Road Atlanta - HPDE input

[kaamacat]

Question for anyone that's been on Road Atlanta recently... I plan on heading with the BMWCCA for their March event, and would appreciate any input on....well anything.

Car is 100% stock so for starters would be curious on any alignment changes you may have made, or, starting/kept tire pressure. (I know GM is saying f38 r37).

THANKS!

[TBone]

Have you tracked there before? I see you previous car, very nice, and wonder.

The obvious thing is BRAKES, BRAKES, BRAKES.
Change out your fluid for Motul600, get some stainless steel lines and some specific track brake pads. I recommend Cobalt Friction XR1 F and XR2 R.

Alignment changes may affect your street ride and wear on your tires. However, as much camber as you can get at both ends will definitely help. -2ish in the front and -1 in the rear or the most you can get out of your car.

I hope this isn't old hand type stuff to you but since you asked I am trying to think of everything I can.

Tire pressure recommendations are for HOT tires so start them off lower and check as soon as you come off track. Also check the tire edge to see if you are at the right pressure.

T.

[Stephen12ZL1]

I used GM's listed alignment specs per the intro video and found my car was almost exactly in spec with GM's recommendations for front and rear alignment. No way to know unless you put the car on the rack to confirm the specs. Definitely get some high temp brake fluid and you can run the stock pads first time out no problem. When you wear out the stock pads, upgrade to pads as mentioned above or Hawk DTC. Start with tire pressure cold at 28-29 psi as pressure will build quickly as heat increases. Your pressure at the end of a session will likely be in the 38-39psi range. Make sure you have changed the rear end fluid before your track runs as the stock fluid is nasty after the first 1500 miles. Use the GM LS gear oil which has the correct additive in it. Run your first session in PTM3 until you learn the car then bump to PTM4 & 5 once you gain confidence and track knowledge. Have fun!

[kaamacat]

Thanks much for the inputs so far...and I'm sure others that may hit the HPDEs will as-well. (QUESTION- How did the GY Gen2's hold up for two days. I know that depends much on the track itself and the driver...)

[JANNETTYRACING]

Originally Posted by kaamacat

Question for anyone that's been on Road Atlanta recently... I plan on heading with the BMWCCA for their March event, and would appreciate any input on....well anything.

Car is 100% stock so for starters would be curious on any alignment changes you may have made, or, starting/kept tire pressure. (I know GM is saying f38 r37).

THANKS!

I Road Race my car with the BMWCCA Here in CT at LimeRock Park.

I run the JRE 75 RWHP Tune package, Cobalt XR1 XR3, Pentosin DOT 4LV fluid, JRE Alignment, and GM recommended Pressures Cold

I consider myself a Rookie Driver but I am quickly coming up through the Ranks, and the car is still Better than I am a Driver.

It Sticks No matter How hard I have pushed it.

Caught Some Air over the hill and got sideways twice No harm no foul just drove through it when I landed.

I am Very impressed with what GM has Provided us, but I felt it lacked power stock and the brakes were fading before the mods.

Now I could not be more satisfied with my ZL-1 at my current driving skill.

Ted.

[Proroc]

Drove my ZL1 there last Fall with the MVP time guys. My car is stock except cold air intake. The Track was green and cold most of the morning so I ran the whole time in PTM 3. That will keep from losing the car in the 3 very dangerous off camber turns when you are exiting the corner and apply the power.

The turns to be very careful in are turn 5, 7 and 10. If you listen to the guys that teach there and watch You-tube you will see a lot of people make mistakes in these turns.

I witness 2 Z06 corvettes, m3, race prep miata all go off in these turns. These were the ones that you could drive away from.

TAKE YOUR TIME and you will have a GREAT TIME!

You can goggle ZL1 Road Atlanta and see some of my on board videos.

Start the tires cold at 32psi. I like to leave the tire pressure display up so I can tell with tire are getting warm. at about 36 to 38psi the grip will get really good and you can push the car and feel it slip before it comes loose. Once you experience this you will understand what i mean.

By the afternoon session you will start to get a good feel for it and get plenty of driving in.

The car is awesome stock. The tires are really good. The brakes are also killer. I am going to better temp fluid because they do get hot under the hard braking.

Enjoy the car it is made for the track and really shines there.

[boondocksaint]

I was wondering, since this is on-topic and a few track guys are in here:

The manual says not to engine brake (I dunno if this is brake-in only, or just not to do it ever). I used that all the time in other cars on track. Any of you do it on the ZL1?

[Stephen12ZL1]

I think what it means is not to let the "gearing" of the engine slow the car excessively. For example....don't rev to redline in second gear and release the throttle for a huge deceleration without using the brakes. For a Miata sized car it is o.k. I think engine braking causes a huge amount of thrust inside the engine which can cause premature wear.

[kaamacat]

Originally Posted by Proroc

Drove my ZL1 there last Fall with the MVP time guys. My car is stock except cold air intake. The Track was green and cold most of the morning so I ran the whole time in PTM 3. That will keep from losing the car in the 3 very dangerous off camber turns when you are exiting the corner and apply the power.

The turns to be very careful in are turn 5, 7 and 10. If you listen to the guys that teach there and watch You-tube you will see a lot of people make mistakes in these turns.

I witness 2 Z06 corvettes, m3, race prep miata all go off in these turns. These were the ones that you could drive away from.

TAKE YOUR TIME and you will have a GREAT TIME!

You can goggle ZL1 Road Atlanta and see some of my on board videos.

Start the tires cold at 32psi. I like to leave the tire pressure display up so I can tell with tire are getting warm. at about 36 to 38psi the grip will get really good and you can push the car and feel it slip before it comes loose. Once you experience this you will understand what i mean.

By the afternoon session you will start to get a good feel for it and get plenty of driving in.

The car is awesome stock. The tires are really good. The brakes are also killer. I am going to better temp fluid because they do get hot under the hard braking.

Enjoy the car it is made for the track and really shines there.

THANKS MUCH. I believe we chatted last (forum somewhere) on the Vids you had going out there with the RS5 friend of yours. Typically I'd have a boatload of AutoX's in a car to get a feel for when she will let loose and the report-back from the car/tires...etc, but have not had the chance this year yet. From what I've seen of the car so-far, I think it will be great on a road course. (Seems to stay settled nicely ... does not upset with road changes too quickly). I was thinking PTM3 as-well.

[G Money]

Originally Posted by kaamacat

Question for anyone that's been on Road Atlanta recently... I plan on heading with the BMWCCA for their March event, and would appreciate any input on....well anything.

Car is 100% stock so for starters would be curious on any alignment changes you may have made, or, starting/kept tire pressure. (I know GM is saying f38 r37).

THANKS!

I too was thinking about going to this event. I use to road race motorcycles out there 25+ years ago and it was a blast. I have never tracked my car on a road coarse and was looking for some help with tire selection. With my horsepower I run drag radials on the street so looking for some advice from those of you who track there car whats going to be my best option for tires on the track ?

[Proroc]

If you have your stock tires still there are pretty good. Just make sure you get them warm before you start to put down the power out to the corners to hard. The car stock will kick the rear out long before you feel it.

Just take your time until you get a good feel for the loud petal. I too did a like of bike time and they are very similar because a bike with a really good tire will slip with out breaking loose and sending over the top or low siding you. The tires on the cars once they are good and warm give you that same feel. When there are cold the will bit you really fast. Your car will all that extra torque will bite you faster.

[jessrayo]

Originally Posted by boondocksaint

I was wondering, since this is on-topic and a few track guys are in here:

The manual says not to engine brake (I dunno if this is brake-in only, or just not to do it ever). I used that all the time in other cars on track. Any of you do it on the ZL1?

They mean don't do it ever. But they are talking about manual transmission only and the context is putting the car in a lower gear and quickly releasing the clutch so the engine drags the rear tires.

I have seen some rod failures on LS engines from drivers that did a lot of engine braking. When you engine brake it pulls the connecting rods and the rods have a lot more engineering focus on handling push form acceleration rather than pull from engine decel. The last rod failure I saw from this was on a ZR1 corvette and our ZL1 weighs a lot more than that vette did. That is the reason to heel & toe and rev match with down shifting, to save the connecting rods. At the very least you should do as much braking as possible with the clutch in and slowly release it just prior to corner entry.

Think about the amount of force when you down shift, dump the clutch and lock the rear tires as the engine builds revs, every bit of that force is pull on the connecting rods. If you do a lot of this it will destroy your engine and that is part of the reason most performance manufacturers have rev matching downshifts, there are a lot less engine failures if you can prevent this.

[ZL1-V]

Originally Posted by jessrayo

They mean don't do it ever. But they are talking about manual transmission only and the context is putting the car in a lower gear and quickly releasing the clutch so the engine drags the rear tires.

I have seen some rod failures on LS engines from drivers that did a lot of engine braking. When you engine brake it pulls the connecting rods and the rods have a lot more engineering focus on handling push form acceleration rather than pull from engine decel. The last rod failure I saw from this was on a ZR1 corvette and our ZL1 weighs a lot more than that vette did. That is the reason to heel & toe and rev match with down shifting, to save the connecting rods. At the very least you should do as much braking as possible with the clutch in and slowly release it just prior to corner entry.

Think about the amount of force when you down shift, dump the clutch and lock the rear tires as the engine builds revs, every bit of that force is pull on the connecting rods. If you do a lot of this it will destroy your engine and that is part of the reason most performance manufacturers have rev matching downshifts, there are a lot less engine failures if you can prevent this.

Jessrayo,

After re reading your post I now comprehend what you are stating. I guess the big difference is as you put it, "locking the rears". I can hear downshifting around the 55 second mark?




Downshift at 1:29?



I don't think I've ever downshifted hard enough to lock the rears!

[STI_TO_SS?]

My insomnia inspired opinion: At about 1:29 I hear brake, followed by rev match on clutch engage, then tire squeal during turn. All good IMHO.