News

360 CS Top-speed & Gearing

Discussion in '360/430' started by thomas_b, Dec 15, 2003.

  1. thomas_b

    thomas_b Formula Junior

    Sep 15, 2003
    765
    we did have some discussion about the 360 top-speed and gearing some time ago which confused me – I played a little with Excel over the weekend – formula: speed [mph] = ((RPM [1/min] / trans. Ratio) * 60) / Tire Rev’s per mile [1/mile] -

    results are attached for your happy consumption:
     
  2. thomas_b

    thomas_b Formula Junior

    Sep 15, 2003
    765
  3. spyderman

    spyderman Formula 3

    Nov 4, 2003
    1,436
    Toronto - Canada
    Full Name:
    Spyderman
    Thomas:

    Great info. I wonder how Auto Car got a top speed like 192 + MPH out of the Stradale they tested when the gearing on the car only allows the car to go max 176 MPH?? I guess you can not believe everything you read!

    It seems the Car & Driver story in Jan/04 was correct when they also got the Stradale to 176 MPH.
     
  4. thomas_b

    thomas_b Formula Junior

    Sep 15, 2003
    765
    the numbers are heavily dependent on the tire size parameters – I have checked several tire calculators on the Web to determine the Tire Revs/min and have taken the pessimistic approach, I,.e. max speed varied from 174 to 180mph (8.5K RPM) in my calcualtions

    a bunch of useful calculators are @ http://www.csgnetwork.com/automotiveconverters.html
     
  5. thomas_b

    thomas_b Formula Junior

    Sep 15, 2003
    765
    best value calculation:
     
  6. thomas_b

    thomas_b Formula Junior

    Sep 15, 2003
    765
  7. Artherd

    Artherd F1 Veteran

    Jun 19, 2002
    6,587
    Bay Area, CA
    Full Name:
    Ben Cannon
    Does the 360 rev to 8750 fuel cutout despite having a tach red at 8500 like the F355 did?

    That could account for some spread.
     
  8. dan360

    dan360 F1 Rookie

    Feb 18, 2003
    2,669
    Boston
    Yep - 360 Cut out is circa 8800 rpm. I'd be interested in seeing the table with 8800 rpm as the max revs.

    A friend in the UK actually did VMAX his 360 in Belgium. Not that this is possible in MA, but its interesting to know.
     
  9. jim g

    jim g Formula Junior

    Jan 8, 2003
    786
    Waverly, Pa.
    Full Name:
    Jim Gress
    So is the 360 CS geared lower then the standard 360?
     
  10. Gary(SF)

    Gary(SF) F1 Rookie

    Oct 13, 2003
    3,637
    Los Altos Hills, CA
    Full Name:
    Gary B.
    No. It's the difference in tire diameter that is accounting for the top speed difference - and max speed in all gears for that matter. The 360 has a larger overall diameter tire than the CS.

    Gary
     
  11. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    6,335
    My F355 hits fuel cut off at 9,200--but don't ask me how I know.
     
  12. thomas_b

    thomas_b Formula Junior

    Sep 15, 2003
    765
    correct - unfortunately the numbers vary from calculator to calculator

    >>regarding max RPM
    my 360 CS cuts out at 8658 RPM - this might vary from car to car but i don't think a lot
     
  13. Gary(SF)

    Gary(SF) F1 Rookie

    Oct 13, 2003
    3,637
    Los Altos Hills, CA
    Full Name:
    Gary B.
    How did you determine the number so exactly?

    Gary
     
  14. jim g

    jim g Formula Junior

    Jan 8, 2003
    786
    Waverly, Pa.
    Full Name:
    Jim Gress
    Since the 360 CS's tire and wheel diameter is larger then the 360's wouldn't that give it a higher overall gearing and top speed?
     
  15. Gary(SF)

    Gary(SF) F1 Rookie

    Oct 13, 2003
    3,637
    Los Altos Hills, CA
    Full Name:
    Gary B.
    Yes, if that were a true statement. The CS has larger wheels (19" vs 18") but lower profile tires (285/35 vs 275/40). If you look at the actual diameters, the 18" tires on the 360 are larger than the 19" tires on the CS.

    Gary
     
  16. thomas_b

    thomas_b Formula Junior

    Sep 15, 2003
    765
    I am looking into installing the SPA 3-stage shift light stuff - we did some test installation and comparisons - last digit in the max RPM number is probably BS – however though it would indicate “my number” if taken as measured

    More info on the SPA kit

    - summary of features
    http://www.bimmerworld.com/html/spa-technique-3-stage-shift-light.htm

    - manual
    http://www.merlinmotorsport.co.uk/shift%20light%203.1%20manual.htm

    if someone has a good tip where to place the LEDs – speak up – I want to avoid to modify the stock dash/wheel so options are limited
     
  17. dan360

    dan360 F1 Rookie

    Feb 18, 2003
    2,669
    Boston
    Another factor to consider here is expansion of air/tyres @ temperature (why of course the racers use Nitrogen in the tires is to make this expansion more predicatable thru removal of moisture).

    Perhaps a physicist here might comment on this factor... 3% = 5 or 6mph...

    On the rev limit I've certainly seen an indicated 8800 revs in my car when it hits the limiter. Obviously I'm not sure of the absolute accuracy of the gauge.
     
  18. thomas_b

    thomas_b Formula Junior

    Sep 15, 2003
    765
     
  19. dan360

    dan360 F1 Rookie

    Feb 18, 2003
    2,669
    Boston
    So a press car 360CS with an 8800 limiter + 4% tyre growth at max speed would do more or less 194mph...

    NB I've seen the redline in 5th in my car and that was circa 155 or so - wasn't really concentrating on the speedo at the time :)
     

Share This Page