C-Street BRZ 192 Build Info

[Sccabrz192]

Figured I'd start one of these now that the 2014 season is underway...

If no one else reads it, at least I will have access to my notes when needed!

First off the basics...
A little about me, my name is Tim, I've been autocrossing with the SCCA since 2005, driving an ES 91 MR2, STX 05 WRX, and a BSP/ASP 2007 Solstice GXP along the way. I am a dual member of the Detroit Region and the NorthWest Ohio Region. In 2013 I took a break from the sport when my son was born, and now trying to build my own car for the first time since 2006 when I sold my MR2.

My more recent drives have definitely pushed my driving style to be more of the get the car pointed the right direction and get on the gas as early as possible, so far in my experience I'm getting a lot of corner-entry push that I haven't been successful in getting rid of, this car really wants to take a more speed maintenance line, and that I need a lot more practice with.

Details about the setup, I'll keep this updated as things progress:
2013 BRZ Premium, 6MT with no options
StranoParts Front Sway Bar
Koni Sport Single Adjustable Dampers - off the shelf valving
Nameless Performance Axleback with 5" mufflers
HKS Drop-In Filter
EBC Yellow Stuff brake pads
Schroth Rallye-4 harness
OE "Crash" bolts

Wheels/Tires:
Enkei RPF-1 17x7 et+42 with 235/45R17 Dunlop ZII
As well as
Stock Wheels with 235/40R17 Dunlop ZII

[Sccabrz192]

After a nice wake-up call of finishing 10th of 13 at the Wilmington Match Tour last weekend, I had an opportunity to go to Grissom AFB in Peru, IN for the Indy Region Test and Tune.

My experience:

Yesterday was a great day out at Peru, started in the low to mid 40s and gradually warmed to mid 60s in the afternoon. Sun was shining all day long.

I started off with the setup I left Wilmington with, which I knew needed work.
My first 5 runs were with the 235/45R17 ZIIs mounted on the RPF1's which had 13 runs from Wilmington. Made a front tire pressure adjustment and lowered the rebound on the front dampers considerably for the next 2 runs and found it much better.

After a break and some data analysis I switched onto a brand new set of 235/40R17 ZIIs mounted on the stock wheels. Immediately the gearing difference was noticeable, but there was also considerably more push on corner entry than there was on the previous tires, I never really found a setup that was balanced to my liking as the first set was. I struggled much of the rest of the day to match my time from the 235/45's and only managed 2/10ths slower. Later in the afternoon I switched back to the 235/45s and found 1 of those 2 tenths back. In the fastest section I was on the limiter on both sets, but not enough for either to really benefit from shifting, I tried it with no success. I hot lapped both sets a bit, with the cool ambient temperatures I never got the temps up to where they started falling off, good news I probably wont need to pack a tire sprayer in the immediate future!

FWIW, I'm not going to claim the taller tire is faster, especially after 1 test and tune and the shorter tire was penalized to the tune of 5 lbs per corner with the stock wheels and the narrower wheel offset, but I am thinking there isn't a significant advantage one way or the other... 2/10's is noise at this point as far as I am concerned, but they do require some adjustments behind the seat. Naturally, I found I was on-throttle much early and longer with the 45 tires, and was able to maintain higher levels of throttle input through most of the high speed sections, compensating for the reduced acceleration with the taller gearing. While the acceleration was dulled compared to the 40, I found it was more predictable, and turn in was sharper. I'm sure spending more time on the 235/40 I'll find those to ultimately be faster, but maybe not to the amount I was anticipating.

In the afternoon I had issues with setting off the panic ESC system in the slalom. In the morning I had tried to attack it smooth, managing the entry speed and gradually accelerating through. In the afternoon, I tried to be more forceful in attacking it, entering the first cone at as high of speed as I could, applying brakes (man these EBC pads have a ton of bite!), then turning in, breathing on the throttle and initiating each turn earlier than the last to stay ahead as the car transitioned. The first time was great, worked well and was, I feel, much faster than my morning runs. My second attempt triggered the panic ESC system, and every run after that did the same. I had never done the pedal dance and didn't know the sequence to try it and with no data network in the middle of nowhere-indiana, wasn't able to look it up. So I'll have to try that remedy at another time.

Unfortunately, I had an issue with the memory card on the data logger and lost nearly all the data from the day, lots of video to try to sort through and make some judgements, but not as helpful as the data I was expecting to have. I was hoping I could use it to determine how much faster I was making it through the rest of the course before the slalom was screwing up my times. Oh well, such is life.

Finally, one of the more disheartening things of the day... at the end of the day I hopped into the FP Solstice GXP for 2 runs. 2nd run was a full second faster on index than my best BRZ run of the day... and I was a second slower raw time than the car owner and his co-driver. Ugh.

[Sccabrz192]

My best run from Wilmington... which was terrible.

[ame]http://youtu.be/CvWDIRxBLas[/ame]

Run from Peru where the ESC interference is very noticable

[ame="https://www.youtube.com/watch?v=NPdFZexovpE"]Peru TnT ESC in Slalom - YouTube[/ame]

Compared to a much better run earlier

[ame]http://youtu.be/wCjBv2SpSBM[/ame]

[Rexpelagi]

Interesting comments on the 235/40's. What kind of pressures were you running on the different sets? Also, where are you running the Konis?

I think your first post may be off as you mentioned you had two sets of 245's, not 235's. :-)

[Sccabrz192]

Originally Posted by Rexpelagi

Interesting comments on the 235/40's. What kind of pressures were you running on the different sets? Also, where are you running the Konis?

I think your first post may be off as you mentioned you had two sets of 245's, not 235's. :-)

Thanks for the catch, fixed

I am at 29 R 33.5 F on the 40 and 29 R 35 F on the 45. The pressures still need more tweaking, i just set it where the wear was good and the car felt comfortable. Thinking the next concrete event ill drop the front pressures a little more and see if that helps it bite.

[Rexpelagi]

Originally Posted by Sccabrz192

Thanks for the catch, fixed

I am at 29 R 33.5 F on the 40 and 29 R 35 F on the 45. The pressures still need more tweaking, i just set it where the wear was good and the car felt comfortable. Thinking the next concrete event ill drop the front pressures a little more and see if that helps it bite.

Those pressures are right around what I run.

Do you have the Konis set to the softer end?

[Sccabrz192]

1/2 from soft front, 3/4 from soft rear.

At Wilmington it was 1 1/4 from soft F, 1/4 from soft R

[Rexpelagi]

Originally Posted by Sccabrz192

1/2 from soft front, 3/4 from soft rear.

At Wilmington it was 1 1/4 from soft F, 1/4 from soft R

OK, your TnT setup is very close also. I don't know if the 40's being new had something to do with it - maybe you could try again at a later date now that they are both heat-cycled.

[Sccabrz192]

Definitely could be, even before I started making adjustments the car felt much more predictable and grippier on the 45s, even in the cold, than it had at Wilmington. Which were sticker tires at that event.

[SeanRTR]

Originally Posted by Rexpelagi

OK, your TnT setup is very close also. I don't know if the 40's being new had something to do with it - maybe you could try again at a later date now that they are both heat-cycled.

Quick thread jack from Tim, but have you decided if you're going to stick with the RX-8, or try running the BRZ again?

[Rexpelagi]

Originally Posted by SeanRTR

Quick thread jack from Tim, but have you decided if you're going to stick with the RX-8, or try running the BRZ again?

I think I will focus on the BRZ this year. My RX-8 isn't a perfect example. I'm missing about -1° camber on the left front, and I know the engine in this particular car hasn't always been the strongest performer. In addition, I really like the way the BRZ front end responds to inputs and the minimal roll it exhibits. I do feel more comfortable in the car as well, and driving to events will be 1/3 less expensive.

That being said, I'm not convinced the RX-8 isn't faster, if only slightly. It feels stronger coming out of slower corners and the grip is definitely there. For me I guess it is just a preference thing.

I changed my DC pro registration to the BRZ, so we will see how that goes. For some reason only Mark Andy seems interested in the RX-8, so that will be my comparison point. I know his RX-8 is much better sorted than mine is.

[Sccabrz192]

John,

Any plans this weekend? You should make the trip to Perrysburg for the NWOR event on Sunday

[SeanRTR]

Originally Posted by Sccabrz192

John,

Any plans this weekend? You should make the trip to Perrysburg for the NWOR event on Sunday

Why would you run perrysburg instead of the silver dome?

[Sccabrz192]

Originally Posted by SeanRTR

Why would you run perrysburg instead of the silver dome?

Already committed before DR got off their lazy asses and posted a schedule.


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