Define: Track worthy?

[brianman]

It's commonly asserted that the Model S isn't a track car. Tesla's own positioning seems to be in line with that. That doesn't stop some of us from burning some tires, etc. at, um, "special purpose high speed locations with driver education events".

With the Model 3, there are some discussions about whether the vehicle (in at least some configurations) should be considered "track worthy". More strongly, I think everyone is hoping that Tesla is seriously aiming to making the 2020+ Roadster clearly "track worthy" (and perhaps "track dominant").

I'd like this thread to focus on the defining attributes of "track worthy", with a preference toward criteria that can be tested and vetted by "mere mortals" (I don't live near the 'Ring) often and with comparable results.

Anybody want to start the ball rolling?

 

[Derek Kessler]

Model 3 suffers from the same problem as the Model S and X: keeping the battery cool means limiting power draw once it gets too hot. And that happens relatively quickly.

 

[AWDtsla]

Model 3 suffers from the same problem as the Model S and X: keeping the battery cool means limiting power draw once it gets too hot. And that happens relatively quickly.

Given neither Model S or X have a problem cooling their battery, we're free and clear here.

 

[Uncle Paul]

Some other manufacturers void your warranty if your car is GPS located on a racing surface (track). Others void after so many full throttle starts or with multiple launch control starts.

Every manufacturer has it's own policy. ''

Dodge used to encourage their Viper owners to "take it to the track" they sometimes even would sponsor/support customer track events.

Tesla has not produced full on track cars, but have modified some of their street models to provide additional performance capabilities both on the street and track.

I would expect to see owners taking their street legal cars to certain track events. They will run them as hard as they can and reveal their limitations.

Full on competitive track cars cost millions.

 

[Petra]

From a criteria standpoint with regard to Tesla's cars specifically, being able to make it through a session without a meaningful reduction in power due to thermal limitations is about the only one I can think of... nearly everything else can be fixed.

On a related note, @MountainPass seems to be having fun: Vendor - MPP Model 3 Build Thread

 

[PessimiStick]

Model 3 suffers from the same problem as the Model S and X: keeping the battery cool means limiting power draw once it gets too hot. And that happens relatively quickly.

Not only is that not true for the 3, it's not even true for S/X. It's never been the batteries that are a problem.

 

[thelastdeadmouse]

I'm hopeful that the more efficient motor design for Model 3's will mean significantly reduced or eliminated thermal bottlenecking. It doesn't seem like a big improvement at first glance, but if you swap a 98% efficient motor for a 99% efficient motor, you've improved performance by about 1% but you've halved the cooling required.

To me for a Model 3, track worthy means performance on par with other sports sedans in its price range, with no or negligible thermal bottlenecking during a 10-20 minute session, not including warm up and cooldown laps.

 

[AWDtsla]

I'm hopeful that the more efficient motor design for Model 3's will mean significantly reduced or eliminated thermal bottlenecking. It doesn't seem like a big improvement at first glance, but if you swap a 98% efficient motor for a 99% efficient motor, you've improved performance by about 1% but you've halved the cooling required.

It's going to be more like 60% vs 94%. There isn't one efficiency number but a 3 dimensional efficiency map.

 

[animorph]

I'm with Petra, make it through a (20 minute?) track session with at most minor degradations in braking and acceleration. Upgraded brake pads/brake fluid or other standard race prep is fine.

 

[MountainPass]

The Model 3 with some upgrades is most certainly "track worthy" - I define this as being able to run for 15 minutes straight without significant performance degradation for a novice to moderate skill driver.

Most professional drivers will be able to overload even a performance street car on the track - even a BMW M3, Porsche 911 or Audi S4 can be pushed over the edge in only a few laps on factory brake fluid and brake pads. I have faded Ferrari 458 brakes in 3 laps before, simply because unless you have carbon ceramic brakes, street brake pads will always be different than track brake pads.

However, these cars would still be very much considered "track worthy." It is accepted that if you really want to race these cars you need to change pads at the minimum.

The Model 3 loses about 10A and 3V per lap between power limitation and SOC going down, which works out to about 5kW of power (6.7hp). This comparison was made at the exact same Motor RPM.

In very hot conditions after longer running the Drive unit does significantly reduce power, we had the drive unit pull back 150A after about 10 minutes of on-track abuse. It's our goal to find out what we can do to improve that

 

[brianman]

Model 3 suffers from the same problem as the Model S and X: keeping the battery cool means limiting power draw once it gets too hot. And that happens relatively quickly.

Link to examples of when/where this has occurred for Model 3?

 

[brianman]

session

We should define (for the purposes of this thread) what the "session" requirements are for measuring.

As an example, some lapping events that I attend have sessions ranging from 15min to 30min.

 

[AWDtsla]

In very hot conditions after longer running the Drive unit does significantly reduce power, we had the drive unit pull back 150A after about 10 minutes of on-track abuse. It's our goal to find out what we can do to improve that

How many amps are available from the pack?

 

[brianman]

Not only is that not true for the 3, it's not even true for S/X. It's never been the batteries that are a problem.

I'm fairly confident the battery is a problem on my 2012 S P85. It was still a problem, though less so, on my P85D. It was even less so on my P85D. On my P100D S, I'm not sure if the battery is part of the problem or not.

How do you know it's not the problem for at least some S/X?

 

[brianman]

It's going to be more like 60% vs 94%. There isn't one efficiency number but a 3 dimensional efficiency map.

Might be worthy of it's own thread, but I'd like to here more about how you arrived at 60% and 94% values.

 

[brianman]

The Model 3 loses about 10A and 3V per lap between power limitation and SOC going down, which works out to about 5kW of power (6.7hp). This comparison was made at the exact same Motor RPM.

Can you elaborate on this? Is this being shown in the in-car UI in some way, or only available via (external) measurement?

Also, can you edit your post (if possible) or indicate in a subsequent post the configuration (LR, but RWD/AWD? P? Px2?) and firmware version. Thanks.

 

[TexasTeslaRacing]

Model 3 suffers from the same problem as the Model S and X: keeping the battery cool means limiting power draw once it gets too hot. And that happens relatively quickly.

This is incorrect. I have taken the Model 3 to the track and it performed very well. Never had the power reduced and never went into "limp" mode. My previous Model S was only capable of 2-3 laps before a reduced power setting kicked in. Hope this information helps. You can track this car all day!

 

[AWDtsla]

Might be worthy of it's own thread, but I'd like to here more about how you arrived at 60% and 94% values.

Just an guess on AC induction vs PMAC, combined with that I see 5.75RM consumed per quarter mile run, including as much regen as possible. A lot of that is wasted in aero drag, but that's still something like 4% total system efficiency. Regardless, as torque and RPM rises, AC induction efficiency falls off rapidly. I have no idea how far Tesla pushes it, but I assume that it's very hard and therefore exists a good tradeoff to capping motor power all the time in exchange for much longer to motor/inverter overheat conditions. Someone that wants to race the car would actually have to get the efficiency maps and tune the computer to operate at the best points. Win the race, not just the first lap.

 

[TexasTeslaRacing]

I'm fairly confident the battery is a problem on my 2012 S P85. It was still a problem, though less so, on my P85D. It was even less so on my P85D. On my P100D S, I'm not sure if the battery is part of the problem or not.

How do you know it's not the problem for at least some S/X?

It will be a problem for any Model S or X on any track. The Model 3 has a different motor and power inverter, hence you can go all out for 20-30 minutes.

 

[TexasTeslaRacing]

Just an guess on AC induction vs PMAC, combined with that I see 5.75RM consumed per quarter mile run, including as much regen as possible. A lot of that is wasted in aero drag, but that still something like 4% total system efficiency. Regardless, as torque and RPM rises, AC induction efficiency falls off rapidly. I have no idea how far Tesla pushes it, but I assume that it's very hard and therefore exists a good tradeoff to capping motor power all the time in exchange for much longer to motor/inverter overheat conditions. Someone that wants to race the car would actually have to get the efficiency maps and tune the computer to operate at the best points. Win the race, not just the first lap.

Here's a Teslfi power usage from a track day last weekend. 2.5 mile technical course. You can see I drive almost 20 miles and used 83.54 rated miles. 932wh/mi or 24% efficiency.