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R&T 360 Modena and Spider Road Test

Discussion in 'Technical Q&A' started by 4i2fly, Apr 23, 2004.

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  1. 4i2fly

    4i2fly Formula 3

    Apr 16, 2004
    1,333
    SF, Bay Area
    #1 4i2fly, Apr 23, 2004
    Last edited by a moderator: Sep 7, 2017
    Can someone tell me why there is a difference in speed between the two cars? The picture below shows the Spider tad slower than the Modena. Is it the test condition, drag, HP at the wheel, or extra 400 lb?

    Cheers,
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  2. Gary(SF)

    Gary(SF) F1 Rookie

    Oct 13, 2003
    3,637
    Los Altos Hills, CA
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    Gary B.
    #2 Gary(SF), Apr 23, 2004
    They clearly made a mistake, the Modena numbers are correct and the Spider numbers are not. They show the exact same gearing and RPM, the only other variable would be tire size, but we know they are identical, so the speed in gears at redline would in fact be identical also. It is a pure mathematical solution, and does not address acceleration times (which would be affected by the weight difference), etc, or whether either car could actually pull 8500 in 6th gear. Definitely a mistake.

    Gary
     
  3. 4i2fly

    4i2fly Formula 3

    Apr 16, 2004
    1,333
    SF, Bay Area
    #3 4i2fly, Apr 23, 2004
    Gary,

    You must know the equations and I have always wondered how they estimate the top end at the RPM. Please share the equation, and don't you think drag would be an effect for the top end. I only say this from watching races and as a result of more downforce for the bends the streight line speed is compromised.

    Matt
     
  4. Gary(SF)

    Gary(SF) F1 Rookie

    Oct 13, 2003
    3,637
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    #4 Gary(SF), Apr 23, 2004
    Matt -

    The equation is fairly complex, involving the rolling radius of the tire and the gearbox ratios as well as the final drive ratio. I don't have it front of me, someone like Mitch or Brian might chime in with it. Drag is of course a limiting factor in top speed and the Spider would have a bit more drag than the Modena. The extra weight would not be a factor in top speed but would of course affect acceleration.

    Gary
     
  5. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    9,742
    #5 Mitch Alsup, Apr 23, 2004
    I suspect the Modena was running a 275/40ZR18 rear tires while the spider was running a 275/35ZR18 rear tire. That is exactly the kind of difference one would expect with an aspect ratio change keeping the footprint width the same.
     
  6. 4i2fly

    4i2fly Formula 3

    Apr 16, 2004
    1,333
    SF, Bay Area
    #6 4i2fly, Apr 23, 2004
    The tires are identical for both at least what the two articles indicate. Modena was tested in August 1999 issue in Italy and Spider was tested July 2001 in US. Modena test car was a 6-speed manual while the Spider was F1-Paddle shifter. I am not sure if the test conditions could make that much difference. Modena was tested 70 F, 48% humidity, 350 ft elevation, wind calm and the Spider was tested at 84 F, 6% humidity, 150 ft elevation, and heavy wind. Could be the heavy wind. Don't know what to say!

    Cheers,
     
  7. Gary(SF)

    Gary(SF) F1 Rookie

    Oct 13, 2003
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    Gary B.
    #7 Gary(SF), Apr 23, 2004
    Weather conditions would make no difference to speed in gears. Might affect actual top speed, but they show the Spider reaching 8500 in 6th at too low a speed.

    Gary
     
  8. 4i2fly

    4i2fly Formula 3

    Apr 16, 2004
    1,333
    SF, Bay Area
    #8 4i2fly, Oct 23, 2004
    I may have figured why the R&T test car back in 1999 was faster than the R&T Spider in 2001. The fact is the 1999 being the euro version may have more hp and the 1999s are not eqipped with precats and 2ndary air pump which means a bit lighter than 2001 and a bit more free flowing exhaust and hp, but is that enough to make the difference in speeds between the two cars?
     
  9. Schatten

    Schatten F1 World Champ
    Owner

    Apr 3, 2001
    11,238
    Austin, TX
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    Randy
    #9 Schatten, Oct 23, 2004
  10. 4i2fly

    4i2fly Formula 3

    Apr 16, 2004
    1,333
    SF, Bay Area
    #10 4i2fly, Oct 23, 2004
    Thanks for the link, I plugged the numbers and they come out identical to R&T if the RPM is set to 9000, amazing!
     

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