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Model S on the Track - A Review

Discussion in 'Model S: Driving Dynamics' started by Doug_G, Jun 4, 2013.

  1. Doug_G

    Doug_G Lead Moderator

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    #1 Doug_G, Jun 4, 2013
    Last edited: Jun 4, 2013
    On Monday I had the opportunity to try the Model S P85 on the track at Shannonville Motorsports Park.

    This is a very old facility. It doesn't have any elevation changes, but it has a very technical and challenging track. It's also one of the more forgiving tracks if you make a mistake, because usually you just trim the grass. Most importantly, and perhaps uniquely among Canadian tracks, it has charging stations!

    First, here are a couple of pics, I posted more in the Canada section at Shannonville Motorsports Park - June 3 - Page 3

    m.jpg

    n.jpg

    I'm not really interested in tracking my Model S on a regular basis. For that purpose I normally beat up on an 11 year old Honda S2000. I did want to give the Model S a try on the track, and I particularly wanted to understand its limits better. That can come in handy in emergency situations. (This really paid off last year while driving my previous car, an Infiniti G37. I just barely managed to avoid what would have been a very serious collision.)

    Good Points

    The Model S, when full power is available, really pulls.

    The lack of a loud engine means you can really hear what the tires are doing. Lots of feedback.

    Despite the fact that I have an "ordinary" Performance, not a P85+, the car was very poised on the track. I'm pretty happy with the handling.

    Unlike the Roadster you can turn the Regen Braking down. While I love using Regen during daily driving, it interferes significantly with proper racetrack cornering. With the Roadster it is something of a nuisance, and you really have to adapt your driving style to it. In the Model S you can set Regen to Low and it's a non-issue.

    The car is remarkably well balanced, especially considering that it is a street car. Although it is big and heavy, in many ways the handling is superior to the Roadster. The Roadster is very prone to understeer. You have to get the adjustable suspension, adjust it, and put on sticky tires... then it turns in okay. And my old G37 just pushed and pushed.

    Not so the Model S. It doesn't have a problem with pushing on corner entry. I'm really quite pleasantly surprised at how good this is. It likes a little trail braking to help rotate the car, but I'm good with that!

    It isn't too prone to oversteer either. I'm used to an S2000 AP1, and if you don't keep the throttle on after the apex you'll probably spin it. The P85 isn't like that at all, but you can break the tail loose, and I'm not talking about power oversteer. I had the tail pop out once while rounding the tight double-apex at Shannonville. But it wasn't a big deal, a small countersteer stabilized the car immediately. Nice!

    With a CS-90 (70A 240V delivered) charge station on site, I had enough juice to keep going all day. The charge level slowly dropped through the day, but it was always enough to keep going. (I skipped the last session just so I could get a head start on charging for the drive home.)

    Bad Points

    The big problem with the Roadster is the air cooling system. After a few hot laps at Shannonville the motor is getting too hot and the car backs down the power. After a few more the car is getting pretty slow. I was hopeful that the Model S, with its all liquid cooled drive train, wouldn't get as hot as quickly.

    Unfortunately this did not prove to the be the case. Driving on the track takes almost 4X as much power as driving on the street. I was seeing 750 Wh/km (1,200 Wh/mi), sometimes more. There are no temperature readouts on the Model S (annoyingly), but it certainly does show you when it backs down the power.

    That power limit came on the second lap(!). It would pull power back to about 160 kW, which was still quite usable. That would last about ten minutes before I started turning into a "rolling chicane". If I did a slow lap it would get faster again, for a while. A better approach was to pull into the pits. After a minute the power limit would disappear from the speedometer screen. I'd wait several more minutes then head out for another few laps.

    (Some on these forums have speculated that the car was deciding to limit power based on Projected Range. I have to disagree - it's pretty clear that the limiting factor is drive train temperature. Without readouts I can't tell if it was the motor or power electronics... but you can tell by how fast it happens that it's one of the two. Based on my Roadster experience the battery pack has way too much thermal inertia for it to be the cause.)

    Interestingly, the brakes and tires never really got that hot. It probably helps that the car has huge rotors, but the relatively quick power limits were probably just as much a factor. On my first lap I could easily get to 177 kph on the back straight without going late on the braking. After ten minutes I was only getting maybe 145 with really late braking - and I was only braking that late because otherwise I'd be coasting to the corner (I was taking the apex at about 95).

    A Tip

    The Model S doesn't really have ideal seats for pulling G's. Without proper support I would have had to hold myself in place with the steering wheel, which is bad for steering control and rather bad for my back and arms. I would have been very stiff the next day.

    Luckily I figured out an easy way to greatly improve things. I created a driver profile called "Track", with a suitable position for track driving. I then created another profile called "Load", which pulled the seat all the way back. I got in, pressed Load, belted up, and tugged a few times on the shoulder belt until it locked. Then I leaned forward to maintain the pressure on the belt, and reached for the driver profiles and hit Track. The seat moved forward and the belt snugged up real tight. Any tighter and my eyes would have been bulging. Pretty darn good - I was really locked in place.

    I found the next day that my legs were a bit stiff, so evidently I was still bracing my legs against the door and console, but my back, arms, and neck were just fine.

    Conclusion

    Despite its large size and weight, the Model S has amazingly good handling. One of the more experienced (and fast!) drivers in our club passed me in his highly modified turbo Miata, but he said it did take a bit of time to catch up to me.

    Unfortunately the cooling system can't keep up with track use. After 10 minutes it was the slowest car on the track. With a better cooling system the Model S could really hold its own.

    I did get a lot of comments from other drivers about how good it looks! :biggrin:
     
  2. 7racer

    7racer Member

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    great great great post! love the feedback from another track junkie.

    However, I'm kinda bummed the cooling system couldn't keep up. I wonder what can be done to make a future performance Tesla survive on the track?
     
  3. Doug_G

    Doug_G Lead Moderator

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    I'm sure it would be no biggie for Tesla's engineers to design a more powerful cooling system. They probably don't do it on Model S for cost considerations (and maybe also cosmetic design considerations - it has rather small radiators).

    Hopefully Roadster 3.0 will have an upgraded cooling system that will allow protracted heavy power usage.
     
  4. KOL2000

    KOL2000 Member

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    What an awesome and informative review. I was thinking of taking my P+ to the track so this is really really useful. THANK YOU.
     
  5. gg_got_a_tesla

    gg_got_a_tesla Model S: VIN P65513, Model 3 Res Holder

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    Great stuff, Doug_G! Love the profiles idea!

    One of my ICE-loving, "you-greens-are-idiots" friends has been challenging me to race against his Corvette at the Infineon Raceway in Sonoma. I'll keep the race to one lap ;) Or, take him to the neighboring drag strip instead. There are unfortunately no charging stations there, I believe.
     
  6. EdA

    EdA Model S P-2540

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    Roadster 3.0????
     
  7. Doug_G

    Doug_G Lead Moderator

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    It's no big secret that Tesla has promised a next-gen Roadster at some point. Probably will be based on the Gen III platform.
     
  8. efusco

    efusco Moderator - Model S & X forums

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    I had no idea that the power would fall off so fast on a track, very interesting information. Gotta wonder if there's a Track based Model S in the works, at least as a demo vehicle that would better address that sort of battery heating issue.
     
  9. eMileage

    eMileage Member

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    Thanks Doug. Another great post. I'll have to check out the other photos.
     
  10. EdA

    EdA Model S P-2540

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    Hmmm, it was with me! But i'm hanging out on the wrong topic, if I could get a Model S with 25% more range and 25% less performance....
     
  11. Desdi

    Desdi Member

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    What an awesome post, Doug_G! Thanks a bunch for sharing. And I really appreciate your elaborate desciption of the handling. Well done. icon14.gif
    I wonder if the P+ has a better cooling system. Bummer if not. All that extra handling goodness and you might only be able to use it for barely 2 laps before you have to take a break.
     
  12. stevezzzz

    stevezzzz R;SigS;P85D;SigX

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    I was talking to Michael Pettibone on Saturday; he's a performance driving instructor who spent a day at the track with a TMC member and his S last fall. He recalled that the performance fall-off became apparent already in the second half of the first hot lap. Since they were using the track's 14-50 charging port, the battery SOC was pretty high, too. Said he really enjoyed the S's performance up to that point, though, much more so than the Roadster.
     
  13. Shakespear

    Shakespear Member

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  14. Volker.Berlin

    Volker.Berlin Member

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    I guess it depends in part on how long the laps are on your particular circuit... ;-)
     
  15. Doug_G

    Doug_G Lead Moderator

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    The Shannonville Long Track is 4.03 km (2.5 miles).
     
  16. Doug_G

    Doug_G Lead Moderator

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    Oh - something I forgot to mention. I was unable to find a way to keep the parking brake off. I tried putting the car in neutral and turning it off. That was fine until I opened the door, and the car turned back on. And when I lifted my butt out of the seat the parking brake re-engaged. There must be an incantation for this...?
     
  17. brianman

    brianman Burrito Founder

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    Open the door before you put it into neutral. IIRC.
     
  18. Doug_G

    Doug_G Lead Moderator

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    Yeah, after typing my message I started wondering about that possibility. For some reason it didn't occur to me to try that at the track. Thanks.
     
  19. CapitalistOppressor

    CapitalistOppressor Active Member

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    Interesting. I can't imagine that a half ton battery pack is heating up quickly enough to be a problem, so it must be the motor or power electronics as you say.

    I wonder how much of it is just a software issue, with Tesla being unnecessarily conservative, and how much is a real engineering issue. The radiators are small, but so is the motor. It should be a solvable problem, unless the issue is with the power electronics. That would be a real trip if it turns out they need active cooling as well.

    Regardless, this just goes to show how high performance electric motoring is very much in groundbreaking mode. Historically, auto-racing has driven a large portion of the innovation in the ICE industry, and its time for those same reputational incentives to get to work on solving problems like this.
     
  20. yobigd20

    yobigd20 Well-Known Member

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    Maybe I missed this, what was the temperature outside during your run?
     

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