Anybody kow the Cda od a 205
  • Register
  • Help
Results 1 to 20 of 20
  1. #1
    1000+ Posts parry's Avatar
    Join Date
    Sep 2002
    Location
    Sydney Australia
    Posts
    1,326

    Default Anybody kow the Cda od a 205

    Need the aerodynamic efficiancyof a 205 also the rolling resistance. Need this for my new data logger.

    Advertisement


    Peter T, canyou please send me the gearratios for my gearbos, it was the same as yours I think.
    90 205 Gti Cherry Red(Track Car)
    2009 207gti
    1985 505gti (Shitbox Rally) Sold

    PBs:

    Oran Park: 1:27:9
    Wakefield: 1:05.6 (July 2015)
    Eastern Creek: 1:54 (8v) 1:48 (16V)
    Mt Huntley: 34.44 (2004 stock 205)
    Ringwood: 35.06 (30/10/2005)
    Winton: 1:33.6 (2017)

  2. #2
    1000+ Posts parry's Avatar
    Join Date
    Sep 2002
    Location
    Sydney Australia
    Posts
    1,326

    Default

    Cda for a 205 is 0.34
    90 205 Gti Cherry Red(Track Car)
    2009 207gti
    1985 505gti (Shitbox Rally) Sold

    PBs:

    Oran Park: 1:27:9
    Wakefield: 1:05.6 (July 2015)
    Eastern Creek: 1:54 (8v) 1:48 (16V)
    Mt Huntley: 34.44 (2004 stock 205)
    Ringwood: 35.06 (30/10/2005)
    Winton: 1:33.6 (2017)

  3. #3
    1000+ Posts U Turn's Avatar
    Join Date
    Jan 2004
    Location
    Adelaide
    Posts
    1,761

    Default

    Parry, does your data logger need the frontal area as an input as well?
    Take the long way home....

    - 306 gti6

  4. #4
    1000+ Posts parry's Avatar
    Join Date
    Sep 2002
    Location
    Sydney Australia
    Posts
    1,326

    Default

    no frontal area needed. it must calculate it from the cda.

    the data logger i have is a dl90 (google it). its an impressive logger. has track mapping, sector times, several inputs and all power calculations.
    90 205 Gti Cherry Red(Track Car)
    2009 207gti
    1985 505gti (Shitbox Rally) Sold

    PBs:

    Oran Park: 1:27:9
    Wakefield: 1:05.6 (July 2015)
    Eastern Creek: 1:54 (8v) 1:48 (16V)
    Mt Huntley: 34.44 (2004 stock 205)
    Ringwood: 35.06 (30/10/2005)
    Winton: 1:33.6 (2017)

  5. #5
    1000+ Posts U Turn's Avatar
    Join Date
    Jan 2004
    Location
    Adelaide
    Posts
    1,761

    Default

    Then the Cd figure input can't be what was said earlier i.e 0.34 etc. I'm assuming the data logger uses it to work out drag and hence top speed etc? If so, then the formula for aerodynamic drag is 0.5 x Cd x (air density) x (Frontal area) x (velocity squared). Air density is around 1.2 kg/m^3, and you know velocity so the only things needed are Cd and frontal area.

    I think the Cda that it's asking for is actually Cd x a, where a is the frontal area and Cd = 0.34. I don't think cda = 0.34, but cd instead.
    Take the long way home....

    - 306 gti6

  6. #6
    1000+ Posts PeterT's Avatar
    Join Date
    Jul 2000
    Location
    Castle Hill, Sydney
    Posts
    7,446

    Default

    2.923
    1.85
    1.36
    1.069
    0.866

    4.43:1 diff

    '92 205 Mi16
    '90 Mi16x4

  7. #7
    Fellow Frogger!
    Join Date
    Sep 2003
    Location
    Adelaide
    Posts
    409

    Default

    1986 Peugeot 205 GTi

    Drag coefficient: 0.34
    Frontal area: 1.78
    Cx: 0.61


    help me out here Jude, but i think that means Cd = 0.34 but the CdfA is 0.61

    '04 Citroen Xsara VTS

    Mallala - 1:29.96

  8. #8
    1000+ Posts U Turn's Avatar
    Join Date
    Jan 2004
    Location
    Adelaide
    Posts
    1,761

    Default

    Yeah well 0.34 x 1.78 = 0.61 so it makes sense. Yeah I checked around on the net a bit and confirmed that cda definitely is cd x frontal area, so if the data logger requires cda, then you should enter in 0.61 (as long as that frontal area is correct).

    Let us know what kind of results you get parry and how it compares to when you get it out on the track etc. I'm very interested.
    Take the long way home....

    - 306 gti6

  9. #9
    1000+ Posts parry's Avatar
    Join Date
    Sep 2002
    Location
    Sydney Australia
    Posts
    1,326

    Default

    Thanks peter.

    Thank you too Jas, it is Cda. So 0.61 is it.

    Now I need to measure the rolling circumfrance of my wheels, in meters.

    185x60x14 any takers on a guess
    90 205 Gti Cherry Red(Track Car)
    2009 207gti
    1985 505gti (Shitbox Rally) Sold

    PBs:

    Oran Park: 1:27:9
    Wakefield: 1:05.6 (July 2015)
    Eastern Creek: 1:54 (8v) 1:48 (16V)
    Mt Huntley: 34.44 (2004 stock 205)
    Ringwood: 35.06 (30/10/2005)
    Winton: 1:33.6 (2017)

  10. #10
    1000+ Posts U Turn's Avatar
    Join Date
    Jan 2004
    Location
    Adelaide
    Posts
    1,761

    Default

    (60/100) x 185 x 2 + (14 x 25.4) = 577.6mm = 0.578 metres.
    Take the long way home....

    - 306 gti6

  11. #11
    Fellow Frogger!
    Join Date
    Sep 2003
    Location
    Adelaide
    Posts
    409

    Default

    times pi


    circumference = pi * diameter

    circumference = pi * 577.6mm
    circumference = 1814.58 mm

    '04 Citroen Xsara VTS

    Mallala - 1:29.96

  12. #12
    1000+ Posts U Turn's Avatar
    Join Date
    Jan 2004
    Location
    Adelaide
    Posts
    1,761

    Default

    Lucky Quentin didn't leave his brains behind.

    Sorry Parry, what I gave you was just the diameter. Quentin did the rest of it, and his answer is the right one.
    Take the long way home....

    - 306 gti6

  13. #13
    1000+ Posts parry's Avatar
    Join Date
    Sep 2002
    Location
    Sydney Australia
    Posts
    1,326

    Default

    Luckyyou guys are around, I would be lost.

    Thanks a million

    I will post some graphs is you are intrested after Saturdays event. Let me know if there is anything particular you would like to see.

    I know my car has 62kw ATW from a dyno run, would be intresting how close the logger can get.
    90 205 Gti Cherry Red(Track Car)
    2009 207gti
    1985 505gti (Shitbox Rally) Sold

    PBs:

    Oran Park: 1:27:9
    Wakefield: 1:05.6 (July 2015)
    Eastern Creek: 1:54 (8v) 1:48 (16V)
    Mt Huntley: 34.44 (2004 stock 205)
    Ringwood: 35.06 (30/10/2005)
    Winton: 1:33.6 (2017)

  14. #14
    1000+ Posts PeterT's Avatar
    Join Date
    Jul 2000
    Location
    Castle Hill, Sydney
    Posts
    7,446

    Default

    Don't forget the rolling radius, or revs/km will differ to the theoretical diameter. You'd need to check a tyre web site.

    '92 205 Mi16
    '90 Mi16x4

  15. #15
    1000+ Posts U Turn's Avatar
    Join Date
    Jan 2004
    Location
    Adelaide
    Posts
    1,761

    Default

    Peter, why's that? Is it due to the sidewall slightly compressing? Would it really differ that much from the theoretical diameter?
    Take the long way home....

    - 306 gti6

  16. #16
    Fellow Frogger!
    Join Date
    Sep 2003
    Location
    Adelaide
    Posts
    409

    Default

    should parry be doing a chalk-line walk. where you draw a chalk line on the ground and on the tyre and then drive one revolution and mark the ground again. I would have thought the theoretical circumference was still the same under flex - it is belted after all.

    Those data loggers are fancy things... i love it how they can draw a map of the track just from measuring g-forces.

    '04 Citroen Xsara VTS

    Mallala - 1:29.96

  17. #17
    1000+ Posts parry's Avatar
    Join Date
    Sep 2002
    Location
    Sydney Australia
    Posts
    1,326

    Default

    This logger also uses GPS for positioning. I have also hooked up the RPM pickup and also the brake light to see where I am braking.

    It also calculates the gear you are in and all HP figures. I can also hook up analogue inputs like temp, throttle position etc.

    The main reason we purchased it is we share the car between 2 drivers and with the data logger we can see where one driver is faster than the other on the track.
    90 205 Gti Cherry Red(Track Car)
    2009 207gti
    1985 505gti (Shitbox Rally) Sold

    PBs:

    Oran Park: 1:27:9
    Wakefield: 1:05.6 (July 2015)
    Eastern Creek: 1:54 (8v) 1:48 (16V)
    Mt Huntley: 34.44 (2004 stock 205)
    Ringwood: 35.06 (30/10/2005)
    Winton: 1:33.6 (2017)

  18. #18
    1000+ Posts U Turn's Avatar
    Join Date
    Jan 2004
    Location
    Adelaide
    Posts
    1,761

    Default

    That's amazing. If you don't mind me asking, how much do one of these cost?
    Take the long way home....

    - 306 gti6

  19. #19
    1000+ Posts parry's Avatar
    Join Date
    Sep 2002
    Location
    Sydney Australia
    Posts
    1,326

    Default

    Quote Originally Posted by jastanis
    That's amazing. If you don't mind me asking, how much do one of these cost?
    I bought it second hand from the manufacturer as they are doing trading deals on the new loogger the DL1. The DL1 has video sync as well ans omething like 15 various inputs.

    The second hand DL90 cost me about $800 delivered.
    90 205 Gti Cherry Red(Track Car)
    2009 207gti
    1985 505gti (Shitbox Rally) Sold

    PBs:

    Oran Park: 1:27:9
    Wakefield: 1:05.6 (July 2015)
    Eastern Creek: 1:54 (8v) 1:48 (16V)
    Mt Huntley: 34.44 (2004 stock 205)
    Ringwood: 35.06 (30/10/2005)
    Winton: 1:33.6 (2017)

  20. #20
    Fellow Frogger!
    Join Date
    Sep 2003
    Location
    Adelaide
    Posts
    409

    Default

    i have some video footage of DSR racers in europe and america fitted with the synchronised data loggers. It is absolutely amazing to see the telemetry overlayed over the screen and you can actually see from a first person perspective where the fastest line was.

    Hopefully in a few years, * start dream....

    '04 Citroen Xsara VTS

    Mallala - 1:29.96

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •