P3D+ Second Track Day - thoughts

[Nocturnal]

The car is a blast to drive on the track overall. I'm finding that the traction control really makes it hard to lose control even when driving at the edge. In my class there aren't any cars that can beat me on the straights and not so many that do better on the curves (with my stock tires and bad driver mod at least).

Heat is the main issue. A ton of power is held back once the car get's too hot. Lap 1-2 are always great, 3 is a little tight, but 4 and 5 wind up seeing what I feel is a 25% power reduction. Cars that I easily passed in early laps would be able to pass me. For a comparison, on the longest straight at Heartland Motorsports in Topeka I was hitting about 107 on most fresh-ish laps. On the laps where the car was overheating that speed dropped to the low 90s.

I'm optimistic about track mode helping but I'd be surprised if software only could resolve this problem. I think we will need some sort of aftermarket cooling solution to be really competitive. Anybody want to help design a system that sprays CO2 onto the coolant radiators when they get past a certain temp?

Bonus round. At the end of the day I plugged in to get some extra juice for the drive home and my charger decided to not work. I've been seeing intermittent "charging reduced" errors but haven't taken it in yet. At the SC now and they are replacing the onboard charger. I also routed on back roads on the way home and hit a patch with giant potholes. Turns out I have two bent rims. $1400 down the drain.

 

[MountainPass]

Oh no! Sorry about your wheels

Hopefully track mode lets the P3D+ spend some more quality time out on the track.

 

[Xenoilphobe]

The car is a blast to drive on the track overall. I'm finding that the traction control really makes it hard to lose control even when driving at the edge. In my class there aren't any cars that can beat me on the straights and not so many that do better on the curves (with my stock tires and bad driver mod at least).

Heat is the main issue. A ton of power is held back once the car get's too hot. Lap 1-2 are always great, 3 is a little tight, but 4 and 5 wind up seeing what I feel is a 25% power reduction. Cars that I easily passed in early laps would be able to pass me. For a comparison, on the longest straight at Heartland Motorsports in Topeka I was hitting about 107 on most fresh-ish laps. On the laps where the car was overheating that speed dropped to the low 90s.

I'm optimistic about track mode helping but I'd be surprised if software only could resolve this problem. I think we will need some sort of aftermarket cooling solution to be really competitive. Anybody want to help design a system that sprays CO2 onto the coolant radiators when they get past a certain temp?

Bonus round. At the end of the day I plugged in to get some extra juice for the drive home and my charger decided to not work. I've been seeing intermittent "charging reduced" errors but haven't taken it in yet. At the SC now and they are replacing the onboard charger. I also routed on back roads on the way home and hit a patch with giant potholes. Turns out I have two bent rims. $1400 down the drain.

Get rid of those boat anchor stock wheels and replace it with lighter, stronger, forged wheels...see group buy below..
Titan 7 T-S5 (Set of Four Wheels) - 19x9.0 / +35 / 5x114 for Tesla Model 3 (Deposit) | Evasive Motorsports

Weight Savings:

Titan 7 T-S5 Wheel
19x9.0 / +35 Wheel Weight: 20lbs

Stock Wheels
18x8.5 +40 Weight: 21.6 lbs (Without Aero Cover), 23 lbs (With Aero Cover)
19x8.5 +40 Weight: 25.0 lbs
20x8.5 +35 Weight: 30-32 lbs (Speculated)

 

[kbecks13]

Get rid of those boat anchor stock wheels and replace it with lighter, stronger, forged wheels...see group buy below..

Yea but none of those wheels are really a great size for track use :/

If Evasive can offer some 19x9.5s, i'm interested - and i know, you will ask me to email them

 

[Xenoilphobe]

I think @MPP got 19 X 10 +35's to fit with 275 rubber all around... waiting to see his track test...
I like your idea with the squirt bottle mister on the radiator...

 

[kbecks13]

I think @MPP got 19 X 9.5 +35's to fit with 275 rubber all around... waiting to see his track test...

They actually used 19x10 +35, but that's on a RWD car which is a little different from P3D. Either way, 9" width is a little too small for me since i want a track set.

I'm optimistic about track mode helping but I'd be surprised if software only could resolve this problem. I think we will need some sort of aftermarket cooling solution to be really competitive. Anybody want to help design a system that sprays CO2 onto the coolant radiators when they get past a certain temp?

Here's a video going over the Model 3 cooling system. I really want to slap some thermocouples on the various chiller lines/components and get some temperatures during track runs. @MountainPass you guys should try this if you can

Once we know what the limiting factor is (i.e does the coolant get over 100F or something) we can better discuss potential mods to reduce heat soak.

 

[Xenoilphobe]

@kbecks13 You are right it was 19 X 10 +35, just updated the post above.. had to go back and find the thread... it was here Buying Performance Tires - Best size for 18-inch wheel?

 

[Osubeaver]

Are you attending HPDE or an actual time attack event? Just an observation about the perspective of using language about being beaten or competitive in your class.

My approach to driving HPDEs was to have fun, but more importantly to work on my own driving technique. Certain cars can really mask bad driving habits and if your focus is on "winning" you tend to focus less on things you can do to improve. I started with a Mini Cooper S and my biggest frustration would be driving behind a Mustang holding me back on the turns and then full gas on the straight with no point by and I didn't have the power to overtake.

Not saying that is what you are doing, but I think if you approach the event more about how you can improve your own driving style you may find yourself worrying less about the cars around you. Giving a point by shouldn't be something to feel ashamed about, but contributing to others having the best experience as well.

Sorry for the preamble, but it is because at least with my forced induction cars that would suffer some type of heat soak my approach would be to lift on the straights or short shift to try and reduce heat build up. I'm not sure if this will work with an EV, but you may want to try lifting on the straights and going hard in the turns. It is hard to do if you're not willing to give a point by or feel bad about getting passed. At least in my experience at an HPDE we're a fraternity of car guys/girls just trying to have fun.

 

[omgwtfbyobbq]

FWIW, I'd try to slap a clamp-on ammeter on the induction motor before anything else. I recall Elon saying that was the limitation for the S in the past, and if it's also the limitation for the P3D, it should be pretty obvious when comparing the current the induction motor draws before and after power is limited.

 

[brianman]

My approach to driving HPDEs was to have fun, but more importantly to work on my own driving technique. Certain cars can really mask bad driving habits and if your focus is on "winning" you tend to focus less on things you can do to improve.

Giving a point by shouldn't be something to feel ashamed about, but contributing to others having the best experience as well.

At least in my experience at an HPDE we're a fraternity of car guys/girls just trying to have fun.

Great feedback. I hope to see you at some track events. Your perspective aligns with mine pretty well, based on this post.

 

[Nocturnal]

Like last time I had a ton of questions and interest on the car. These events are a blast and I recommend anyone that likes cars in general to attend one. You can push yourself or just chill and have fun (or both).

I think @MPP got 19 X 10 +35's to fit with 275 rubber all around... waiting to see his track test...
I like your idea with the squirt bottle mister on the radiator...

Should be easy. CO2 bottle, some off the shelf nozzles and a switch.

Are you attending HPDE or an actual time attack event? Just an observation about the perspective of using language about being beaten or competitive in your class.

My approach to driving HPDEs was to have fun, but more importantly to work on my own driving technique. Certain cars can really mask bad driving habits and if your focus is on "winning" you tend to focus less on things you can do to improve. I started with a Mini Cooper S and my biggest frustration would be driving behind a Mustang holding me back on the turns and then full gas on the straight with no point by and I didn't have the power to overtake.

Not saying that is what you are doing, but I think if you approach the event more about how you can improve your own driving style you may find yourself worrying less about the cars around you. Giving a point by shouldn't be something to feel ashamed about, but contributing to others having the best experience as well.

Sorry for the preamble, but it is because at least with my forced induction cars that would suffer some type of heat soak my approach would be to lift on the straights or short shift to try and reduce heat build up. I'm not sure if this will work with an EV, but you may want to try lifting on the straights and going hard in the turns. It is hard to do if you're not willing to give a point by or feel bad about getting passed. At least in my experience at an HPDE we're a fraternity of car guys/girls just trying to have fun.

HPDE. I didn't see it a competition, just trying to compare the cars relative performances.

Don't worry, I gave plenty of point bys, sometimes because a car was faster/driving better, sometimes because I just wanted a break. Regarding heat, once it was hot even a very relaxed lap was not enough to get it cooled down.

 

[Gavyne]

Damn the car looks good out there, represent!

With Track Mode, they pre-cool the batteries so it should help make it last longer.

 

[Nocturnal]

Damn the car looks good out there, represent!

With Track Mode, they pre-cool the batteries so it should help make it last longer.

That and I hope if proactively keeps them cooler at the expensive of battery life as soon as it turns on. I was plugging in between runs so a little extra wasted juice won't matter.

 

[Osubeaver]

Wow the 3 really does look great on track! I see you attended a Track Night Event. I really love what the SCCA is trying to do with those events in making track days really accessible, but if you can find a local event that includes driver training and an instructor I think you'll find it really beneficial.

 

[kbecks13]

FWIW, I'd try to slap a clamp-on ammeter on the induction motor before anything else. I recall Elon saying that was the limitation for the S in the past, and if it's also the limitation for the P3D, it should be pretty obvious when comparing the current the induction motor draws before and after power is limited.

I don't think you can get to the individual conductors to clamp them and also wouldn't this just tell you what the dots on your screen already say (that power is being limited)? It would be interesting to understand what temperature the coolant and AC refrigerant are at when power starts being limited.

If the AC refrigerant stays a similar temp while battery/motor coolant increases in temp, it shows that the plate heat exchanger isn't soaking up enough heat. If both items increase in temp, it shows that the AC compressor isn't capable of enough cooling. This then points you in the right direction in terms of weak links in the system.

 

[omgwtfbyobbq]

I don't think you can get to the individual conductors to clamp them and also wouldn't this just tell you what the dots on your screen already say (that power is being limited)? It would be interesting to understand what temperature the coolant and AC refrigerant are at when power starts being limited.

If the AC refrigerant stays a similar temp while battery/motor coolant increases in temp, it shows that the plate heat exchanger isn't soaking up enough heat. If both items increase in temp, it shows that the AC compressor isn't capable of enough cooling. This then points you in the right direction in terms of weak links in the system.

I think you can, assuming the conductors for the front motor are similar to the ones for the rear motor.

https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=40001&flag=1

If the car starts limiting power and the induction motor current goes from 100+kW to something a lot lower, my guess is the induction motor is the limitation. You can always measure rear motor output in the same way and see if that's limited significantly when power is limited.

 

[kbecks13]

If the car starts limiting power and the induction motor current goes from 100+kW to something a lot lower, my guess is the induction motor is the limitation. You can always measure rear motor output in the same way and see if that's limited significantly when power is limited.

But Tesla could be commanding a lower max power output based on the temperature of the motors/battery/other power systems. So just because you see reduced power at a motor doesn't mean that something is actually wrong with it, Tesla could just be limiting output via software to protect reliability.

My guess is that they reduce power output based on the temperature of various components, so i think we need to understand what those temperatures ARE when they start to reduce power.

 

[omgwtfbyobbq]

But Tesla could be commanding a lower max power output based on the temperature of the motors/battery/other power systems. So just because you see reduced power at a motor doesn't mean that something is actually wrong with it, Tesla could just be limiting output via software to protect reliability.

My guess is that they reduce power output based on the temperature of various components, so i think we need to understand what those temperatures ARE when they start to reduce power.

I agree if both motors have significant power reductions. If the induction motor's output drops a lot more, then I'd look harder at it, mostly because that's what Elon referenced as the thermal limitation in the past.

 

[P3D+]

Congrats does look like fun. Track mode OTA before the year is out...... fingers crossed!

 

[MountainPass]

They actually used 19x10 +35, but that's on a RWD car which is a little different from P3D. Either way, 9" width is a little too small for me since i want a track set.



Here's a video going over the Model 3 cooling system. I really want to slap some thermocouples on the various chiller lines/components and get some temperatures during track runs. @MountainPass you guys should try this if you can

Once we know what the limiting factor is (i.e does the coolant get over 100F or something) we can better discuss potential mods to reduce heat soak.

We have been monitoring temps and working on this problem. It's not a straight-forward problem to solve as the ideal solution requires integration with the vehicle's electronics - unless you add a supplemental refrigeration system!

Our goal is to do some testing to see if there are any viable products that make a meaningful improvement. No doubt we can change parts - but we're not going to pursue anything unless we can prove it will gain at least 1 extra lap before overheating.