Thunderhill Track Day Recap 7/10

[Sylvan]

So I went to Thunderhill on Sunday. It was a nice day, pretty mild in the morning but about 92 degrees in the afternoon. I was in the Solo group with Norcal racing club (NCRC). I think it was my 7th track day overall. My car is a bone stock 94 5-speed.

As discussed in another thread, I was having some questions about my Kumho XS street tires and still working on dialing in some good pressures for maximum grip. Today I started out by bleeding down to 30 front / 31 rear cold, and by the end of the first session they were at 36 / 37 hot. They felt great, really grippy, and just a hint of oversteer when pushed too hard, but it was easily correctable. There were no surprises or snap oversteer. I think I finally have the tires where I want them. I picked up a few mph in Turn 2, the long sweeper. I can now take that at 70 mph where before I was feeling limited at around 65 mph. I was also hitting the rev limiter before then end of the front straight a little bit earlier than before, so I was carrying more speed in Turns 14 and 15.

I felt more confident in Turn 7 but I still couldn't handle Turn 8 flat out. I had to let off and tap the brakes briefly just for my own sanity. I don't have the balls to push that turn too hard because it is very fast, and I would hate to go wide on that turn.

I was significantly faster this day than I was on my previous day out. Last time, I was getting lap times around 2:28 - 2:30ish. I don't have a lap timer so I have to use a stopwatch on my videos, so it's approximate. But this time I recorded 2:14 which is a big improvement (Turn 5 bypass). I had a lot of traffic to deal with so I didn't get many clean laps. But I was passing most cars, I only pointed by a couple of cars.

The suspension was working pretty hard, it felt like. I guess 110k old stuff is just tired, but it all held up OK. I met another NSX owner (Rami?), he was a cool guy who unfortunately had mechanical issues and couldn't finish the day. Towards the end of the day, there was a Civic that rolled out in the dirt after Turn 6. The carnage wasn't too bad, and the driver was OK. I wanted to take a pic of the aftermath but it felt kinda morbid so I didn't. With some more seat time I'm sure I can keep improving. There may be a few more seconds left in the car as it is set up right now. I don't know how much more I can improve without making modifications but we'll see!

I got a couple of pics from Dito at www.gotbluemilk.com. I like this one because my right side is compressed so it looks like I have lowering springs.


This one shows some of that major sidewall compression on that right rear tire.


I'll post up a video after I get it edited.

 

[Hrant]

.... Today I started out by bleeding down to 30 front / 31 rear cold, and by the end of the first session they were at 36 / 37 hot. They felt great, really grippy, and just a hint of oversteer when pushed too hard, but it was easily correctable. There were no surprises or snap oversteer. I think I finally have the tires where I want them. ...

Glad it worked out for you ..... But if you recall, I did take pains to note that with those tire pressures you will indeed get oversteer with street tires - and this is at your level where the car is not pushed to its limits. And trust me, 2:14 is good but you still have a few more seconds to shave with stock set-up albeit not with those tire pressures where the oversteer will be more like 360 with NO time to correct or recover. Your second picture is pleading for some track sway bars:wink:

 

[Hrant]

duplicate

 

[stuntman]

Glad it worked out for you ..... But if you recall, I did take pains to note that with those tire pressures you will indeed get oversteer with street tires - and this is at your level where the car is not pushed to its limits. And trust me, 2:14 is good but you still have a few more seconds to shave with stock set-up albeit not with those tire pressures where the oversteer will be more like 360 with NO time to correct or recover. Your second picture is pleading for some track sway bars:wink:

And I have said many times that those pressures are close to ideal ;-)

 

[Sylvan]

Ok let's not get into that debate again

It was a fun day, hopefully I'll get the videos up soon. By the way I hope the other NSX guy chimes in and gives us an update on how his car is doing.

 

[mochanges]

Hey Sylvan,

It was great meeting you, I knew you would be there since I had read your previous post. It's Jami (pronounced like Tommy with a J) but no big deal, most people have a hard time with my name.

I had a rough day, my first session started with me spinning on lap 1 of session 1 coming into turn 3. I hadn't realized how much it drops off and how hard it turns right and I spun into the dirt. That put me into the wrong mindset for the rest of the session but I was looking forward to recovering the rest of the day. Unfortunately my coolant tank cracked and I spent the rest of the day hanging with friends and getting it patched up so I could drive home. I made it home no problem and will replace the coolant tank soon.

I timed you during session 4 and also had you around 2:14 for your best lap, my buddy in the 350Z (who you passed) was putting down similar times in the same session (2:14-15). You were pretty darn fast and my friends had a hard time believing it was the same driver/NSX we had watched the night before on YouTube!

Even though I had basically no seat time it was still fun and I'll be back to try Thunderhill again.

 

[Sylvan]

Hey Jami (sorry!)

I'm glad you were able to make it home OK. Hopefully you'll be back on track in no time. I'll probably head out to Thunderhill again in August. I was actually watching someone else's video from Sunday, and through her car I saw you off in the dirt past Turn 3!

That's cool that you stuck around and managed to time some of my laps. The thing with my videos is, for some reason they just don't convey the sense of speed very well, so it's hard to judge how fast it "feels" by watching the video. I felt like I was flying, but the video is pretty ho-hum. Oh well. Any video experts have recommendations for making the videos "feel" faster?

 

[2slow2speed]

Sylvan,

Tapping the brakes before the turn in point of turn 8 is the right way to go because you want to be accelerating when hitting the apex at turn 8 to keep the rear end of the car planted as you track out. Some folks will just lift before the turn in point before getting on the gas but that takes a bit to get used to it. 2:14 with the bypass is comparable to 2:16 with the cyclone at turn 5, really good lap time considering the age of the suspension of your car and the fact that you are running street tires.

36/37 PSI hot sounds about right in regards to tire pressures. If you have access to pictures from Ditto take a look at the various pictures like the ones that he takes around 14-15 to see how well the suspension is working when the load is placed on the outside tires when hitting the apex.

As far as the sensation of speed on videos just having a good sound source will add to the sensation of speed by listening to the engine/exhaust note as well as listening to the tires screeching for mercy

 

[2slow2speed]

Btw: a cheap lap timer is Harrys Laptimer on the iPhone/iPod touch + a tomtom gps cradle if you already happen to own an apple product.

 

[Sylvan]

Sylvan,

Tapping the brakes before the turn in point of turn 8 is the right way to go because you want to be accelerating when hitting the apex at turn 8 to keep the rear end of the car planted as you track out. Some folks will just lift before the turn in point before getting on the gas but that takes a bit to get used to it. 2:14 with the bypass is comparable to 2:16 with the cyclone at turn 5, really good lap time considering the age of the suspension of your car and the fact that you are running street tires.

36/37 PSI hot sounds about right in regards to tire pressures. If you have access to pictures from Ditto take a look at the various pictures like the ones that he takes around 14-15 to see how well the suspension is working when the load is placed on the outside tires when hitting the apex.

As far as the sensation of speed on videos just having a good sound source will add to the sensation of speed by listening to the engine/exhaust note as well as listening to the tires screeching for mercy

Thanks for the input. I agree on Turn 8, it feels a lot more stable and comfortable to be under acceleration to keep weight on the rear. It's just that one of the instructors was saying that you can actually take that turn flat out, you just have to work up to it. He may have been referring to cars with less power / more grip.

Oh and thanks for the tip about Harry's lap timer. I'll check it out before next time.

 

[Racer NSX]

Turn 8 might be able to be taken flat out on street tires on an NSX, I would not recommend it. If you go wide at turn 8 and into the dirt, you will be for a really rough ride and most like damage you car at speed. With the right suspension and R-comp tires, the car is capable of taking 8 flat out but the driver might not be up to it. With a worn suspension and regular street tires, I would play it safe and tap the brakes on entry to turn 8.

 

[Track Addict]

Turn 8 at T-Hill is a fun one that if you have cleared 6 and 7 correctly you have a ton of speed carried into the entry of 8. I PARTIALLY lift at entry (due to being on street tires mostly). I've got flat in other cars through 8, but not yet with the X.

Turn 9 there is a ton of time to be found if you are willing to keep your foot in it, just sayin'

I really enjoy running T-Hill backwards, from the top of 9 to the entry of 5 is flat out and downhill, that's an intense ride. (NASA runs T-Hill backwards every so often)

edit: I can't stand the point by, personally. NASA is great for that.

 

[mochanges]

Hey Jami (sorry!)

I'm glad you were able to make it home OK. Hopefully you'll be back on track in no time. I'll probably head out to Thunderhill again in August. I was actually watching someone else's video from Sunday, and through her car I saw you off in the dirt past Turn 3!

That's cool that you stuck around and managed to time some of my laps. The thing with my videos is, for some reason they just don't convey the sense of speed very well, so it's hard to judge how fast it "feels" by watching the video. I felt like I was flying, but the video is pretty ho-hum. Oh well. Any video experts have recommendations for making the videos "feel" faster?

Did this video you mention get posted to YouTube? I'd love to see the spin.

 

[92 white 0650]

Re: Gotta love it.

Congrats on a huge improvement; you're on a very steep learning curve. At 2:14 in your equipment and at your level, I'd creep up on improvement at this point and work on consistency, focus and keeping it within inches of the line.

And easy on Turn 8; it's the fastest corner, and because of the speed, it is arguably the worst place for an off. Regardless of what you hear around the lunch table, very, very few cars are flat thru 8. And the ones who are, at least in race class, don't have doors or roofs.

 

[2slow2speed]

I really enjoy running T-Hill backwards, from the top of 9 to the entry of 5 is flat out and downhill, that's an intense ride. (NASA runs T-Hill backwards every so often)

edit: I can't stand the point by, personally. NASA is great for that.

FWIW, Just making sure that the NSX folks are not misinformed, there is no way in hell that you can drive between 9 to 5 flat out on a NSX when running THill backwards, 8 is real turn so are turns 7 and 6 when you are carrying speed. On a car with low HP and a lot of grip like a spec miata it might be possible, on a NSX you will go off track on 8, 7, 6 and even before you hit 5 if you are driving flat out it simply can't be done.

 

[Hrant]

FWIW, Just making sure that the NSX folks are not misinformed, there is no way in hell that you can drive between 9 to 5 flat out on a NSX when running THill backwards, 8 is real turn so are turns 7 and 6 when you are carrying speed. On a car with low HP and a lot of grip like a spec miata it might be possible, on a NSX you will go off track on 8, 7, 6 and even before you hit 5 if you are driving flat out it simply can't be done.

Ken, I am glad you called this spade by its name. I was holding back real hard swallowing yet another barrage of bravado on commenting on such frightening assertion. It's one thing to talk smack at the track and something quite different to post on a forum. Going backwards at 8 is a real challenge since there is literally no margin of error at track out (counterclockwise they added extra 4ft of pavement). Same with 6; no margin for error.

But then again, what do we know; we are old school old farts as Tedro would call us :wink:

 

[Sylvan]

Thanks guys for keeping it real. I like hearing from folks who have real experience on the track so that I have an idea what I can expect in my car. I've never run Thill backwards but I would imagine that it would be even faster down the back of 9 through 8 and 7 because of the downhill section, so even more caution would be warranted.

Anyway I finally got a video uploaded of my 4th session. Looking back I can see that I'm still kind of searching for the right lines through some of the corners, and still lacking some real consistency. Still getting used to the manners of the car. As I mentioned there was quite a bit of traffic in some spots. There were a couple yellow S2000s that day that were quite slow and not very quick to point cars by. Nothing against S2000s, but I don't know if these guys in particular were taking it seriously. I did have some clean laps in the middle I think. I'd appreciate some tips on where I might find some lost time or room for improvement.

<iframe src="http://www.youtube.com/embed/X4I7Sy7KF2E" allowfullscreen="" width="853" frameborder="0" height="510"></iframe>

 

[Sylvan]

Did this video you mention get posted to YouTube? I'd love to see the spin.

Yea, search for "thunderhill 7-10-11" and click on Diane's 1st session link.

 

[mochanges]

Thanks Sylvan.

 

[Hrant]

Sylvan, my $0.02 after my second coffee and watching 2/3 of your video.

First, for this being your 7th track day, you are doing quite well! You have a good knack of track/speed.

I didn't notice any oversteer, except for turn 5 bypass once - more on this later, but perhaps more subtle understeer and this is probably due to some early apexing at some of the corners like 6 (no margin there if you drop 2 and many of us have), occasionally at 8 where you are way into the berm at trackout, and most definitely at 14 wher you are cheating royally by going way over the track out berm (same cheating at 11-12) :wink:

For turn 1, if you take the apex just a car length later, you will be able to throttle through the apex more aggressively and not fear of losing pavement at track out; that speed carries you all the way to the enry of 2.

For turn 2, you are cutting/hugging the inside a bit too early (with slick tires that may be ok); start from far right, get to the middle of the track about 1/3 into the turn and by just about mid point as you start seeing the apex start feeding throttle to open the turn as you late apex at full throttle.

For the bypass, you are too close to the right and that is why the car is loose unsettled when you come off the blind crest. It will feel loose anyway but less so if you land in the middle of the turn after the crest so the bottom of turn 5 to 6 will give you more of a straight line throttle. So start a bit to the left or dead center entering the crest but don't hold the steering too much cranked to land too far on the right after the crest.

Lastly, you really don't need to shift and be on 2nd from 3-6; not even on 9. You have a tall 3rd gear if it is OEM but those with 6 definitely hit 4th before 9 as we ran out of RPMs, before 10, before 14, and on the front just 1/3 before the flag station.

But overall this is good and reassuring; we now have another track junky in NorCal :tongue:

 

[Sylvan]

Hrant,

Thanks for the detailed analysis, and for the compliment :redface: I think you are spot on when you talk about apexing a little later, because I do sometimes feel like I'm about to run out of track, particularly Turn 1 and Turn 8. I'll try a later apex and see how that works.

Turn 2 sounds good, I'll try to start from the right more and slowly bring it in.

Unfortunately the next time I will go is going to be the cyclone configuration, so I won't get to play with the bypass crest on Turn 5.

Were you really saying I could just leave it in 3rd gear after Turn 2, and stay in 3rd until Turn 6? Or even through Turn 6? (5-speed car). I can try Turn 9. I might be slowing down more than necessary just so I can stick it in 2nd gear, but then I change back to 3rd right after the top of the hill, so I don't know if that gear change is really necessary.

I'll try not to go so wide on 14 :wink:

 

[Hrant]

Yep stay on 3rd from turn 2 through 6 if you are doing the bypass. But if you do the cyclone, just before the turn go to second and by the time you are at the bottom, you may need to shift to 3rd or carry 2nd by bouncing off the rev limiter - which will force you to 3rd at 6th track out and that is not a good spot to load the car with a gear change. So short shifting is helpful.

For us with 6 speed, we hit the rev limiter on 3rd before 8; I choose to lift rather than go 4th .... And Ted is right on, taking 8th flat out is a huge challenge. I have come close but no cigar when I am close to 3 digits; I do tap the brake to get more turn in bite! For 9, really going to 2nd is not needed; but to take advantage of that additional speed with 3rd, you may need to adjust your turn it for at trackout you are already at the berm after the crest. Play with half car length adjustments with your apexing - ie take it a bit later and then scale back as turn 9 like early entry but you must be able to rotate the car.

On 2nd in VTEC close to redline at most turns, the NSX is a bit too wound up edgy/itchy which makes the throttle inputs more difficult if you want to power through or open the turn more

And one last suggestion, unless you need to be sitting that far back for head room, bring the back up a bit. Your hands were stretching at steering. That additional flexibility at the elbow makes it more comfortable and smooth. But your steering was smooth, no jerky movements. Just ask hot shoe Steve when I had to steer for him LOL!

Edit: By the way, since you were running quite a bit on 2nd close to 7K RPMs, what was your temp showing? Still in the middle? At 92F ambient temp, quite a few of us have had overheating.

 

[Sylvan]

Edit: By the way, since you were running quite a bit on 2nd close to 7K RPMs, what was your temp showing? Still in the middle? At 92F ambient temp, quite a few of us have had overheating.

At or slightly below the middle of the gauge most of the time. Near the end of the day, it was creeping up just past halfway at some parts of the track. Maybe if I spend more time in 3rd it will be easier on the car. It just feels dog slow in 3rd at 4-5k RPM compared to being in 2nd at 6-8k RPM and then shifting to 3rd later on, but maybe it's just a mental thing. It might not be any slower after factoring in smoother steering, fewer gear changes, etc.

What's your take on left-foot braking? Do you use it to slow you down on turns where you know you are not going to be downshifting?

 

[2slow2speed]

Sylvan,

Really nice driving!

Hrant's comments on Turn 5 are spot on, that is the one area that I thought that needed the most improvement.

Making use of the most of the inside berm on the apex of turn 12 and going over the outside berm between 14 and 15 is the fastest line through there so as long as they don't have any cones to block the area, it's all good Just remember that if you ever do a track day in the wet you will want to avoid the painted surfaces so you will more than likely revert back to what used to be the late apex classic line entering 11 and 14 as well as the one at turn 8.

In regards to Hrant's comments about the early turn in at other areas of the track. It all has to do with how fast the car is going through the turn and wether or not the car is at the limit of adhesion and is slipping/drifting through the apex or not. It is kind of hard to explain to people who have not experienced it before, but from your video it seems that you are already doing it at some turns like turn 11.

The attached video is from one that I took at Thunderhill on Tuesday that might provide a reference as far as the line goes for your next track event with the Cyclone. It should also give you an idea about the changes in the turn in point once you get the car to be on a slip/drift before hitting the apex.

<iframe width="560" height="349" src="http://www.youtube.com/embed/oMn4riZdKQo" frameborder="0" allowfullscreen></iframe>

 

[2slow2speed]

Anyway I finally got a video uploaded of my 4th session. Looking back I can see that I'm still kind of searching for the right lines through some of the corners, and still lacking some real consistency. Still getting used to the manners of the car. As I mentioned there was quite a bit of traffic in some spots. There were a couple yellow S2000s that day that were quite slow and not very quick to point cars by. Nothing against S2000s, but I don't know if these guys in particular were taking it seriously. I did have some clean laps in the middle I think. I'd appreciate some tips on where I might find some lost time or room for improvement.

BTW: Your 2:14 laptime with the bypass is a pretty good one, you are already pushing the car quite a bit even if you don't realize it.

Work on consistency for now, and as Billy commented on the other thread, making sure that all of your NSX components are up to the task before pushing the car harder makes a lot of sense (that also include maintainance bits like brake piston seals, brake lines, coolant hoses, thermostat, etc, etc)

Thanks for the information. As I mentioned, I've only done 6 track days so I'm relatively inexperienced. That's why I wasn't sure what constitutes too much sidewall flex. From the looks of it, and what you say, I guess I don't have anything to worry about. I'll keep playing with the tire pressures a bit to see if I can get an optimum setup.

As far as my alignment goes, it's within factory spec, but I might see if I can dial in a bit more negative camber.

Sway bars sound like a good idea but I'm still at a mental cross roads if I want to do any modifications at all to the car. I'm not doing competitions so I don't yet see the point in doing mods. That's kind of a philosophical debate with me, because I think at this point I want to learn how to drive well and quickly with my car as it is. Mods might make me faster but then it's kind of a crutch. So I might pass more cars, but a modified car passing a stock car doesn't really say much about the driver or the car, except who has put more money into their setup. Like if a (supposedly) inferior car passes me in some turns, then later in the paddock I check him out and he has Hoosiers and coilovers, then I don't feel bad because it was just his $$ that was faster than me, not necessarily his skill or his car's ability. Anyway, that's a whole other discussion in itself, and I'm still going back and forth on mods. I may end up doing some suspension upgrades for next year's track season, after at least a year of stock driving under my belt.

Anyways, thanks for the input. I'll be out there next Sunday tweaking some more and having more fun

I don't really agree with this but its your car and what you're looking to do with it. Improving the stability of a 20yo car that wasn't designed with the types of tires you have on there now, with springs and shocks that are probably worn out and not up to par to what it was when new, and swaybar bushings that are worn out and allow for more body roll than when new - replacing them or upgrading them to improve the stability and balance to match todays modern tires and make the car easier and safer to drive and learn how to push the limits of a car to improve your driving is hardly a crutch.

IMO I don't think upgrading the swaybars, wheel spacers (or wheels), or even going to a coilover suspension is a crutch. I would say this is less so than going to R-compound tires or slicks, or adding more power. I still say improve the handling of the car so it dosn't have a mis-match balance for the grip levels and speed your driving it.

0.02