HPDE experiments, results and observations

[rhyary]

so by 3pm I exhausted all my ideas on how to get traction on the back.

Since I always bring with me 2 front tires I decided to mount than on the rear.

so on goes RE-71R 265/35/19 on the rear.
these tires had some track time on the front.

What difference.
Car felt great.
It still had DWS all season on the front, but now I had traction on the rear.

So from 4-5pm was open track.
And the drizzle finally stopped, and the track was drying out.

I stayed our for full tank.
40 laps on 63-64 seconds. ~55 minutes

The day ended up terrifically

So for the record, it is possible to have lots of fun with 265/35/19 on the rear and 285/30/19 on the front and totally mismatch tires and types.

First time with the Zeb splitter and it felt very good. Hard to know exactly what it does, but the front felt good.

[dparm]

Originally Posted by rhyary

Hard to know exactly what it does, but the front felt good.

Balances the aero and helps the car turn in, lol.

[rhyary]

The data from BMW PT6 Test3 ECU were very good.
in this test ECU from AIM we increased the sampling options on many PT6 variables to 25Hz and 50Hz in addition to 10Hz.

The added sampling rates will help with the deriv() function and will make it more detailed. The deriv() function take a variable like steering angle, brake press, wheel spd and converting the value to rate, or velocity.

For example Steering Angle tells you how much the steering wheel was turn. For that, 10Hz is probably enough sampling. 10Hz = 10 times per second

But if I want to know how fast the driver turn the steering wheel, to see oversteering correction, or how smooth the driver is, then I want to see deriv(steering angle). And for that I want to sample it at 25Hz.

I sent AIM Support my data file from Saturday. Once they confirm my data, I expect a new production PT6 ECU to be available via the normal download in RS3A.

[Bartledoo]

Originally Posted by rhyary

But if I want to know how fast the driver turn the steering wheel, to see oversteering correction, or how smooth the driver is, then I want to see deriv(steering angle). And for that I want to sample it at 25Hz.

Have to correct you here. Steering wheel angular velocity does not tell you how smooth a driver is in the context of performance driving at the limit. Driving smoothness is incorrectly interpreted in this manner so often. If this was the case then the slowest driver could be the “smoothest”, rendering smoothness a non-performance characteristic. However, if you are driving below the limits of the tires, then yes smoothness can be indicated by steering wheel velocity, but what is the point in that?

“Smoothness” in this context relates to the transition of weight transfer, lateral and longitudinal loading of the car, yaw, etc. Being smooth can actually involve small but fast steering inputs.

[rhyary]

>> longitudinal loading of the car, yaw, etc. Being smooth can actually involve small but fast steering inputs.

I was not clear.
My point about asking AIM to increase the sampling rate was to be able to see "small but fast" steering input. I did not mean to out value on driving smooth.

To your point, if "smooth" is or isn't desirable, than I want to see it and 10Hz may not have enough sampling rate.

[dparm]

I use the derivative of various driver inputs to track "aggressiveness". Sawing at the wheel does not imply you are fast, nor does being butter-smooth. Being at the limit of traction and making micro-corrections is how you keep the car at the limit.

[rhyary]

Just a quick update before a full send on 4/2 at PMP CCW with MassTuning.

I did LRP 9am-12pm Car Clinic Control at the upper deck with SCDA and it was awesome. Dry conditions. The new repaved Auto Cross is fabulous.

Did upper first and lower next and this happens.
Lost the sway bar link. added a washer at home and back in business.

On the big track 1pm-5pm coached an F80 M3. It was raining from 1-5pm. We worked on throttle and brake timing. I used the new RS3A to sync video and data and it worked well. Looking at the data and jumping to movie screen to see where. Student had Solo2DL and Smartycam Setup and it allowed for efficient review.

It was nice to not worry about my driving. I waited with the laptop and soon as student pulled in I downloaded the data via WiFi, and by the time he got out of the car and handed over the Smartycam SD card the Solo2DL downloaded was completed and I downloaded the Smarty SD.

It was cold and rainy, but LRP is such a nice facility. We went into the classroom at the tower and were able to review data in a warm classroom and out of the rain.

I also took the F80 M3 out in the advance group and was not happy with the traction. Yes it was rainy and cold, but still I think the choice of tire allowed the rear to come around too easily and cemented my dislike to the 265/35/19 front and rear 295/30/19 tire size selection. The Goodyear F1 Super Sport are good tires, but after seeing few trackdays last year were not a good idea for a cold rainy spring north east early spring day.

Anyway. I am of the opinion that a 265/35/19 275/35/19 or 265/35 305/30 works better.

Picture of the sway bar link and fixed with a washer:
.

[rhyary]

Zebulon 70" wing installed.
Ready for Palmer Motorsport CCW with Masstune on Saturday

Tires
UHP All season Dunlop Signature HP
265/35/19 front
275/35/19 Rear

Weather Forecast
36* morning
50* afternoon

[Bartledoo]

Originally Posted by rhyary

Zebulon 70" wing installed.
Ready for Palmer Motorsport CCW with Masstune on Saturday

Tires
UHP All season Dunlop Signature HP
265/35/19 front
275/35/19 Rear

Weather Forecast
36* morning
50* afternoon

All season again?! Bruh you’re crazy.

Nice track conditions though.

[rhyary]

Originally Posted by Bartledoo

All season again?! Bruh you're crazy.

Nice track conditions though.

Yeh I know.
It will be Sunny.
I wanted to give the all season 275/35 265/35 a chance.

The 305/35 and 285/30 only worked for the front. We can say it was because the 305 was Cooper and blame it on the tire. But I think the real reason is that in cold and wet conditions, or just cold, I can't get heat into the rear.

In fact, the only time I was able to get heat into a 305/30 is on Watkins Glenn.

So while I don't expect miracles from all season, it should be good heading to PMP in 32*, first part of the day at 40* should also be good.

The afternoon at 50* I may mount on the front the RE-71R (I can only bring two spare wheels so I always being two fronts that also fit the rear)

Will see. It is mainly a day to collect data points

[rhyary]

Palmer Motorsport day was a success.
Sunny day started with 35deg and warmed up to hight 40* in the afternoon.

The Dunlop HP UHP All season was a success.
Car felt great on all 7 sessions.
It was not fast, but consistent.
I was able to run 1:56 most laps with 1:55 here and there.

The most important to me was how it predictably lost grip front or rear depending on what I tried. And it was well balanced.

I am not used to be the slower guy at the advanced group, but considering everyone else was on slicks or track tire of the 100tw or 200tw variety I held my own fine.

My conclusion os that UHP All season on cold and or wet days is a legitimate way to test your car on early North East trackdays. You have to be willing to be slower, and the fun is in finding away to drive the car and maximize grip.

This kind of tire also allows you to simulate wet driving on a dry day to some degree. It does not replicate the unpredictability of rain on the track, but it is close to wet track with no water pooling on it.

So, in short this met my expectation for $130/tire
265/35/19 front ($125)
275/35/19 rear ($130)

265/35R-19 DUNLOP SIGNATURE HP 2018 PRODUCTION SL

275/35R-19 DUNLOP SIGNATURE HP SL

[DoubleYellow]

Great track day at PMP, no crowding in advanced run group, generous point bys. Dropped over 6 seconds with new MCS suspension and better late braking. I'm on MCS 2WNR, NT01 and ST BBK, otherwise stock. Optimal lap is 1:48.xx so need to improve consistency.



@rhyary your aero looked cool in person. Nice chatting with you.

[rhyary]

New springs in the spring.

This a bit complicated to explain but I'll try.

Last year, before the season started, I installed a stiffer rear spring 1100 up from 1000. It is a divorced setup so you don't get a true up of 200.

I went testing it with a rear 305/30/19 tire. Keep in mind that testing in March and April means cold temp.

I had terrible time with oversteer. Finally, I gave up and went back to 1000.

Unbeknown to me, I had a broken compression shim on the front, and broken rebound shim in the rear.

Now, for this season I started with rebuilt JRZs, 750 front spring (been there for 4 years) and 1000 rear.

When I went to LRP with a 305/30/19 all season I had a terrible oversteer. So now my theory is that a 305/30 does not work on small tracks and/or cold weather. From my data - it looks like I can't get heat into the tire. The 275/35/19 all season had the same PSI and temp as the front at PMP.

Now it gets a bit complicated.
When set the dampers so it feels good dynamically on the springs, my potentiometers tell me I am bottoming out. I use all 40mm compression on the front and all 60mm compression in the rear. And this is not when hitting the curbs. This is on compression when hitting the hill at LRP or compression coming out of the last right hand downhill.

To compensate, I increased the low speed compression until I did not bottom out. For example at PMP fast corners are bumpy and my maximum compression was 30mm front or rear.

However, I read a convincing article that says "do not compensate for bottoming out with the dampers, increase spring". which got me thinking.

what if I increase the spring rate. After consulting with dogbone for sanity check I went for it. I had the rear 1100 from last year and I ordered 800 for the front.

On the way to Autocouture, I adjusted the rebound, mid speed and low speed compression to full soft and set the high speed to 10. Drove to the next thruway stop and adjusted HS to 12 on all corners. Now the car was hitting the joints on the road with a good "thump" and HS felt good.

Next stop increased rebound to +2 and car felt less bouncy. Next stop another +1 on the rebound and now car feels perfect. Mid Speed (MS) and Low Speed on full soft. The MS and LS will be used to fine tune the stiffer spring rather compensate for the spring, in theory anyway.

ACM installed the 1100 on the rear and I went for a ride. I felt very little difference. So this was good.

I am waiting for ACM to receive the 800 for the front and hopefully will test drive later this week.

The plan is to drive LRP on 4/16 with MS and LS on full soft and see if I still bottom out on the compression. If I don't I will add MS and LS as necessary. Before I add compression, if the car shift weight too quickly, will add rebound.

I am tempted to use the same all season tires I used at PMP for better comparison, but it would be hard decision to go slow in the name of science.

[Bartledoo]

Originally Posted by rhyary

New springs in the spring.

This a bit complicated to explain but I'll try.

Last year, before the season started, I installed a stiffer rear spring 1100 up from 1000. It is a divorced setup so you don't get a true up of 200.

I went testing it with a rear 305/30/19 tire. Keep in mind that testing in March and April means cold temp.

I had terrible time with oversteer. Finally, I gave up and went back to 1000.

Unbeknown to me, I had a broken compression shim on the front, and broken rebound shim in the rear.

Now, for this season I started with rebuilt JRZs, 750 front spring (been there for 4 years) and 1000 rear.

When I went to LRP with a 305/30/19 all season I had a terrible oversteer. So now my theory is that a 305/30 does not work on small tracks and/or cold weather. From my data - it looks like I can't get heat into the tire. The 275/35/19 all season had the same PSI and temp as the front at PMP.

Now it gets a bit complicated.
When set the dampers so it feels good dynamically on the springs, my potentiometers tell me I am bottoming out. I use all 40mm compression on the front and all 60mm compression in the rear. And this is not when hitting the curbs. This is on compression when hitting the hill at LRP or compression coming out of the last right hand downhill.

To compensate, I increased the low speed compression until I did not bottom out. For example at PMP fast corners are bumpy and my maximum compression was 30mm front or rear.

However, I read a convincing article that says "do not compensate for bottoming out with the dampers, increase spring". which got me thinking.

what if I increase the spring rate. After consulting with dogbone for sanity check I went for it. I had the rear 1100 from last year and I ordered 800 for the front.

On the way to Autocouture, I adjusted the rebound, mid speed and low speed compression to full soft and set the high speed to 10. Drove to the next thruway stop and adjusted HS to 12 on all corners. Now the car was hitting the joints on the road with a good "thump" and HS felt good.

Next stop increased rebound to +2 and car felt less bouncy. Next stop another +1 on the rebound and now car feels perfect. Mid Speed (MS) and Low Speed on full soft. The MS and LS will be used to fine tune the stiffer spring rather compensate for the spring, in theory anyway.

ACM installed the 1100 on the rear and I went for a ride. I felt very little difference. So this was good.

I am waiting for ACM to receive the 800 for the front and hopefully will test drive later this week.

The plan is to drive LRP on 4/16 with MS and LS on full soft and see if I still bottom out on the compression. If I don't I will add MS and LS as necessary. Before I add compression, if the car shift weight too quickly, will add rebound.

I am tempted to use the same all season tires I used at PMP for better comparison, but it would be hard decision to go slow in the name of science.

I’ll skip your theory about 305/30 rear tires not working on small or cold tracks, although it seems you need practice getting heat into tires…but adding rebound stiffness transfers weight faster rather than slowing it.

[rhyary]

Thanks for your input Bartledoo .
I would note that the same person drove the two size tires a week apart in similar temperature settings. While the two tires were different manufactures, they were the same category UHP All season.

I do like your theory that the driver need practice. It is why I continue to attend HPDE events.

[Bartledoo]

Originally Posted by rhyary

Thanks for your input Bartledoo .
I would note that the same person drove the two size tires a week apart in similar temperature settings. While the two tires were different manufactures, they were the same category UHP All season.

I do like your theory that the driver need practice. It is why I continue to attend HPDE events.

The temps are not the problem.

These are the temps and tires for my last five days on a one year old very smooth (smoothest in the northwest currently) track surface:
1/15: low 37 high 43, end of life high heat cycle hard slicks 305/645 (equivalent to 305/30 size) - damp in the first session, but totally fine with great balance and great pace all day
1/22: low 28 high 46, end of life high heat cycle A052 295/30 - totally fine with great balance and great pace. Rears overheated quickly of course because that’s A052
2/12: low 27 high 57, new conti force 295/30 - all good
4/1: low 32 high 50, extremely overcast and chilling breeze - current PB on the conti force in the morning sessions
4/2: low 39 high 54 - also good

[rhyary]

I had a great experience with rear 305/30/19 at Watkins Glen. Please note the driver was the same.

[DRLane]

Assume you're in Seattle? Just note the PWN maritime is very different from NE. Yes temp is absolute but the impact to the pavement is definitely different.

That said, agreed Rami, you should be able to bring tires to temp, especially all seasons. Given the tire temp has a max it'll reach and thus reflected in TPMS data log. What are you seeing? The rears don't heat up without the long straight / high speed straights for acceleration? Can't use aggressive accel/decel and a little constant speed weaving? Maybe embrace the oversteer to slide them?

[rhyary]

I have used all the common techniques allowed on trackday to heat up the tires. I am not allowed to swivel from side to side. So hard acceleration, and hard braking, acceleration and long braking works well for me.

The fact that I can bring to temperature other sized tires (and other kind of tires) should count for something.

I will report back on the springs when I get the car back.

[DRLane]

Originally Posted by rhyary

I have used all the common techniques allowed on trackday to heat up the tires. I am not allowed to swivel from side to side. So hard acceleration, and hard braking, acceleration and long braking works well for me.

The fact that I can bring to temperature other sized tires (and other kind of tires) should count for something.

I will report back on the springs when I get the car back.

The pace you're running means you have to be getting the requisite heat. Just curious what the rear data shows. I'm excited to incorporate the trailbrake tpms can enabled system you shared with me.

[rhyary]

Originally Posted by DRLane

The pace you're running means you have to be getting the requisite heat. Just curious what the rear data shows. I'm excited to incorporate the trailbrake tpms can enabled system you shared with me.

The TPMS showed no change in PSI or Temp on the rear 305/30/19. Not when I started on 29psi, and not when I dropped it to 24PSI.

[Bartledoo]

The problem is that you are driving and setting up based on fear of oversteer. You are not loading the rear like you load the front. Do not take this as an insult. I have always been afraid of losing the car due to oversteer as well (it’s actually the only driving related nightmare I have), and I can easily recognize it. My suggestion is to build a cheap sim rig and practice driving cars in iracing in your spare time. Intentionally get on the power too early. You will gain car control and confidence, and it will open up some possibilities for exploring the limit without feeling like you are going to die or look like a fool. It is frustrating and not necessarily enjoyable like driving in real life, but I’ve seen the results in myself and others. Vybz can vouch for how it can help.