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Thread: Viper ACR smokes race cars and super cars all the same

  1. #21
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    Wrecking the production car lap record at Mazda Raceway Laguna Seca

    Telemetry data for those interested.

    Billy/Stuntman,

    Would you mind elaborating on how track conditions affect laptimes?

    In my limited HPDE experience, using Thill as an example, I've noticed that cool days lead to the fastest laps running towards the end of the day where as on hot days, the 2nd morning session is generally the fastest. In the afternoon on hot days, I feel like I'm putting more effort into the driving only to be going a second a lap slower. So is there a balance between the track rubbering in vs the temps?

  2. #22
    Senior Member bellwilliam's Avatar
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    Quote Originally Posted by RobertR1 View Post
    Wrecking the production car lap record at Mazda Raceway Laguna Seca

    Telemetry data for those interested.

    Billy/Stuntman,

    Would you mind elaborating on how track conditions affect laptimes?

    In my limited HPDE experience, using Thill as an example, I've noticed that cool days lead to the fastest laps running towards the end of the day where as on hot days, the 2nd morning session is generally the fastest. In the afternoon on hot days, I feel like I'm putting more effort into the driving only to be going a second a lap slower. So is there a balance between the track rubbering in vs the temps?
    you didn't ask me, but my Trackhq post counts qualifies me:

    you want coldest air for max power. but track surface needs to be ~70F for optimum grip.
    so ideal lap is at ~50F weather with sun out on track for few hours already (noon-2pm). warming up track surface.

    if at Willow Springs. it often gets very windy in the afternoon. so it is often slower (no matter which way wind blows, it is almost always slower than no wind) in the afternoon even is weather condition is better.

    at desert tracks. in the summer, although first session should be fastest due to weather. But because of dust (from overnight) on track at first session (often red session), it won't be fastest after a couple of sessions to clean up the track.

    at ACS, lap time depends on where they put the cones. nothing to do with skill or weather
    Last edited by bellwilliam; 11-09-2015 at 12:56 PM.
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  3. #23
    enjoys driving fast Jack Olsen's Avatar
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    Yeah, it's a cheater tire -- not a real V720 at all. But who cares? Those times are incredible for a street car. Just awesome.

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    Thanks Bell!

    What about the track 'rubbering in' how does that effect laptimes over a weekend?

    Let's say the ideal conditions you listed persist throughout a race weekend. Would the track be noticeably faster from friday morning to sunday afternoon?

  5. #25
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    Quote Originally Posted by RobertR1 View Post
    Wrecking the production car lap record at Mazda Raceway Laguna Seca

    Telemetry data for those interested.

    Billy/Stuntman,

    Would you mind elaborating on how track conditions affect laptimes?

    In my limited HPDE experience, using Thill as an example, I've noticed that cool days lead to the fastest laps running towards the end of the day where as on hot days, the 2nd morning session is generally the fastest. In the afternoon on hot days, I feel like I'm putting more effort into the driving only to be going a second a lap slower. So is there a balance between the track rubbering in vs the temps?
    Weather and track conditions can cause significant discrepancies in lap times. You can lose SECOND(S) between early in the morning vs. the middle of the day, which causes track temps and tire temps to be outside of their ideal operating range. Also depending on if the track is 'rubbered in' from a lot of cars on track or 'green' -long periods of no one on the track and after rain, can cause further time differences.

    This is why most magazine comparisons are in most cases useless. The same car can be 1-2 seconds slower in the afternoon than the morning. So if you're comparing two similar in performance cars, depending on when each car ran can greatly affect the outcome.

    Same goes for the tire conditions. If you have a BMW M4 and C63 that were long-term test cars with 5,000 miles on their tires and a ATS-V with brand new tires, the ATS could have a 1-2 second advantage over the M4/C63. Run the ATS in the morning and other two in the afternoon and there could be as much as a 2-4 second disparity.

    On top of that, driver experience comes into play. If, say a Z06 with a ton of downforce is easy to drive, but a pro is 0.5 seconds faster in a Viper (with less aero) than the Z06, but your average journalist is 1 second faster in the more stable Z06... which figure do you want to know or care about?

    For the "Lightning Lap" competition, it's spread over multiple days with multiple drivers of varying experience. If the M3 & C63 are within a second of eachother with a pro driving, LL could see 2-3-4 second disparity if joe-blow drives the M4 and joe-average-trackday-guy drives the C63 (faster).


    ...So there are more variables than you can imagine and magazine competitions/comparisons are usually not definitive and often very erroneous. You need to back to back two cars by a pro with each car having a new set of tires, early in the morning, as close to back to back in lap time (hop out of one and into the other) to have a truly accurate comparison. Most magazines dont do this..


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    Thanks Billy! Would love to see an independent study done demonstrating this. It'd be eye opening for car enthusiasts to see that. Credit to those mags who might do it the right way. They should really advertise that element. I can't think of any off the top of my head.

  7. #27
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    Some may do it. Most readers don't care, they just want #s to argue over.

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