What is the fastest you've ever driven and what car?

Discussion in 'The Guru's Pub' started by FULMTL, Jul 16, 2012.

  1. MM10X

    MM10X Ancient Guru

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    Its a mostly stock MX83, 7M-GE with stock A340E 4speed automatic.
    I changed the head gasket, cleaned up the top end of the engine about two years ago and put a better air filter on it. Since then just regular oil changes.

    Suspension shocks have been replaced, springs where cut for 1" drop. Stock other than this.
    I still need to put bigger sway bars on it, lots of body roll even after dropping it.

    old tyres @ 35psi.
    Its quite a "slow" accelerating car, 0-60 can barely get 10 seconds with a hard launch due to gearing. After you get over 90 it pulls harder than a lot of other cars in its class.

    Next upgrade would be a 7MGTE and 5 speed, or just a 5-speed. As I currently have a project car its just the daily until I blow the engine.(Never going to happen.)
     
  2. scheherazade

    scheherazade Ancient Guru

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    Mass matters a lot in acceleration, but not much in top/sustained speed.

    Mass affects the energy required to accelerate at a given rate.
    (energy = 0.5 mv^2, where the engine produces X watts, so the time taken to accelerate is nominally (Ev1-Ev0)/watts. Notice also that M is O(1), and V is O(2), i.e. the speed you want to hit nevertheless matters more than the mass you want to accelerate.)

    Top speed is limited by the increasing effects of drag as speed increases.
    Drag, at a given rate, will produce a negative energy rate that you have to overpower in order to keep producing acceleration.

    Mass creates rolling resistance due to how it deforms the tyre, but with stiff sidewalls and good tyre pressure, you can actually make a heavier car have less rolling resistance than a lighter car.

    As speed goes up, the major drag component becomes air resistance.
    So much so, that all other drag factors become little more than rounding errors in comparison.

    Essentially, as you accelerate, at any given instant, you start out limited by : HP vs Weight
    In the end, your top speed is limited by : HP vs Aero-drag

    And you see this in many super-cars. As HP goes up dramatically, top speed only inches up.






    Then there is another factor : Torque, and gearing.

    You can have 100000 Hp and 100000 lb-ft of torque.
    But if you redline in top gear at 150 mph, you're not going to go any faster than 150 mph...

    Or if your torque curve maxes at 4000 rpm, and falls off after that, then as you accelerate past 4000 rpm, you start accelerating slower and slower, until the air resistance overpowers the motor.





    Weight and handling are also not directly related.
    Tyres also get more traction as weight increases.
    Tyres do become overloaded, and when overloaded they lose traction.
    You can buy tyres meant to grip and handle a heavy car.

    Generally, a set of grippy tyres will turn any tub into a sh1t hot roadholding monster.
    The problem becomes that heavy cars eat tyres like they're going out of style.
    If I took the GTR to VIR and flogged it hard, I'd go through a set of new tyres and brakes in less than a day.
    In comparison, an Elise would do multiple track days.

    Other factors affect handling.

    A light car that is top heavy will handle like poo.
    A heavy car that is bottom heavy will handle pretty well.

    Dampers/Sways allow you to better change direction without causing the car to unsettle, but they don't determine your max sustained G force.
    (You can use hard sways to deliberately overload the outside rear tyre to reduce traction in back, to help FWD cars not understeer.)

    You can run a lot of toe out in the front to make the car eager to turn in.
    You can run some toe out in back to help prevent understeer (as needed : i.e. can cause RWD to go tail happy).
    You can increase your -camber to help sustained cornering.
    You can decrease your -camber and increase your caster to help straight line braking while not sacrificing cornering.
    But all these options also make you eat tyres faster. (They also lower your top speed, other than the caster)

    The GTR is heavy enough that I choose to compromise the performance of my alignment to improve longevity.

    With a lighter car, I could run aggressive alignment settings without suffering on longevity.





    But TBH, who cares.
    A civic is fast enough to put you into jail, and on a track tyres matter more than anything.





    Yes. Lol, I wish it was an Ultima GTR...
    The car is pretty nice, but I'm not the car. Just another nobody like all the rest.



    Still have the GTR.
    Evo and 335 are sold.
    Miss the evo, though.
    Nowadays looking at a cobra or lotus 7... or the RCR SL-C Ultralite Coupe.
    The Cobra/7 would be great for autocross.
    The SL-C should be good too, but more of a circuit car.
    I only autocross, so I'm thinking Cobra/7 would make more sense.

    -scheherazade
     
    Last edited: Aug 10, 2012
  3. Pill Monster

    Pill Monster Banned

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    ^I once owned a Cadillac Fleetwood, thing musta weighed about 2 ton....even with a 5.7L engine it was like driving a tank.

    Needed all that horsepower just to take off from the traffic lights hahaha
     
    Last edited: Aug 10, 2012
  4. powerspec

    powerspec Active Member

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    1st car: 2002 Ford Ranger XLT 4.0L V6...... 90MPH (limited top speed)
    2nd car: 2007 Chevy Malibu LT 2.2L I4...... 110MPH (limited top speed)
    Current car: 2012 Fiat 500 Sport 1.4L I4.... 170km/h (car is set to metric and limited to 170km/h)

    Fastest I've ever ridden in a road legal car, 2003 Mitsubishi Eclipse GTS 3.0L V6.... 140MPH
     
    Last edited: Aug 10, 2012

  5. Romo

    Romo Master Guru

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    190 km/h in my old ยด92 Merc w201 190e ;)
     
  6. kens30

    kens30 Maha Guru

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    About 270 km in my friends custom build turbo lancia around 500hp if i remember correctly (not sure which model) but this speed freaked me out and i slowed down.The road all of sudden seemed to shrink and couldn't see clearly.
     
  7. Subaru Swift

    Subaru Swift Master Guru

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    over 150mph in my old scooby sti v4 on a race track in the uk, but it was more fun in the bends then top end speeds..... :)
     

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