Track Day 39 + 40 -- Thunderhill West Time Attack W/ Reno SCCA -- Rear "diffuser", Replaced Booster, Trailer Improvements!

Leading up To The Event

Coming fresh off the tail of the previous OnGrid time attack weekend, I had some work to do both to my car and my kit.

On the Corvette, my brake booster had failed so that required swapping out. I had hoped for a bit it was just the check valve, but I wasn't so lucky. Fortunately for me a good friend Dave helped me swap it out in exchange for help going to fetch his new RV rig, and he said it was no big deal to do. Lucky!

Next up, I had a bunch of simple maintenance to do. I had to change the oil, swap out rear brake pads, get new tires mounted. I also finished installing the bump stop onto the other side of the front of the Corvette.

I also mounted up a flare style fire extinguisher ie "stick" to at least have something to help deal with a fire, should one occur.

One thing that has been an issue for me is that the rear of the Corvette felt a lot lighter after removing the reaar tube. So I scrambled on the last day I had free to fab up a small rear aero plate, hoping it would help the Corvette feel planted.

Another bit of work I completed leading up to the event was adding a simple tire and fuel jug holder to my trailer. I'll be testing it out on the long drive to the event, but the jist of it all is that I want to be able to bring a weekend worth of fuel with me along with have spare wheels and tires ready to go for both the Corvette and the trailer, just incase.

Lastly, I added some additional kit to my trackside supplies, mostly incase a vehicle needs to get up on my trailer but has had a wheel failure of some sort. So I got a wheel dolly and some "tire sleds" that I can use to help drag a car onto a trailer if need be.

How the Event itself Went

So the drive itself is of course gruelling, coming in around 8-9 hours or so of driving. Overall though, I just checked out, cruise controlled down the highway and all was well with my new tire and fuel jug rack. Arriving at the event I ran into some fellow C5 Corvette friends along with some other good folks I'd met last time. We were all pretty excited going into the event despite the probability of 100 degree plus temperatures.

The first day went well enough, with me setting a new PB about a half second faster, and holding a modest lead over fellow C5 owner and Max 2 competitors, Andrew Kauble. I still should have had a much larger lead over him as I've got a gotte car and full aero... but wrapping up day 1 only a half second separated us.

I had one big off track event at the morning session as I was both relearning the track and getting my new tires going. This unfortauntely pulled a bunch of wind out of my sails during the best session timewise of the day. Ah well, such is life.

The night of the first day Andrew and Bryce were kind enough to offer to let me use their Tech2 setup to bleed the ABS system on my Corvette. It pumped a TON of fluid through the system, and while only barely noticably improving the pedal feel, it at least eliminated any concerns I'd have had about air being in the system and it also ensured I had nothing but fresh fluid on the car.

Day 2's morning session was the big one. It was our one chance to set our best lap for the day, especially as the second session would combine TA1 and TA2, bringing in the Miata's and other slower traffic resulting in much slower lap times. We all went out, we all sent it as best as we could... and I set my new personal best of 1:24.946 according to the transponder, and 1:25.97 according to my 10hz GPS. So for anyone hating on the accuracy of Track Addicts with 10hz gps, it's within 3 hundredths of a second of transponder times.

Unforutnately for me and my hopes to yet again take second for the entire weekend in the Max2 Cateogry, Andrew absolutely sent it in his C5 Corvette beating me by two tenths of a second and securing the second place win. Please not the above times do not include Jason Coopers 1:23 time from the day prior, securing him first place. Still, that was some damn good driving from Andrew, and his car doesn't have near the amount of aero and lightening modifications done to it. He absolutely crushed it out there, and with that he certainly earned his finishing place of one spot higher than myself! I'm still happy to have made big improvements since the time I was here last, and I look forward to more future improvements as time goes on!

Results Event #5
4th overall out of 22, 2nd in class of 4

Results Event #6
2nd overall out of 15. 2nd in class of 4

Comparing New Best Time to Previous Best Time

Track Map to help ensure we're all talking about the same thing:

Lap Times (New PB left/first, Old PB right/second)

Hopefully you're able to see the two lap times side by side. I think the big takeaways here are comparing turn speeds and top speeds. Temperatures were 12 or so degrees hotter, the car was 150lbs lighter, I was on 315's instead of used 295s, I had the Z06 geared trans, and it had 10-15 more hp/tq accross the entire powerband I use on track (3000+).

Front Straight: I had higher speeds on my 1:26 lap by a half MPH. I think the additional temperatures wasn't letting me take much advantage of the additional power I could produce.

Turn 1 & 2: Speeds were about the same. I think I may be able to corner more with slightly lower temperatures, but after test driving Andrew's Corvette I think softening the rear of my car could help as well.

Turn 2 to entry of 4: Speeds were up slightly. Probably horsepower.

Turn 4 and straights etc through 6: Corner speeds and top speeds were all pretty similar!

Straight Before turn 6 through Turn 7: Top speed on the straight was up 5mph! Pretty damn substantial! Top speed was also up just a hair through turn 7 by 2mph. Slower in and faster out is much easier to consistently put down.

Turn 8-9: Top speed is up, but likely limited by traction over the crrest and late into Turn 9.

Turn 9-10: Speed is up 3mph or so, which is a nice boost despite the temperatures.

Thoughts for Next Event

With some reduced temperatures I would expect to be able to produce a bit more power, and perhaps improve corner speeds further. I do start to experience concerns with oversteer though as I approach the limits, and could sometimes get the car to understeer. I'm thinking I'll soften the rear sway bar, adjust the front bump stops I put on the car, and in general see to my suspension settings. I also think some fresh brake pads wouldn't hurt. Depending on black Friday sales... I may even treat myself to an extra set of wheels and some time attack specific tires for next season!

I do still need to further improve my data acquistion and probably start looking into tuning the car myself.