Friday, May 22, 2009

Track Day #10 -- 2009/05/21

Yes, I had another track day. This time I went to an open track day event put on by AR Auto Service for experienced drivers. There were about twenty folks so plenty of open laps without much traffic. The mix of cars was mostly high performance sports cars and race cars; lots of GT3s, a few Miatas, BMWs, Ford GT, etc. In terms of raw performance, my poor little WRX was way outmatched here. I think there was maybe one Audi out there running slower lap times than me, but most folks quite simply blew my doors off.

The day was an open track even, meaning that they didn't divide us out into run groups. They basically just had 30 minute sessions where you were welcome to get right back in line to pre-grid on the next session if you wanted to. Track went hot for quiet/street cars at 8:30AM (or 9:00AM for race cars) and went cold at 4:00PM; with 30 mins off for lunch (Yummy lasagna catered in).

All this meant is that I had WAY too much track time. My first realization was that anything more than 30 mins at a stretch is really a bad idea. I ran half a session and stayed in line for a full next session and it was way too much; I need more breaks in between sessions. The other thing is that I got my full about mid-afternoon (2pm) so didn't really use up anything close to my full potential.

My plan for the day was to experiment with different things (both driving and car setup):
  • Zero out the toe when changing camber and evaluate.
  • Evaluate the Hawk Blue rear brake pad upgrade.
  • Experiment with tire pressures.
  • Play with lines and weight transfer, etc.
So, my results... well, I'd say they're kind of mixed. First observation is that I can't tell all that much from zeroing out the toe. It grips a bit better in T4 and doesn't wander so much on the straights, but the lap time didn't improve dramatically.

The second observation is that the Hawk Blues are a nice pad, and I can definitely feel the grip there (once it's bedded in) but it's probably not worth the extra money. I was able to get better trail braking into T7, and T1 was pretty consistent; but the pad was wearing pretty quickly and my data logger tells me that my overall braking performance wasn't really that much better. I'll probably stick with HP+ in the future.

Now on to tire pressures... that's an interesting one. I originally tried to shoot for 40 PSI front and 45 PSI rear (hot) and get pretty good feel out of it; however, I get quite a bit more tire noise in T12 when set up this way which goes away when using higher front pressures. I took a look at the tire temperature with my infrared pyrometer and I'm seeing about 160 on the outer edge, 162 in the middle, and 157 on the inner edge. This implies that I'm slightly overinflated and not running enough camber (even though I'm maxed out on camber). One observation I did have is that I had my fasted lap during session 2 where I had the tires set too high (48 PSI on the front left); so that argues (perhaps) that I need higher pressures? Clearly I still have some work to do here. One observation I did have is that track temperature has a huge impact on whether I can get a good lap time or not. The second session of the day was cool and dry (maybe 60F) and I was never able to reach even close to that time for the rest of the day as it warmed up. My best laps were always within the first 5 laps and then things settled out. I don't know if it's simply tire heat or if it's pressure related.

Now on to my driving experiments. First thing to note is that I stopped shifting down to 2nd gear for T7; I just left it in 3rd. According to my data logger this is definitely the right thing! By doing this, I'm able to hit another 1-2 MPH by the end of the back straight, so it's going to be my normal approach here. I also played around with braking early and accelerating into T7 apex vs braking later and trying to get it to rotate down to the apex. In general, I think braking early and accelerate through works better. With the Hawk Blues I am able to rotate the car under brakes, but I've got to be more careful about it -- it's very easy to overdo it and end up missing the apex.

The other experiment I was running was to try to carry more speed through T5 and that worked out really well; a slight lift/touch of the brakes and then accelerate out. My problem then shifted down the track a bit to the transition of T6 where I was having a really tough time getting set up. The problem with T6 is that I'm carrying so much understeer through T5 that I have a bit of a "moment" as I transition from the right hander (T5) to left hander (T6). It's probably a matter of smoothness, which I'm working on; but also dealing with the understeer.

I didn't really play that much with T10-T11; just doing what I did last time, but not as aggressively. I know I can hit that better than I am, but it's also one of those things that requires some commitment from me and I had enough to work on. :-) I did try a few things in the chicane though (nice safe place to have some fun) -- mostly trying to get the car to rotate better for the left hander coming out of T2. Sometimes I got it, sometimes not. Occasionally, the car would rotate so well that I'd run up on the curb more than I'd like; so clearly I need more work here too (or just play it safe and not try to "drift" it around here...).

My fast lap for the day was 1:34.3 which is 0.6 seconds faster than my previous best. Here's my fast lap comparison from my previous best. As you can see, staying in 3rd gear for T7 really helps me get a good pull onto the back straight and propels me to almost 120 MPH. The interesting thing is that with all the better here but worse here parts in the lap, I'm actually at a dead heat for the entry of T12. This means that my pull onto the front straight was where I found my time. All the rest is just lost opportunities. :-)

And here's the video of the lap:

Here's some pictures of the other cars at the event. It was a lot of fun running with these guys, even if it meant they were blowing my doors off -- all except for the black Lamborghini who was going at a nice controlled pace; probably didn't want to risk the nice car. The Subaru guys came over and we chatted for a bit; he was running about 1:25-1:26 lap times, so clearly out of my league. He seemed to like my lines, so maybe I don't suck as much as I thought.

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