HPDE experiments, results and observations

[Dbcgolf1]

Interesting thread - following.

What tire pressure are you running? Cold and hot pressures?

Thanks,
Dave

[rhyary]

Originally Posted by Dbcgolf1

Interesting thread - following.

What tire pressure are you running? Cold and hot pressures?

Thanks,
Dave

There is no straight answer.
Rather than explaining all my iterations, let me share what I will be doing on my next track day.

I drive to the track, my next day is at NYST. So that would be about 70 minutes drive. when I arrive my tires are not "cold". They are above ambient temperature.

I find that to be a good time to set (project) what I want my hot PSI to be.

So I am setting the rear to 26 and the front to 30. Then when I come off the track I tried to check pressure as soon as I can, my goal is to not exceed 38 on the front, and Between 32 and 35 on the rear. More likely 32 hot.

I am sure others will have plenty to say about my choices. But since I pay the bills for buying tires, I do see the relationship between lowering tire pressure, laptime and tire longevity.

The rear can take a wide variety of temperatures. But for me personally I don't like the feeling of loose rear at slower corners. Because I am on 1100 rear spring, I learned that the softer I go in the rear, the more confident I am. So I am setting that as a priority.

The obvious advise would be to go softer in the rear. But that creates a problem on the high speed. I already came from 900 than 1000 rears.

As every one who goes to trackdays know, it is an ever changing variables which make chasing a balanced car a challenge. There is not one best setup.

In short - I setup at "cold" which is actually warm - rear on 25-26 and front 28-30.

[rhyary]

Originally Posted by DRLane

I know you run back to back laps, but sometimes it's best to befriend someone that's running in the opposite sessions. And do it for each other.

The Longcare Pyrometer is nice but you need to operate it carefully. The tablet is connected to the probe with Bluetooth and Using the probe requires being careful on the tip.

So until I use it enough and learn how to handle the tablet, probe and tip, and how it records the temps I am not going to share it.

[rhyary]

Originally Posted by b4hand

Randy Pobst always says braking warms up tires more than anything else.

I agree with Randy :-)
I typically accelerate and brake on my first lap multiple times to warm up the tires. I don't swerve back and forth mostly because HPDE organizers asks us not to do so.

[rhyary]

Originally Posted by Bartledoo

On a soft tire with low pressure the shoulder can get f'd pretty quick.

On one of my iterations I went out on 20-22 PSI and that was not great idea with 3600Lbs car.

[Datka]

Originally Posted by rhyary

I agree with Randy :-)
I don't swerve back and forth mostly because HPDE organizers asks us not to do so.

I can see why HPDE organizers don't allow that. I have seen F1 and Indy car drivers crushing their cars during tire warm ups.

[admranger]

In the BMW Club Racing School, my instructor, a former pro racer (Carl McGinn) emphasized braking as the way to warm up tires.

[dparm]

Originally Posted by admranger

In the BMW Club Racing School, my instructor, a former pro racer (Carl McGinn) emphasized braking as the way to warm up tires.

Yes, on my out laps I will do some weaving but also a lot of hard acceleration and hard braking. This also ensures I get the pad into it's MOT range and I don't have an embarrassing off on lap 1.

[rhyary]

Heading over to NYST with nicksm3. clear sunny skies at 26f degrees.

This is crazy. Second trackday on sub freezing temps on summer tires.

Today I am on Pirelli tires
Front 285/30/19 Asymmetrico 2 second day for them
Rear 305/30/19 Troffeo I got from eBay - first day.

Unlike last time at PMP, I am going on the rear with the minimum PSI cold - 25psi and let it go up to whatever. I hope to get it up to 30-32.

Front will be on 28 cold and will not let it go above 38 hot.

For the soft air pressure I am back to rebound at half the seetings (12)

LS is now at 2 (slowest is 1)
HS is on -4 from sloest (19-4)

I am sparing you from the details as to why I am trying these settings. But there are lots of driving the car on my test loop behind these setting. While public roads do not let me test the car at speeds, I do go through bumpy ramps at 70-80 mph and I can tell how the car takes the bumps. (skip or activate the traction control)

The way I test the "stickiness" is by driving with full traction control on (no even mdm) and monitor the traction light. If it comes on, the car is skipping or losing traction.

An interesting factoid is that I have this 70-80mph turn that has a "whoopty do" in the middle of the turn. And it is only recently when I increased the LS (slower) that the traction control is no longer activated. Which is a puzzle I was trying to solve for a long time.

This is a similar "road characteristics" I have in the middle of NYST straight. I was always annoyed that when on MDM the traction control would go off in the middle of the straight.

While I don't here this a lit here, but you can imagine that if I can correlate suspension tuning on a loop around my house to trackday setup, it saves a huge amount of time coming to trackday. My goal is to just drive.

Lastly, the suspension engineer I am working with is encouraging me to just play with tire pressure at the track. And I would agree once I get to a JRZ setup I like and trust.

Will share with you today results when done, but not sure what to expect from a day that have the day is 40f and the second half is at 50f.

Since it is a sunny day, the track should be up to 70-80f given what I saw at PMP.

[nicksm3]

Interesting turn of events ...meaning the weather lol!
But you drove great today, really learning the car and the capabilities of being at the limit.
Great seeing you today

[rhyary]

Using ALL the track

[rhyary]

@nicksm3 friend Dimmy (sp) came with me for few laps and suggested to take the rear to a much softer settings.

We did, and the car felt a lot better. In addition to taking as much air from the rear tires.

Still some oversteer here and there and that can also be the Trofeos only coming up to 120f on a cold day.

[tsk94]

Nice save!

[Datka]

Originally Posted by rhyary

Using ALL the track

Looks like you put your right tires on the grass. Try not to do that at Watkins Glen.
Also, I suggest to hold your hands at 3 and 9 oclock on the steering wheel at all times. That way you can control it much better and your hands movement in the right direction will be much quicker.
I am pretty sure you would not have saved that spin at a higher speed based on the way you shuffled your hands.

[rhyary]

Today, Saturday, I spent the morning chasing the suspension settings.

First, I confirmed that the Low Speed (LS) on the JRZ canister is counter to what I was told.
1 is soft and 10 is stiff.

This became a bigger issue this year because I went to 1100 rear spring. While great at high speeds, I have been fighting oversteering coming into a slow corner such as:
Turn 3 LRP
Turn 3 NYST
Turn 3-4-5 PMP.

Since the LS is where you tune your US/OS it is more critical to get it right.

My suspension engineer diagnosed the issue as a diagonal relationship. The relationship between the Front Right and the Rear Left can be expressed in a mathematical equation.

So he wrote a math channel to express my pots LF/RR and RF/RL and we indeed can see the issue.

We compare two sessions from yesterday NYST. both laps were 1:39 pace. one was at 12pm before I made the rear full soft, and 4pm session after I made the change to full soft.

The ration indeed shows the front and the rear are lagging each other. This can be corrected with the LS.

After bunch of test drives I am setting up the car as a baseline as follow:

Front:
Rebound 10, HS 4, MS 4, LS 5 (mid point)
Rear
Rebound 8, HS 6, MS 4, LS 5 (mid point)

JRZ defines the Medium Speed (MS) as a setting for when the car is fully loaded on the sway bar mid corner. This would be Turn 8-9-10 sequence at NYST where you load the sway bars at 100-80-70 mph slalom.

While I do have slight oversteer going thru 9, I am not going to address it at the moment since it is not yet a priority.

Tomorrow is Palmer, unfortunately rain is in the forecast. But I hope to collect more data on the setup.

Then coming back to NYST on 5/1 and I have high hope that not only my setup be sorted up, but I can now make changes based on conditions.

It is a marathon, not a sprint.

Enjoy two laps on 1:39 chasing nicksm3. His fabulous car at full display

[rhyary]

So PMP in the rain, 45 ambient, 65 track temp, tires cold and not coming up to temp.

Did 50 laps over 6 session.

Last session it finally stopped raining.

Rear 275/35/19 Ecsta 720 first day
Front 275/30/19 FFI500.l second day

This was the combination I did best time last year at PMP.

Constantly managed oversteer and oversteer.

Lap in the rain

Lap in the wet (no rain) and car felt good

[rhyary]

This up and coming NYST 5/1/21 trackday will be very interesting one.

Provided that I will get the Brembo brackets tomorrow as UPS says, my brakes issue should be sorted out and I can focus on more productive efforts.

The revelation that my LS full soft is 1, changes my setup dramatically. You can imagine what happens to your car when you think you are making the rear softer, while in fact you are making it stiffer. Yep, unexplained oversteer and lots of frustration, and lots of learning to control oversteer. Perhaps not a bad situation because I am all about managing traction. But the situation got old and I was getting frustrated.

So, the good news is that when I had one session at PMP on wet cold but not raining, the car felt terrific and most importantly I immediately gained confidence. It is hard to imagine how different it felt from the session before that.

I would like to think that if I can feel the difference between raining track and wet track then I must have a working butt-o-meter that is functioning.

So, the good news is that the weather forecast is very similar to the weather from a 4/23/21. I have the same 2013 305/30/19 Trofeo on the rear. While it is a second day on them, they are good enough for what I am looking.

The front will be a good first experiment. I really really liked last year the 295/30/19 MPSS on the rear and I wanted to try the 285/30/19 MPSS on the front. I am expecting a different experience than the MPS4S. I tore the MPS4S apart on the front and I expect the MPSS to be more track oriented tire.

The temp will still be cold, 45 degree is cold. However, on a sunny day at least I anticipate the track surface to be at over 90f.

I honestly just want the rear to have lateral traction coming in to a slow turn on trail braking. Once I have that, I can go back to the usual program.

Tire pressure cold (end of a break from last session just before going on the track again) is 25 rear and 28 front.

While I keep trying different tire pressure to see what happens, I am coming back to these cold temps as an excellent base line. The advantage of this "cold" psi is that it is not dependent on coming off the track and getting reliable reading. Taking hot PSI is important but hard to do right given that the last lap may not be hot enough, or the trip to the paddock is too long. Especially on cold track. Driving slow on cold track sucks the temps out of the tires very quickly.

[Bartledoo]

How long have you been adjusting your dampers backwards?

[rhyary]

Originally Posted by Bartledoo

How long have you been adjusting your dampers backwards?

The LS - Since I got them.

But I was not adjusting the LS that much. kept it on 6 for a along time.

My thoughts are that it was not very important when I was on 900 and 1000 rear spring because these springs were too soft for the way I was driving the car. However, for 2021 I am on rear 1100 and that requires a softer low speed and more critical to get it correct. So as I was making is "softer" moving toward 10, it got worse and it made no sense.

It makes no sense that LS 10 is the soft settings and I asked JRZ multiple times the first year I got the system about it. And the second year as well and I always understood the 10 was soft.

It is water under the bridge at this point but as far as documentations are concerned, I couldn't find, and still can'd find a reference to LS settings. All I can find is "make the LS soft or stiff" but not "start at 1" or "start at 10"

Grrrrrr…

Unlike the HS. the HS is clearly documented.

[dparm]

Surprising to hear ambiguity from a company like JRZ. Do you have a local shop/reseller supporting you with that purchase who knows the nuances?

[rhyary]

Originally Posted by dparm

Surprising to hear ambiguity from a company like JRZ. Do you have a local shop/reseller supporting you with that purchase who knows the nuances?

My virtual coach says it(how equipment works) happens all the time in the racing world.

I am working with a suspension engineer that, using Aim data profiles, we now verify everything I am being told, no matter who is saying it.

We did verify that 19" wheels are a good choice (sorry, couldn't resist)

[tsk94]

Originally Posted by rhyary

We did verify that 19" wheels are a good choice (sorry, couldn't resist)

Well, we now know your suspension 'engineer' doesn't know what he's talking about.

Sorry.. couldn't resist