Penny-pinching car geek's guide to racing, track days, and car build. DIY projects, product reviews, and interviews.

Tuesday, March 30, 2010

Gainesville Test Track Day Repost - 03/27/10 - Importance of Data Logging

I call the Gainesville Track a test track, but I think its official name is "Gainesville Road Course." Road Course to distinguish it from the more famous drag strip.



Yesterday was supposed to be my girlfriend's first track day, but one of her legal assignment due dates was recently announced to be during the track session. So I went by myself.
Track conditions: No rain. Min 44 Max 77 Fahrenheit. Not much dust or rubber on track (Glad not a lot of people run R-comps here)


I love the morning silence before the first car goes out. This particular morning I arrived at the track to find the gates closed. And I saw a bunch of cop cars on part of the course. Uh-oh. Is the event canceled? A white GTI pulled up behind me driven by a kid in his mid-teens with his father next to him. Cool! When I was sixteen, I never even dreamed of going on track. In fact, driving was something very foreign to me. I think its very good that he is getting track experience at an early age. Lucky to have such a cool father.

My worries proved me wrong and people arrived to open up the gates. I always arrive nice and early to the track. I used to spend this time to socialize with other drivers and make new friends, but in the past year I decided to spend that time by myself. Driving is not a team activity, and I believe that pre-session times are best spent alone. Now I spend that hour or two before the driver's meeting focusing on what I am going to be working on that day. This time I was going to work on hitting all of my apexes, looking ahead and learning the new setup.

I mounted a camera to my right fender to see how close I get to the track edge. Turns out this isn't needed since I should be getting right onto the edge of the track and hanging off a part of my right wheel. Thats when I knew I was getting close enough. Sorry track owners for wearing out the tarmac edge.

First session out. It took me this whole session to get used to the grip levels. Car understeers a bit less, but the on throttle oversteer is gone. I would still like the car to handle a bit more edgy. This is because my low horsepower and my viscous LSD (which by the way, is like not having one) isn't able to overcome the increased rear traction. With more front end grip I should be able to balance the grip levels and drive a more edgy and faster car.

Second session out. I'm used to the grip levels. In this session the temperatures were probably 50 degrees. I did my fastest lap in this session, even though I was no doubt driving better in the later sessions. Still missing apexes on the right side. Fastest time of the day, no doubt because of the air temperatures. I forgot to do a cool down lap and my brakes were smoking! Always remember to do a cool down lap. Fast time is 1:02.7

Third session out. Figured out points of the track I'm leaving time on and added more throttle in those sections. I'm consistently hitting my apexes. Fast time is 1:02.9. Here is a video.



Fourth session out. Grant drives it for a 6 lap stint, sets benchmark time. Had trouble turning the streering wheel because his knees touched the steering wheel. His fast time is 1:01.8, consistently. 

I'm glad Grant is there to drive my car. Someone at the track asked me "he must be a really good friend that you let him burn you tires up." But to me setting a goal is much more important than tires. Track days are not competitive and this is the only way I can push myself to get better.

Fifth session out. I got caught up into doing a fast lap and forgot what I was supposed to be working on. Missed some apexes but I'm consistently going over the curbs I want to go over, driving on the edge of the road when I want to. Discovered that going over the outer curb setting up for turn 5-6 unsettles the car and results in oversteer.

Importance of Datalogging
I went home and watched the video-overlay. I've found that watching these videos is different than looking at my GPS log. Something about seeing my speed and accelleration with an actual visual of the track makes things click. Seeing how much past a certain visual reference mark on the track helps me rememember the sensations and the car behavior that I cannot see from the data. For example, trun 2 and 3 are the same radius, but turn 3 is more off-camber. Why am I going a few mph slower in the first one? I figured out while driving on the course that I can go full throttle in turn 2 entry, but it took me looking at the overlay to realize I should be getting on the gas much sooner.

This time I failed to record Grant's stint in my datalogger, so I compared the P-box data of our prospective runs.
As usual, he is braking much harder for a full half a second shorter in the major braking zones of turn 1 and turn 4. I can't brake that hard yet. Another thing I could not ascertain without datalogging.

Car changes since last event
-Spec miata exhaust installed
-Front ride height increased to 13"
-Bilstein 1994 R-package shocks installed
-New RT-615 tires 

-205mm wide tires on 15x7 wheels
-Track width increased by 16mm


Car Handling
-Still some understeer
-Less on-throttle oversteer

Setup Notes
-More front camber needed
-Ascertain affect of higher front ride height and lower front ride height at the same camber level
s
-Ascertain whether or not it is faster to let the V-LSD do the work, or just wait a bit to get on the gas. Hypothesis is that accelerating early enough to have a  couple of seconds of inside wheel spin until the LSD kicks in is faster, since it doesn't result in any oversteer and scrub off speed.

Conclusion
This event, I felt like I extracted much more out of the track; found some more of the hidden speeds. I think from now on its going to be all about consistency, smoothness, and car setup. I understood the importance of looking ahead couple of corners much more. I hope all of these things move over into my driving when at other circuits.


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