Where I am and where I'm going...

So I figure I should try to jot down some notes on where my S2000 is at this point, my impressions and where I'd like to go from here. My ultimate goal is to be competitive in the SpeedVentures S2000 Challenge Street Class. Obviously, most of the work needs to be on driver improvement (as I've only done a handful of track days with the S2000 so far), but I want to at least build a competitive car sooner than later. The S2000 Challenge Rules.

Right now I've got a stock MY2003 S2000 with the following point modifications:
1.25 = APR GTC-200 Wing
1.50 = Bridgestone Potenza RE-01R Tires

That's a total of 2.75 points out of the 5.00 points possible to stay in Street Class. Where I'd like to go in terms of point modifications:
1.25 = APR GTC-200 Wing
3.50 = DOT-R Tires (Toyo R888 or Nitto NT-01)
0.25 = OEM CR or APR GT Front Bumper

I think the DOT-R tires will give me a definite advantage over running street tires, especially in the summer heat when even the best street tires will start overheating within a few laps. Supposedly, they are worth about 2 seconds at Buttonwillow, but I am willing to bet that the difference is larger than that, especially once the car is optimized for R-compounds. Also, I am going to try a little trick to get the staggered 225/255 tire setup to behave more like a nonstaggered setup by increasing the grip of the 225 tires (by putting them on AP2 rear wheels with a 10mm spacer to get 17x8.5 +55). Also, I plan to get a CR front end or APR GT front bumper to increase downforce in the front as well.

Of course right now I've also got a good amount of "free" modifications, that is, modifications that don't count as points:
SPC Camber Kit Front
4 x AP2 Rear Wheels (Front and Rear)
Carbotech XP10/XP8 Brake Pads
Goodridge SS Lines
Recaro SPG on Taitec Rails
K&N Drop-In Filter

I'd also like to make some changes in terms of the "free" modifications.
Add SPC Camber Kit in the rear
Upgrade to Carbotech XP12/XP10 Brake Pads
Replace with StopTech SS Lines
Replace with MY2008 Front Suspension
Replace with MY2004+ Rear Swaybar

When I had the front SPC Camber Kit installed, I had hoped that I would be able to get around -2.8 camber in the rear so I could run -2.5 front and -2.8 rear. Unfortunately, while the rear right was able to get -2.8, the rear left maxed out at only -2.4. This was the weak link that forced me to go with -2.4 all around. My current alignment specs:

Front Camber: -2.4
Front Castor: 6.5
Front Toe: 0
Rear Camber: -2.4
Rear Toe: 1/8" toe-in

From my last session at Streets of Willow, I felt like the car was a bit too loose, especially without the help of the rear wing in low-speed turns (30-60mph). I would get corner entry oversteer, mid-corner understeer that would sometimes snap out, then corner exit oversteer. So mostly oversteer that required a very careful right foot and lots of correction to the steering wheel. Running worn-down RE-01Rs probably didn't help the cause here.

I really don't want to solve the problem with messing with camber. I believe that there is an optimum camber angle for a given tire and suspension setup, and messing with it to adjust handling characteristics will result in less grip. That means I'll be out there next event with a probe-type tire pyrometer to measure the temperature spread across the tire. I'll be doing this especially if I upgrade to DOT-R. I am willing to bet that both the front and rear tires will want more negative camber, which will necessitate me installing the SPC Camber Kit in the rear.

Next, to tackle the oversteer issue, I think I will try installing MY2008 front suspension (hopefully the whole coilover if I can find a used set for a good price, otherwise just the spring). This will increase the front spring rate from 249lbs/in to 284lbs/in. Yes, that seems like only a little, but my spring rate ratio would go from 249/306 to a much more manageable 284/306 (almost equal spring rates all around). If this doesn't solve the problem, I may opt to install a thinner rear sway bar, either by swapping sway bars with Fil (from 27.2mm to 26.5mm) or buying a 2004+ rear bar (27.2mm to 25.4mm).

I also think that the extra grip of the R-compounds will require an upgrade to the brake pads. From Carbotech XP10/XP8 to a more temperature resistant XP12/XP10, which also has more bite. As far as brakes, I've never been satisfied with the feel of my brakes. I think I will do a complete brake job sometime in late May or early June involving a complete brake caliper rebuild, replace the Goodridge SS kit with some made by StopTech or Endless, adjust the parking brake, inspect the lines, etc. There is a weak link somewhere, and I will find it (I suspect it may be as simple as a parking brake adjustment).

The next event coming up is S2KC #5 at Buttonwillow Raceway. When I was last there with Redline, I was able to do a 2:12.9 with a passenger and a bit of traffic at the end. I think without a passenger and without running into traffic, I would have done a 2:11.7 or so. Supposedly a wing is worth about 4 seconds at Buttonwillow, and R-comps are worth about 2 seconds, so if I everything goes well and I can get my act together, I stand to lose 6 seconds or so next time, which would put me in the 2:05 range. Last Buttonwillow event, Street Class was won with Emilio's best lap of 2:06.9. I'm sure he's got some new tricks up his sleeve, so it should be an interesting match... not that I would hold such lofty dreams of actually winning Street Class... not yet at least.

In preparation for this next event, I need to order some new rear pads. Since I'm planning on going up a step, I will order XP10 rear pads (so I can order XP12 front replacement when the time comes). Then, I need to acquire 4xAP2 rear wheels and get some DOT-R's mounted on them. I will either have to machine out two wheels to fit the front 70.1mm bore, or I might run a 5mm spacer in the front. Who knows, maybe I'll get lazy and just run the 225 R-comp on the 7" front wheel...

My goal for the next event is to figure out how to optimize what I've got. This means taking my angle indicator and playing around with the rear wing's angle of attack to find the perfect tradeoff between downforce and drag (hopefully my G2X datalogger will help in this department). This also means figuring out how to use a tire pyrometer and optimizing tire pressures and figuring out approximately how much more camber I need to dial in.

Based on my impressions at the next event, I will most likely install the front MY2008 springs, install rear SPC Camber Kit, then get the car realigned once the front springs settle (if I buy them new). I figure if I still want more rear grip, I could always swap out rear sway bar later which shouldn't affect my alignment at all.

This should be interesting...