JackOlsen

A week ago, I drove two days with NCRC/ARC at Thunderhill. They're a great group for both DE and racing, and I took a better set of tires with me than the BFGoodriches I normally drive on.

My best time previously at Thunderhill (with the cyclone) was a 2:05.7, on the BFGoodrich tires. This time, with a mismatched set of used Hoosiers, I was able to do a 2:01.5 with the bypass, and a 2:04.5 with the cyclone.

I only got one clean qualifying lap with the cyclone layout. Looking at the video, I think I could easily do a 2:03.xx with the same tires.

But then, I haven't done that yet. And that's where any of you who know Thunderhill well can help. I don't think I'm driving it very well, and could definitely use some pointers from anyone who sees obvious mistakes in what I'm doing.

So, here are videos of two laps (one with the bypass, one with the cyclone) in WMV format. They're huge (20 megs or so each), so you'll need a fast internet connection, and you should right-click and save them to your hard drive before watching them.

I also put together a clip with a few mistakes and as many other cars as I could fit in. It's even bigger (about 50 megs), but if you were at the event, you might see your car -- and if you watch it, you'll get to see me go off track at the exit of the bypass.

Here are the videos:

Lap with the bypass (20 megs)

Lap with the cyclone (20 megs)

Passes and bloopers (50 megs)

I'm beginning to like the track more, although -- if you're familiar with it -- you'll see that I'm still not driving it as cleanly as I ought to. There's definitely more time still on the table.

Any advice from the fast guys?

Tom W

Jack: Did you talk to Arnaud? As you know, I'm not the fastest, but I have a couple suggestions to try. I'm convinced that the double apex line is faster through turn 2. I gain a car lenght or more on most that use the "traditional line". I think Arnaud likes to take 3 a bit wider (but I usually take the line you do). I also think that a later turn in and apex at 11 allows you to straighten out the esses a lot more. I'm not sure that it's much faster. I also don't go to 2nd gear at 14, I think staying in 3rd is faster. I only go to 2nd at turn 11.

Wreck Me Otter

Mainly, I wouild say that you're not carrying enough speed through the corners in general. You leave quite a bit of track on exit and you don't touch the exit burms...

From the camera angle, it is hard to say much about specific corner positions....it's easier to see what is going on from a location near your head.

mooty

jack... my slow and humble attempt.

arnaud's cup car and my GT3 can't stick to the inside of T3 very well. it's easier for us to go in wider, but in lighter cars like miata or m3, i can almost hug the inside all the way.

most cars can do T14 in third gear. carry more speed into it, turn in very late, get front right into the ditch. that's where i aim since front right is not loaded anyways. then i not only carry speed intot the turn, i also have more pavement for the next turn. your cyclone video, you turn in pretty early and you had maybe 2 feet or so to the inside berm, i would get on it. as far as i can tell on T15 (last turn), you want to get on both the apex and exit berm to straighten the track out more and get more speed.

the esses. in gt3, i goto 2nd gear, but i have to upshift 1/2 way through it.
in m3, it's got shorter gears, so i leave it in third and force myself to go in faster.

i can't see where your car is relative to the apex berms, but 60% of the exit berms you don't even touch them. if you did, you would easily shave another 1.5 seconds off if not more.

AW

Jack,

First off, 2:05 in an older 911 is flying. 2:01 with the bypass is even better. There is a 1 to 2 seconds difference usually so it appears you can really go faster at 5

here are my uneducated guesses:

Turn 1. You have more on your right at turn in and more track at the exit. You should be on the floor at or around the apex (or earlier)

Turn2. I cannot see your inside line on the video, however you have 3-4 feet on the track out that you could use to carry more speed

Turn 3. Be a bit more patient and really get inside (compromised for 4)

Turn 4. Try to use more track on the exit

Bypass looks great

Turn 6 and 8 you are leaving 3-4 feet on the track out

Turn 9 you are leaving even more. You cannot really the track out when you turn but it is there and you get get a wider radius

Esses: if you compromise the exit of the 1st corner a bit you can better align the rest such as you take everything straight. Use all the track on the outside

14. Turn a bit later and hit the apex

15 looks good

With the cyclone, I think you can carry a lot more speed.

In general, I think you can shave time by using more track and going faster at 1, 8 and 5

Arnaud

AW

Here is a 1:56 vid and motec map with the bypass. I'm sure the car could go faster with a driver mod.

Cup car thill 1:56

Here is the motec map of that lap:



Of course I had my shares of "interesting" moment. During the 2nd race the 2nd day I was running out of tires and lifting / catching a bit too much at turn 2...

Here is that vid!

Cheers,

AW

JackOlsen

Wow, thanks Arnaud. That gives me a lot to work with. I'm going to dig out the data from my DL-1 system for comparison, and see (aside from your car's superior grip, stopping power, and acceleration) where I can find a little more time.

I agree with everyone about my cautious track-out points. Part of that is that I'm still learning the track; part was my mismatched tires; part is just where I need to push things a little more. Staying in 5th for turn 1 is something new to try. I'd stay in third for turn 14, but my 2nd is very tall, which means my car probably runs better there in second than most 911's would.

But again, this gives me something to work with. That Arnaud is getting 130 before turn 10, 133 before turn 14, and 146 before turn 1 is amazing, to me. My car's absolute top speed is only 136, and my data logger never shows me getting higher than 122 on my fastest lap. Arnaud's slowest speed is 53. Mine is 47.

I ran 2:01's for three sessions in a row, so I think it's a fair baseline time with me. With the cyclone, I only got one fast session, and even the 2:04 was with me having to slow down in traffic in turn 2 and then not accelerate out of 2 because of the pass. I think it's fair to say that a 2:03 would have been easy with an open track, since most guys run a 2-second difference between the two layouts.

Tom W

Jack: Good luck in your quest for better times. I plan to continue to work on it too. One thing to remember - for a 3 mile track with lap times about 2:01, it takes an average speed of "only" about 0.7 mph faster to drop another second.

mooty

146 before turn 1 is amazing
__________
gee.... if i did very well coming out of T15, when i hit brake marker 4 at T1 i am only at 130 in my street GT3.

JackOlsen

I went through and compared speeds point by point between Arnaud's Motec data and my DL1 data. I'm attaching an image file with my speeds added in red. According to my reading, Arnaud is anywhere from 4 to 24 mph faster than me at just about every single point around the track.

Oddly, I had faster speeds at two specific points. One is under braking for turn 9, where Arnaud drops to 68 mph, while I only drop to 72. At first, I thought this might just be an example of me doing better at that particular turn's entrance. But Arnaud is carrying so much more speed (18 mph) than me by the end of the straight between 9 and 10 that it could as easily be an argument that I'm overcooking the entrance to the turn without any discernible gain in speed or segment time. The 18 mph gap is similar to the one between us before turn 8 or before turn 14.

I also have a slightly faster exit top speed out of turn 10 before the braking zone for 11 (94 to his 90. This could be explained by me reading the data wrong, or Arnaud just not running that turn as well as he could on that particular lap. Or it could be another example of me braking later for turn 11 and sacrificing my line through the esses for the sake of a little more speed when it doesn't matter as much.

All around the track, Arnaud's speeds are significantly higher than mine. I'm going to look at the specific gaps later, and try to see how each one might be explained by 1) my lesser skills, or 2) his better grip, or 3) his better power.

AW

Great data! Thanks for sharing. I'll try to go faster at 9 and 10. Honestly, haven't focused on these turns for a while... How much does your car weight?

AW

JackOlsen

The specs on my car: 2500 pounds (2700 with driver and safety equipment), estimated 250 crank horsepower, Turbo brakes, 265/315 (old, RS03) Hoosiers.

viperbob

Wow Arnaud, it seems like you are getting use to the car. The Motec stuff is really cool. Glad it is working now. 8K RPMs on the front stright huh. I thought you were going to keep the revs down a little . Take care.