few seconds slower than when new.

- There is a new AI data acquisition tool that mounts to your dash called APEX PRO. Basically, by using a series of LEDs, it attempts to answer your exact question in real-time. I've seen some pretty good reviews on it and you might want to look into it further: https://apextrackcoach.com/

- You mentioned 'driving the school line'. You might want to check out some open track days with no-point-by passing. Driving off-line so frequently adds another challenge to train yourself on and helps teach you how to carry speed through corners in ways that normal DEs do not 'typically' allow.
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      04-21-2019, 06:53 PM   #3
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Originally Posted by Azeka1 View Post
Great lap time at Thunderbolt! I assume that is without the Chicane? Here are some thoughts that come to mind after reading your post, hopefully some of it is helpful.

- This is really tough to assess without digging deep into your data traces; however, break down Thunderbolt into 3 or 4 solid sectors, then identify what your best lap would be if you strung your best sectors together. How far off was your best lap?

- Be careful with making adjustments to your settings with R888R tires at 40HCs. They are going to be more than a few seconds slower than when new.

- There is a new AI data acquisition tool that mounts to your dash called APEX PRO. Basically, by using a series of LEDs, it attempts to answer your exact question in real-time. I've seen some pretty good reviews on it and you might want to look into it further: https://apextrackcoach.com/

- You mentioned 'driving the school line'. You might want to check out some open track days with no-point-by passing. Driving off-line so frequently adds another challenge to train yourself on and helps teach you how to carry speed through corners in ways that normal DEs do not 'typically' allow.
Old post but forgot I had this video, not mine but friend lent me his APEX unit to mess around with. If you do buy, just remember probably better to keep it on your side of the car. Having it center requires you to use your peripheral which isn’t so easy.

Anyways video isn’t terribly exciting since not many folks wanted to drive in the wet but you can see how/what the APEX communicates at certain corners...



School line is the safe one that works for everyone. There’s certainly faster lines but keep in mind racers have a shit ton of aero so their line may not always work for u. I tried someone’s suggested line at Thunderbolt few years back and had a nice 4 off incident lol.

Dre 1:33 is pretty damn fast but I think you can find another 2-3 seconds before jumping to Hoosiers. Honestly, best way to learn is to ride shotgun with a faster driver and see what they’re doing. That’s how I always found out where I was dogging it lol.
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Last edited by 3002 tii; 04-21-2019 at 08:05 PM..
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      04-21-2019, 08:56 PM   #4
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Great info! I actually achieved 1:30.0 this year on same setup, just better driving. I feel there is more in it since I'm still feeling out a few corners, but the culprit came down to the 40+hc R888Rs. On new R888Rs this season, the difference was drastic immediately.

The question still stands - at what point are you at the limit of what your car can do, and how do you know?

And this goes into deeper philosophy of DE: Unless you have a goal to be instructor or move onto racing, and lap times don't win you any trophies (probably bragging rights), how do you keep from getting bored!

APEX unit seems cool btw!
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      04-21-2019, 10:00 PM   #5
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Originally Posted by dre99gsx View Post
Great info! I actually achieved 1:30.0 this year on same setup, just better driving. I feel there is more in it since I'm still feeling out a few corners, but the culprit came down to the 40+hc R888Rs. On new R888Rs this season, the difference was drastic immediately.

The question still stands - at what point are you at the limit of what your car can do, and how do you know?

And this goes into deeper philosophy of DE: Unless you have a goal to be instructor or move onto racing, and lap times don't win you any trophies (probably bragging rights), how do you keep from getting bored!

APEX unit seems cool btw!
Competition for sure... win or lose it’s just as exiting as your first day of DE. If I wasn’t so busy with ‘life’ I’d be all over time trial this year.
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