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A journey with Punto

Discussion in 'Punto 1.3 MJD' started by shams, May 21, 2011.

  1. Ganges

    Ganges Esperto

    Messages:
    3,121
    Driver Seat _/
    :
    Grande Punto 1.3
    shams,
    have you seen that pic(though its all yours),the needle was on 180....:eek:
    is it possible with 75Hp,mine was struggling after 145Kmph...
  2. ENKI

    ENKI Esperto

    No way FGT should sound stressed at that speed. Yep, it sounds loud IMO but progress is fine till 160 km/hr.
    By the way, Does that 15 inch wheel correct some of the speedo error? Max. speed could be 175 km/hr in your E Pack because of bigger RIM size but that should be equally fast.
  3. shams

    shams Esperto

    Messages:
    2,388
    Bangalore
    @ganges, even i was surprised to see 180 on the speedo that day as the previous best was 175, that too with long empty stretch and single occupant.
    this time i ran out of road otherwise it could have gone little more.
    car is opening up more n more with every mile clocked.

    everything said i would like to admit that i am not going to try it again till i upgrade to fatter tyres.
    recently saw that this profile has max speed limit of 180.
    1 person likes this.
  4. ENKI

    ENKI Esperto

    Aerodynamics & drag coefficient immediately comes into play when you start climbing over 140 km.hr. With every 10 km/hr increase further, airdrag becomes more & more dominant exponentially. The additional 10 Km/hr can easily be attributed to that. If you had the strong wind blowing opposite to your direction of travel, that's not a surprise. On the other hand, it could be opposite. What else, above 100 km/hr, 60% of the engine efficiency is utilized for fighting Air Drags. At 70 miles per hour (112.7 kilometers per hour), there's four times more force working against the car than at 35 miles per hour (56.3 kilometers per hour). Improvement in drag coefficient has yielded around 60% gain in fuel economy gains during last 50 yrs if exclude other factors (like engines, tyres etc).

    Also sometimes it could be attributed too high revving for diesels. Handover it to 5 th gear asap if you are aiming to take it to max. But this thing won't make noticeable difference. Yes, Air drag is a very big factor & may even cause the same car to feel exhausted@150 km/hr. I have felt my 90 HP losing breath@175 km/hr while at other times i have accidentally found myself touching 190 km/hr & then slowed down intentionally where i could try further:mrgreen:.
    Nothing to feel worry or happy about..!

    Automobile drag coefficient - Wikipedia, the free encyclopedia
  5. ENKI

    ENKI Esperto

    Guys, That due to Air Drag. At higher speeds, Drag coefficient becomes dominant exponenially. Engine performance & mileage could be improved by as much as 60% by controlling Cd of a car. If there was a strong wind blowing against the car, it could very well limit it's top speed by as much as 20-30 km/hr. However, if it favoring, you may get an additional boost at such speeds. So don't worry, not an issue.
  6. sungoa2010

    sungoa2010

    Messages:
    2,878
    Goa
    +1 the slope of the road also matters
  7. shams

    shams Esperto

    Messages:
    2,388
    Bangalore
    I am planning the following changes in punto's footwear in another three weeks probably:
    - 195/65 R15 Michelin Primacy LC tyres : 5500-5900 per tyre (depending on which shop I buy from)
    - Linea (active, dynamic) steel rims : 970 per rim
    - Linea wheel cover : 388 per rim.

    Wanted to go for alloys but budget is a problem right now and have to change the tyres soon as two of them have worn out badly. Will be switching to alloys sometime in future.

    Have zeroed in on Michelin PLCs after going through various reviews available on the internet.
    Have selected 65 profile since it gives 10mm additional GC although i have never felt the GC to be low but better GC is always desirable.
  8. Ganges

    Ganges Esperto

    Messages:
    3,121
    Driver Seat _/
    :
    Grande Punto 1.3
    shams,
    i think active model has better GC then emotion or emotion pack ?
    also i seen the sales guys saying emotion has better GC than active dynamic ? with tires profiles of 195/60/R15 it was totally wrong to my sense.
    if i assume with your current tires of 165/80 R14 and managing to change with 195/65 R15 then the GC is reduced by 5mm... ;)

    Though i'm very much interested in 195/65 R15 for my future change(will follow your thread) also gives me raised GC of 0.98 cm above 195/60 R15 ;)
    Last edited: Apr 21, 2012
  9. shams

    shams Esperto

    Messages:
    2,388
    Bangalore
    Ganges, its correct that Active/Dynamic have better GC compared to EP but the difference due to tyre profile is just 2.3 mm, thats all.

    Have a look at the below calculations:
    If we calculate distance to ground from center of tyre also commonly know as 'rolling radius':

    For Active/Dynamic:
    (165*.8*2 + 14*25.4)/2 = 309.8

    For EP (current Emotion)
    (195*.60*2 + 15*25.4)/2 = 307.5

    With 195/65 R15 tyres
    (195*.65*2 + 15*25.4)/2 = 317.25

    Note:
    -1 inch = 25.4 mm
    -sidewall height is calculated as below:
    e.g. for 165/80 it is 165*.8 = 132 mm

    Hence by changing stock tyres to 195/65 R15 profile tyres:
    Active gets 317.25 - 309.8 = 7.45 mm more GC
    EP gets 317.25 - 307.5 = 9.75 mm more GC
    Last edited: Apr 21, 2012
    1 person likes this.
  10. sungoa2010

    sungoa2010

    Messages:
    2,878
    Goa
    My doubt is about the odo calibration. Which size is taken to calibrate odo. I think the odo and speedo meters are not adjusted differently in different variants.

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