Effect of Ambient Tenperature on Lap Times | FerrariChat

Effect of Ambient Tenperature on Lap Times

Discussion in 'Tracking & Driver Education' started by Crawler, Oct 22, 2014.

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  1. Crawler

    Crawler F1 Veteran

    Jul 2, 2006
    5,018
    #1 Crawler, Oct 22, 2014
    Last edited by a moderator: Oct 22, 2014
    I have now done eleven track days at Carolina Motorsports Park. My two overall fastest lap times have been 1:57.4 (11-19-13) and 1:57.8 (10-21-12). Both of these were done under relatively low ambient and track temperatures.

    My most recent track day was last Saturday (10-18-14). Ambient temperature was in the upper 70s under very bright and warm sunshine. My three fastest laps were set at the end of the final session (around 3:30 PM) when temperatures were about at their peak. The times were 2:00.7, 2:00.6, and 2:00.6.

    My question is this. Can a substantial difference in ambient and track temperature alone account for the 3+ second lap time delta on a 2.4 mile track? I really felt good about the laps, corner entry speeds, etc. and was surprised to see that I didn't crack the two minute mark. I also felt good about my speed relative to other cars; in other words, had I been in the 1:57s this last time out, I would have been very competitive with cars that should be faster than mine, so it did seem as though everybody was slower.

    A three second variance seem like a lot to me, but the evidence would seem to indicate that it's due to the difference in temperature. I should add that all of these sessions were done with the same specifications, tire type, etc. The car is a Volkswagen GTI Mk. 6. Input is appreciated.
     
  2. gatorgreg

    gatorgreg Formula 3

    Dec 13, 2004
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    The short answer is yes. The reasons for your 3 second gain could be attributed to other factors (track condition, tires, air density, the list is long.)
    I am assuming CMP is an all asphalt track. If so, I would assume 1 to 1 1/2 seconds is lower temperature of the track surface and the rest was in your head. Meaning you are driving better.
     
  3. Ney

    Ney F1 Veteran
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    Apr 20, 2004
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    There is a reason that late afternoon when the sun is starting to set is called "Happy Hour" at Indy. Track cools and air density increases....more grip + more HP = faster lap times.
     
  4. ProCoach

    ProCoach F1 Veteran
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    Sep 15, 2004
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    Peter Krause
    No, not three seconds, especially when your "slower" session was still in conditions most would find optimal. Without data to compare, you are just guessing! <grin>

    That said, as tracks age, and the surface becomes more polished and worn, the differential between "fast" laps (cool, morning, low humidity) and "slower" laps (hot, afternoon, high humidity) widens substantially.

    I would posit that the track's age and general end-of-life (the aggregate at this track, except for T13 and inside T14, is SIXTEEN years old, way beyond the norm for falloff) have contributed more to your lap time fall off than any other single issue.

    Time for you to buy something simple and self contained. An Aim Solo would be enough to answer this question definitively.
     
  5. Crawler

    Crawler F1 Veteran

    Jul 2, 2006
    5,018
    Thanks Peter. I will check into the Aim Solo. I've tried a couple of other systems and found them less than satisfactory. I had not considered long-term surface deterioration, but that certainly fits the scenario.
     
  6. ProCoach

    ProCoach F1 Veteran
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    I can see one and a half to two seconds, Dan. But the AiM Solo, for less than $400, would tell you everything you need. Be glad to help.
     
  7. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    26,294
    socal
    Tires, fuel load, chassis set-up!
     
  8. gatorgreg

    gatorgreg Formula 3

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    The AIM solo would be a great investment.
     
  9. Crawler

    Crawler F1 Veteran

    Jul 2, 2006
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    I'll probably go back in late November. Trying to talk myself into coughing up 400 bucks for the AIM solo. Will likely do it.
     
  10. speedsport

    speedsport Formula Junior

    Mar 14, 2013
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    Michael
    For what it's worth, I've never seen a road course produce faster lap times around 3PM. That time is usually when the sun is adding the most heat into the track, and the track is full of other rubber and debris from cars running on it all day.

    In all my racing, afternoon sessions, say 1-4 pm are almost always slower then AM or sessions after 4 pm. Now that's a general statement with tons of other factors, but as a general rule, that's the case.

    On the other hand, 3PM in October is much different then 3PM in July. The sun angle plays a huge part in track conditions.

    3 seconds is a lot of varience due to time of day / ambient temps. I'd look elsewhere for the reason.
     
  11. chris1866

    chris1866 Formula Junior
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    Another +1 for the AiM Solo. If your car is new enough, the SOLO DL is an even better bet if you want to get some serious data. That can interface with the car's ECU via the CAN bus and give you all sorts of data (throttle position, brake pressure, etc.)
    If you have someone (like Peter) who has the knowledge/ability to translate that data and help you apply it, it can be a great learning tool.
     
  12. ProCoach

    ProCoach F1 Veteran
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    I'm always glad to talk people through the installation of these wonderful tools. I send them out pre-configured for the purchaser's application, too.
     
  13. CornersWell

    CornersWell F1 Rookie

    Nov 24, 2004
    4,874
    3 seconds is an ETERNITY on a race track. Would agree with ProCoach that temperature isn't likely the only factor.

    CW
     
  14. Crawler

    Crawler F1 Veteran

    Jul 2, 2006
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