NASA SE Time Trials: 2013

[R13]

After running my first TT event back in November, I figure I'd start a thread here for the 2013 season so I'll have a repository for any useful NSX-specific data I come across trying to run a full-ish season this year.

I'm competing in TTB and will be running at venues including Carolina Motorsports Park, Road Atlanta, Roebling Road, and VIR.

For reference when talking about mods, here is the NASA classing chart for TTF-TTB (TTA+ now follow a different criteria).

The NSX base-classes as TTC** (the ** = +14 starting points).

As my car currently sits, I have ~4 points to play with before I hit the ceiling in TTB.

1992 5MT

Weight: ~3030 (including ~162lb driver & ~1/3 tank of gas) although I'm claiming less than this to allow some margin of error with track scales, so I'm taking more points here than I could just to be safely with in the rules.

Corner weights:
LF: 642
RF: 627
LR: 902
RR: 859
(that's 50.5% cross-weight, 41.9%F 58.1%R)

Mods are currently limited to:
Engine:

• ARK DT-S Tailpipe
• Poly F/R motor mounts

Suspension:

• KW Variant 3
• Dali Type Q adjustable swaybars
• Delrin bushings (front only)

Chassis/Brakes

• STMPO front bar
• ABS Update to 2001+

Hawk HP+ pads in OEM calipers
Wheels/Tires

• 17x8 +37F / 18x10 +35R Advan RZ
• 235/40 17F / 275/35 18R Nitto NT05

- - - Updated - - -

Event 1: CMP

Starting 2/9/13.

My last time here I ran a PR of 1:48.690 on 215/255 Dunlop Star Specs. That was in November. The tires are the only thing I've changed at this point. I have a set of headers that I may install in the future, or may sell in favor of some aero.

For reference, the TTB track record is 1:46.05. In November I finished runner-up to a now-banned-from-class Corvette which ran a 1:47.272.

Optimistically, I think 2.7 seconds should be do-able in the car, but that's no margin for error IMO. That 1:48.7 was pushing the limit of how fast I could take the Kink on those tires (I actually spun there the lap after trying to carry a little more speed). I hope to at least match or better my previous best and let the results fall where they do. I don't think I'll be setting any records unless these Nittos are made of pixie-dust, but I do expect improvement.

Video from my last trip to CMP including a nice 110mph spin through the kink (according to phone GPS). The lap before the spin was my PR.
http://www.youtube.com/watch?v=MoQLel7YFAo

 

[DDozier]

Are you running the NT05 or the NT01?

Let me know if you have issues with tire rubbing the front fenders with the 235/40/17's up front, I have to run the 205/40/17 up front and would love to squeez the 235's up there if there is room. I could use more tire to help with braking. I am ready for my second set of NT01's I was very surprised and pleased by the first set, I got 10+ track days on them already and they look like they will take one or two more weekends as long as it is not Putnam Park. They do not have the same grip they had in the first 10-15 heat cycles but they still are hanging in there and I am at 50+ heat cycles. I have never run the Star Specs but others that have run both have told me the NT01's are faster.

Dave

 

[R13]

I've got the NT05s, which are more on par with the Star Specs. The NT01 will definitely be faster than either, but I don't change tires between driving around and racetrack so I need something that will wear a little longer, not heat cycle out as quickly, and deal with water a little better. This will be my first experience with the Nittos. I've run the Dunlops for a couple of years now and loved them, but the set I had on the car was pretty ragged, and they didn't have the sizes left in stock, so I'm experimenting. The NT05s are about $200 cheaper per set, but have had good reviews with track use.

Also, I updated the wheel info with offsets above (since that can make a difference with tire clearance). I can already tell you that the fronts rub on full lock...but really only on FULL lock and even then just barely. I suspect they may not rub at all once they're worn down a bit...it's that close.

 

[R13]

Event 1 Results and Data Dump:

Well, the good news first:

Saturday: 1st Place in TTB! :biggrin:
Sunday: 2nd Place in TTB (to a blown Miata :redface: )

Now the bad news:

Compared to November, I slowed down.

Best lap from November: 1:48.690 // Lap Average from weekend in November: 1:51.458
Best lap from February: 1:49.604 // Lap Average from weekend in February: 1:51.690

Weather conditions were largely similar (cold, dry, typical CMP light breeze both days).

The only thing I changed with my setup was the tires.

My current theory is that the taller/heavier tires added weight and changed the gearing such that I was losing more time on the straights than I gained in the turns having (presumably) more grip.

Compare this video from last year (up to where I spin anyway):
http://www.youtube.com/watch?v=MoQLel7YFAo

To this video from this event:
http://www.youtube.com/watch?v=pLha8tShxJc

I noticed early on that whereas in November I was all over the rev limiter coming into T8 (after the first long straight following start/finish) and again before the kink if I didn't shift, this time around I wasn't even quite to the top of 3rd gear. I'll have some data graphs here in a bit to compare to see if that's what actually happened.

I guess it's time to bolt these headers on, lol.

 

[itrsteve]

Are they running another joint event with VIR for points? I know they did last year at the last minute with the AMP fiasco but haven't been keeping up.

 

[R13]

Are they running another joint event with VIR for points? I know they did last year at the last minute with the AMP fiasco but haven't been keeping up.

VIR is on the SE schedule for October, so it looks like they are.

 

[itrsteve]

VIR is on the SE schedule for October, so it looks like they are.

Oh wow, normally I'm on top of this stuff but the whole NSXPO planning has made me ignore tracking for normal purposes. Interesting that VIR is officially on the map, it hasn't been that way in a long time. Last season was more of a last minute deal.

Also interesting to see that they dropped the typical labor day'ish RRR dates in trade for RA in Sept.

Not to plug NSXPO, but if you're already at VIR for NASA, keep the car there through Tues-Wed that week and run that as well

 

[R13]

Ok, so here's a speed/distance graph of my PR from November vs. my quickest lap from last weekend (Feb).

So clearly, I tip-toed through the Kink (between ~65&71 on x axis), and also appear to lose time through the carousel (Ts5/6/7 between ~25 & 37 x axis)

Also, updated post above with video.

Final update before moving to next event:

About that tire rubbing:

I think a ~+40 offset must be ideal for the fronts to run a 235. The outside edge of the tire rubbed through the plastic fender liner just inside the lip of the wheel well. Ride height probably also played a factor, although my car is far from lowered.

Tire temps:

I took a pyrometer with me and took some measurements throughout the day:
(I don't have "crew" and have limited laps/session, so I couldn't pull in hot to take these. As a result, these are about 1-2 minutes after parking following a cool-down lap)

Session 1: (cold, morning, pressure = 35psi all the way around at the time measurements were taken...so close to "hot" pressure)

RF:
Inside 101
Middle 97
Outside 85

LF:
Inside 98
Middle 96
Outside 92

RR:
Inside 125
Middle 119
Outside 103

LR:
Inside 119
Middle 113
Outside 110


Skipping to Session 3: (~15 degrees warmer ambient, full sun, ~37psi)

RF:
Inside 115
Middle 110
Outside 100

LF:
Inside 119
Middle 119
Outside 112

RR:
Inside 137
Middle 137
Outside 133

LR:
Inside 140
Middle 140
Outside 134

For those who haven't been and/or haven't watch the videos, CMP is a significantly right-handed track, so really the LF/LR numbers are the ones that matter. The Nittos seem to like higher pressure than the Star Specs that I ran previously (which felt happiest ~34-35 hot).

Lastly, my weekend ended by cracking a brake rotor. My first on this car. Thanks to reading a post by I believe CL65Captain at some point, I'd started carrying some take-offs around as spares, so i was able to swap it out in just a few minutes to drive home.

 

[R13]

I'll be down at Road Atlanta this weekend for Round 2. I fully expect to get destroyed by a Civic on hoosiers in my class. His PR is something like 7-8 seconds quicker than mine, and I haven't appreciably changed the car since the last time I was on this track. Hopefully I can pull down a podium, but we shall see. I had intended to put on headers and some brake ducting, but work got in the way as usual....stupid adult responsibilities & crap.

Anyway, if anyone wants to hang out at the track feel free to say "hi". I'm not an instructor, so no passengers, but the more the merrier.

Updates to follow.

 

[R13]

Event 2: Road Atlanta

The Good: I dropped my PR at the track by ~3 seconds
The Bad: That was no-where close to the class leaders this time out. I was barely-not-last on Saturday and last on Sunday

Take-Aways:
-The Nitto NT05s still seemed happiest ~37psi hot or maybe a little higher. That said, I seemed to only have really a three lap window during a session in which I was quickest. I'm not sure if it was tire/car/or driver, but outside of that i was shedding time.
-I was giving up either a lot of horsepower, a lot of weight, and/or a lot of tire to my competition, so everything with a grain of salt at this point.

So, one thing at a time. I did manage a 1:42.599 on Saturday, lap seen here:

That was in spite of some pretty atrocious rev matching going into 10A. I got close, but could do no better the rest of the weekend.

The winning time (in class) was a 1:36.xxx (close to a lap record in-class), so like I said: nowhere close, and exactly as I expected going in.

On balance, I'll take a 3 second improvement having made essentially no changes to the car, and then see about getting closer next time after making some modest changes.

Also, cracked a rear rotor this time. Apparently my car wears rotors out pretty evenly front/rear.

Unfortunately, I hadn't discovered the wonders of data logging the last time I was here, so I don't have any graphs to overlay and see where I made up the time I did. That's ok though because last time didn't involve a concerted effort. I have video of an entire session I'll upload at some point, but if anyone cares to critique based on the short video above, feel free.

Next Round will be either Roebling Road if I can make it work for a 5-day weekend 'cause that's a pretty good haul from Knoxville, or CMP again if not.

 

[R13]

Event 4 (I skipped #3): May 18-19 @ CMP

Prologue

Since my last visit to CMP this year I changed the following:

• Replaced a bad steering wheel bushing so the wheel should be more-often where I left it the previous turn.
• Replaced a bad left rear wheel bearing which I think gave it up after Road Atlanta
• Replaced the cast iron log of an exhaust manifold with stainless steel headers
• Replaced the stock catalytic converters with REALLY LOUD resonated test pipes. I'm glad CMP doesn't have a sound limit. Honestly I'm going to write this off as a learning experience. No cat with a blown-out exhaust and headers = too loud for a dual-use car. I have high-flow cats in the mail currently.

The upshot of the above is I hoped to have a little better car placement this time and about 25 more horses pushing me than last time.


Results

In a word, "Meh".

I placed 4th both days and still could not improve upon my raw time from December.

Racer Excuses:

• It was 20 degrees warmer
• My friend in the 350Z bought Hoosiers
• I ran the December event on Dunlops, and the last two on Nittos....clearly it's the tires
• The vendor was supposed to bring the new pads that I waited too long to order with them to the track, instead they mailed them to my house, so my fronts ended up nearly to the backing plates by the time the event became a washout on Sunday. That was in my head the whole time.

The good news:

• The extra ponies were doing something. The data says my terminal speeds were marginally better.
• I managed to man back up and carry 100+ through the kink for at least a few of the dry sessions. (points 65-77 on horizontal axis below)

Here's a speed/distance graph from the weekend highlighting my quickest lap (S1), my quickest lap that counted (S2), and then my quickest from Sunday (Sun). Tragically I can't really overlay it on the prior times because something changed with the app and there are more datapoints on this one, but I can compare max/min still.

Here's video from the quickest competition session with some slightly laggy data overlay (phone only samples at 1x/second hence the occasional delay in speedo response).

Critique is welcome

<iframe width="853" height="480" src="http://www.youtube.com/embed/-JDhurinq30" frameborder="0" allowfullscreen></iframe>

Take-Aways:

• I still have a steering shimmy. As of this writing I've replaced the right rear toe link (because I already had a new one laying around) although I can't determine that anything was wrong with the old one.
• I really need to order brake pads more than a week in advance (and usually do)...better yet, just have an extra box on-hand.
• No really, Dunlop Z1 > Nitto NT05. My average hot-lap over the entire weekends from the past two CMP events (on WIDER Nittos) has been ~0.5s slower than December (on the Dunlops). Ambient temps were comparable in Feb, and still not exactly hot during the morning sessions this time.