HPDE experiments, results and observations

[rhyary]

Since the 285/30/19 worked so well, I ordered a track tire and will try a PB with 285/30/19 Corsa and 295/30/19 RR. The Corsa is more than I want to spend per tire, So it will be a one time test for this year to help rethink next year strategy.

The Ecsta thread width is the widest among the 285/30/19 and sits on 10.7". All the rest are less and the Corsa is 10.4". So very possible the Corsa will not even polish my inner fenders like the Ecsta P91 does
.
.

[rhyary]

Stats
Date: July 16 2020
Organization: NicksSM3 private day
Track: NYST
Weather: Dry
Track Time: Open track 9-5

Tires Front: Sticker 2019 Ecsta PS91
285/30/19 new day 1

Tires Rear: 2018 Proxa RR
2018 eBay new day 3

Time: 1:37.02 The fastest time on street tires

Comments:
Many many laps on 1:38s. After two laps on 1:37.92 and 1:37.02 it was hard to go below 1:40.

For the rest of the day I was on 1:39-1:40 and here in there dipped into 1:38.

Nick was following me until minute 5:24 in the video. Then I was behind nicksm3 white M3 and we did 1:38.x and 1:40.x. It is the first time I see E92 go below 1:40. Nick were on 295/35/18 square Cup2 and the beauty of 295 showed how easily he negotiates NYST 18 turns. it was wonderful to go together with someone on this forum.

[nicksm3]

That was fun and you drove beautifully!
You should be proud of what you're car is capable of but most of all....be proud of your advancement behind the wheel 👌🏻

[rhyary]

I think I am starting to understand the concept of "heat cycles"

I just finished a second day on the front PS91 285/30/19. The first day I got into the 1:37s and many laps on 1:38.

The second day I was in the high 1:38s in the two sessions, but could get below 1:39s for the rest of the day despite the fact I had clear track.

If you look at the front tires, there is plenty of tread left. Finally after stiffening the car and putting camber on -3.5, I no longer peel the rubber of the carcass. So I am not on the cords, but I am no longer fast as the first day.

Perhaps this is also how tires are different from each other. Not by how you consume the rubber, but how you consume the speed of the tires.

I have variety if front tires in inventory and assuming that all if them can go 14 x 20min at NYST, it will be interesting to see what happens the second day.

I am happy with the rear 295/30/19 Proxes RR. Since I am now running mostly with DSC=off, I can fill that on the fourth day my rear is moving around, but it slides in a predictable/catchable way to is enjoyable to experience, but is also not as fast. Overall, I think the rear has less importance to lap time than the front, up to a point.

Picture of PS91 after two trackdays. Nice even wear:
.

[dparm]

*Proxes, not Proxa

You can see the effects of heat cycles if you look at peak G in the data (lateral and longitudinal). The max values will slowly creep down over the tire's life, all else being equal.

[rhyary]

Originally Posted by dparm

*Proxes, not Proxa

You can see the effects of heat cycles if you look at peak G in the data (lateral and longitudinal). The max values will slowly creep down over the tire's life, all else being equal.

Noted. Fixed. Proxes.

Data should confirm the laptime. Will check later

[rhyary]

Since my next trackday is Aug 14th, there is not much laptime updates. However, here is some maintenance update.

The experiment of the front PS91 285/30/19 was a huge success. The 240 tread tire did great and survived 2 days at NYST with tread left. It is no longer fast, but getting to 1:37.02 is showing that width matters.

I now have Pirelli Corsa 285/30/19 60 tread tire ready for Aug 14th.

While I wait, the JRZs are sent to Tim Olsen for rebuilt. The front passenger had oil leaking when I got home from the last trackday. It only start leaking after it was two days on the QuickJack and then when I lowered it down the oil came out from the top.

Tim updated me on the status late Friday. The adjusters on the rears are not doing anything. Hmm strange. The teardown is scheduled for Monday and beyond the normal rebuild (seals) will see what else.

I originally wanted to re-valve to 20% stiffer as I was on the upper end of the adjusters. But now this thought is on hold.

The moving from 900 rear to 1000 rear spring is still happening. Perhaps the rears could not take the 900.

The thought that I did 1:37.02 on only "springs" no dampers, is kind of interesting.

I did notice my car was too soft at the 100mph slalom 8-9-10 at NYST and I kept "adjusting" the JRZs to stiffer and stiffer.

The interesting part of this is that when I adjusted to a click stiffer, it felt stiffer but then it felt softer as I was driving it to and from the track. I attributed this to "I am just getting used to the car being stiffer". Hmm I guess not everything is in my head after all.

Back to tires. The Corsa were cheaper than Hoosier and 20mm wider. This is the first full priced tires I bought this year, but I had to know what 285 Street&Competition tire can do.

To compensate for my indulgent, I got a 285/30/19 GY F1 Asym 3 on sale at TR for $142 a tire.


At this point I have tried all these sizes on my front:
235/35/19
265/30/19
265/35/19
275/30/19
285/30/19

[rhyary]

Stats
Date: Aug 14 2020
Organization: Got Track Li
Track: NYST
Weather: Dry
Track Time: 6 x 20min, last hour open track

Tires
Front: Sticker 2020 Pirelli Corsa 60 Tread Street and Completion. Tire Rack
285/30/19, new day 1

Rear: Sticker 2018 Proxa RR eBay
295/30/19 , new day 1

Time: 1:37.05
DSC=off
3/10th slower than the The fastest time on half the price PS91.

Tire got destroyed after 5x20min session.

I am pissed about paying for full priced tire that got no results. I was hoping to get into 1:36 or even 1:35.

Comments:
I got the front JRZ back from rebuilding and I started to soft HS=8, LS=6, R=15, shaft=15

Since the rear where not ready, ACM put used Ohlin RT they had laying around on the rear as a place holder. Since went from 900 rear to 1000 spring, how the RT was controlling the 1000 had unknown quality and non adjustable.

The 1:37.05 was done when the front was too soft and car unstable, especially with DSC=off.

I adjusted the front to HS=12, LS=5, R=16, shaft 16 and the car returned to its stable state, but the Corsa dropped off and I switched to my other front set 265/35/19 RE 050A 140 tread tire.

On the RE 050A i was stable on 1:40 and occasionally doing 1:39.

So far the PS91 285/30/19 not only had the best time with multiple 1:37 and 1:38, it also had the fastest time on street tires over 3 years of experimenting with tires. To boot, it is still good after 2 full track day (14x20min session)

pic of Corsa after 5 sessions

[dparm]

Wait, the Proxes RR was slower than a PS91? No way.

That Proxes should be 3-4 seconds faster when new, maybe 2-3 seconds faster with lots of heat cycles on it.

[Bartledoo]

So mismatched coilovers and mismatched tires concurrently? That's an interesting test lol.

[rhyary]

Originally Posted by dparm

Wait, the Proxes RR was slower than a PS91? No way.

That Proxes should be 3-4 seconds faster when new, maybe 2-3 seconds faster with lots of heat cycles on it.

Proxes in the rear on both days
The fronts were different

I am very happy with the Proxes RR 295/30/19 on the rear. Most of my experiments are focused on the front tires

[rhyary]

Originally Posted by Bartledoo

So mismatched coilovers and mismatched tires concurrently? That's an interesting test lol.

Where do you see mismatched coilovers?
I don't have coilovers in the back.

[Bartledoo]

Originally Posted by rhyary

Where do you see mismatched coilovers?
I don't have coilovers in the back.

Thought you had jrz on one end and ohlins on the other?

[dparm]

Originally Posted by rhyary

Proxes in the rear on both days
The fronts were different

I am very happy with the Proxes RR 295/30/19 on the rear. Most of my experiments are focused on the front tires

Have you run RR all around? It's a very capable tire and the price is pretty good for what you get.

[rhyary]

Originally Posted by dparm

Have you run RR all around? It's a very capable tire and the price is pretty good for what you get.

I did. but front I can only get 235/35/19.
It was fast, 1:37 many laps, but it looked funny :-(

[rhyary]

Originally Posted by Bartledoo

Thought you had jrz on one end and ohlins on the other?

Yes.
The rears are divorced setup.

Once I stiffened the front it was manageable.

Not ideal, but I am not giving up a trackday for symmetry.

It will be better when the rears are returned from rebuilt.

[dparm]

Originally Posted by rhyary

I did. but front I can only get 235/35/19.
It was fast, 1:37 many laps, but it looked funny :-(

Why not do a 275/35R18 on the front or something like that? It's odd they don't make something more intermediate in 19".

[Bartledoo]

Originally Posted by rhyary

Yes.
The rears are divorced setup.

Once I stiffened the front it was manageable.

Not ideal, but I am not giving up a trackday for symmetry.

It will be better when the rears are returned from rebuilt.

Yea, I just didn't feel like typing the extra words in place of "coilovers".

Just bustin your chops though. Better to be on track than not at all. I just realized that I've done several track days with loose front shocks, so not any better!

[ThunderMoose]

Originally Posted by dparm

Why not do a 275/35R18 on the front or something like that? It's odd they don't make something more intermediate in 19".

18's won't clear his brakes

[dparm]

Originally Posted by ThunderMoose

18's won't clear his brakes

Jeez, how big are the rotors? An 18" Forgeline will clear 394mm CCBs.

[rhyary]

Originally Posted by dparm

Jeez, how big are the rotors? An 18" Forgeline will clear 394mm CCBs.

An 18" Forgeline gives me 3mm clearance. I opted for 19" as my third set. I don't want 3mm clearance. My car is not a show car.

[rhyary]

Just finish a day at LRP.

First part of the day was Car Clinic Control. The CCC is divided into 3 groups 2 Auto-X tracks and one skid pad. I got to slide around, counter steer and played around with oversteer as much as I could.

In the afternoon I had the norma 4 x 25min sessions.

I used 295/30/19 2013 Yoko V105 on the rear and 265/30/19 RE 050A. Both tires were first for me.

The CCC was fine, mostly understeer and oversteer induced by throttle.

Coming to 1pm big track, first session, it was terrible. Car was oversteering like crazy at 1:10 pace. I felt really uncomfortable.

Coming off the first session, the tires were @ 38 psi hot. This is typically what I run at NYST. Took temp and they were at 130f, some how I did not get them hot.

Rather than mess up with the suspension, I opted to reduce tire pressure. went for 35 psi hot all corners.

Second session was much better clocking 1:05s and feeling better. off second session tired went up to shy of 37psi

Took the down to 35psi hot and went to third session. Much better. clocked 1:05 most of the laps.

Fourth session I left it along and was about the same pace.

This is not hot pace, I was much more comfortable last time I was at LRP doing 1:01 and feeling good on Rear RR and front Hoosier take off.

But given the situation, new spring in the rear, unknown shock in the rear, 2013 rear tire I was not going to push it beyond 1:05

My last two sessions were with DSC=off and the car as good as it gets at the risk level I am willing to take.

Next week I am going to Palmer Motorsport, a new track to me. So just going in intermediate group, same tires, with the PS91 285/30/19 for front backup.