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Discussion Starter #1
I just completed my first track day at willow springs(fast flowing roadcoarse 2.5 miles i think). The car has cusco front and rear bars, and Hotchkis links. No other mods. Overall it was a good experience. The car got lots of attention and took several people for rides. Most people thought it was just some rice racer until they saw it go. Corvette Z06's are by far the most popular car. Most run slicks or serious treaded track tires. In my group, the Z06's couldn't really hang in the turns but of course had the power in the straights. It really pisses them off too. I actually got the finger from a few as i drove by. This is a contrast from the autocross event i went to last week. On a 50 or so second course the corvettes beat me by 5-7 seconds every time(track tires, slicks). I think the driver's of the vette's today are probably why i could beat them, because it doesn't make complete sense that i could destroy them in the corners the way i did. A couple of observations.

1) Despite the stiff rear sway bar(24mm) i cannot balance the car very well, understear remains.

2) The car tracked better with the diff set on 50/50, I thought 35/65 would have work better.

3) Horrible gas mileage, approx. 7 gallons per 30 min. session, about 21 laps, 7.5 miles per gallon (yes you read that right).

4) the stock tires at stock pressures were destroyed at the end of the day. It looks like they overheated and the outer half of the tread surface severly "chunked". After only 1800 miles they are ruined.

5) While talking with some of the vette owners, my straight speeds were about 9 MPH slower, an 19 mph slower than the Viper GTS. As for the vettes, almost all of the time lost could be regained under braking, and the first turn turn(90deg. banked left hander with a crest at the exit). Seems pretty weird to me, that out of all the vettes in my calss this seemed to be true. It's gotta be poor driving on their part, it must. The last turn on this track is rather hairy, and tends to draw you in too early. It promises a trip into the dirt if your line and throttle control are just a little off. I think this freaks out the guys with rear wheel drive, and sometimes the speed difference at the end of the straight was almost nothing.

Anyway, sorry for the long post but i figured you potential track guys might be interested.

Can anybody recommend good street/ track tires? AB
 

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It sounds like you're not pushing the car hard enough.... I know that sounds funny, but that's my guess. 7.5 mpg is quite a bit higher than I've heard most people getting on the track (i've heard lots of 5's, and even a 4....). Understeer is supposed to be throttle controllable, but you might also have experienced it because you were in lock instead of open differential.... basically, driving the car harder would've gotten rid of some understeer and shown you lower mileage more consistent with other STi's on the track.

As for tires, I think they'll hold up better under higher pressure, but I don't doubt that you could find a better compound for the track that would be better overall. Tires will wear pretty fast on the track though. Unfortunately I don't know enough about tires to give you any specific brands/tires, but I'm sure someone here will be able to help you with that.


Sounds like you had lots of fun, congrats at your tracking experience, and keep tracking that car - it begs to be driven hard. :)
 

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Thanks for the informative post.

I'm thinking of tracking my STi in the future as well and am trying to read as much as I can about it before going so that I can have the right expectations and get the car ready as well.

I've heard that apart from stiffening the car a bit that one of the key things on the STi is to change the brake pads and improve the cooling there. Not sure if others can confirm this?

The condition of your tires is scary though. I wonder if that is standard.

Thanks again!

Steve
 

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Discussion Starter #4
I tried the diff in auto and every step of lock. I have a fair amount of track experience mostly sportbikes and i know what you mean about weight transfer (nothing transfers weight like a 150 hp sportbike). There are several corners at willow where you can change steering, on the gas, off, in between, all in the same corner. I pitched the car sideways into turns. speaking of that, if you pitch it in and stand on the gas the rear end bites and some understeer is felt. Even if i don't touch the gas or go neutral the rear always bites. Don't get me wrong it is cornering with serious bite, but i think it needs some camber or something. I forgot, after the track i monitered tire temps with an infrared thermometer and the insides are about 140 the middle was usually around 165 and the outside was approaching 200, and that was after a cool down lap. I personally think that is too hot. The rears were a little cooler but not much, and I chunked all four just the same. The MPG figures are a guess by looking at my fuel guage and estimating how much fuel was used. The needle was always between 1/2 and 1/4 at the end of 30 minutes. I noticed brake fade early in the day but later on i was scrubbing more speed by throwing it a little sideways. The fade was pretty much consistent though when it occurred.
 

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Re: so a slight understeer is... okay?!?

With street tires, you definitely need to increase the pressure well above normal levels to deal with the heat generated by lapping. From the description of your tire temps, passing Z06s on corner entry and relentless understeer, I would speculate that you were entering corners too fast, but I'm in no position to criticize.

Do you want a street tire that you can occasionally track? Or do you want a track tire that you can occasionally street? For the former, I'd suggest S-03s (but put alot of pressure into them for track use -I used 48 psi for my S4), Falken Azenis dominate certain AutoX classes, so they might be worth a look, but I don't know how they handle heat from lapping days. For the latter, Pilot Sport Cups seem to be popular, but I've never driven them. I have RA-1s on the Miata, and drive them to/from events all the time.
 

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Discussion Starter #6
your probably right. i might have been entering too fast. In some of the longer corners gentle throttle application would eventually mean understeer. Guess i would like just a more balanced feeling in general. My dealer was aginst the idea of going above factory recommended pressure. They said they had seen failures of the sidewalls. Since I was the only sti there i hood nobody to compre notes with on tires. I have been thinking of the RA-1's, which are popular and i am sure i could find lots of track specific data. Thanks for the input. AB
 

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STi Headunit installation made easy

At Thunderhill I run 8 psi over in front and 6 psi over in rear and all is well. No chunking, no sidewall blowout. Thunderhill has quite a few "fast" corners as well that really put your tires to the test. 3 mile track with 15 turns, a few of them are 90+ sustained in the STi. Managed 5 mpg up to 6.5 mpg, but I tend to keep her in lower gears longer for exit speed and power. Have found that "auto" on the diff works wonderfully, just have to learn to have faith that she'll do what you're telling her too. I tried running loose rear (oversteer) and "felt" faster, but manage to turn better times running "auto", coming in with proper entrance speed and squeeeeezing throttle through the turn. You can feel her squat down and pull through it. Much happier than oversteer IMHO. Almost a go-cart feel.
I have found the same interesting behavior with Vettes and SVT Cobras on track: tear them to pieces through the corners, but they catch you in the straights. SVT had me by 24 MPH at the end of the long straight, but if you ride their ass through the corners they tend to come in hot and end up cooking their brakes. Still sucks hearing that supercharger SCREEEEEAAAAAMING up behind you, even if you know you're going to catch him again. I guess if we had 390 horses like they do we wouldn't have that problem, eh?
Keep on runnin'.........MM
 
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