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Formula 1 - 2 stroke vs 4 stroke engines

Discussion in 'Other Off Topic Forum' started by Kenny94945, Nov 12, 2003.

  1. Kenny94945

    Kenny94945 Karting

    Nov 1, 2003
    145
    Marin Calif
    Hello,

    I am wondering if anyone know the answer to this inquiry.

    When one lifts (or shuts off) the throttle on a professional Formula 1 race car does engine braking occur?

    For example, on motorcycles, with a two-stroke engine when one shuts off there is no engine braking at all. With a four-stroke there is engine braking (current technology is untilizing slipper clutches).

    The reason for my question is directly related to go carts.

    I saw the picture of Schumaker go carting on ice and was wondering how his cart compares to his car off throttle.
     
  2. ART360

    ART360 Guest

    On the late style 2strokes there is compression braking when you shut off the engine. The power valves on them make them act like a 4 stroke.

    Art
     
  3. TimN88

    TimN88 F1 Veteran

    Jun 12, 2001
    5,030
    Northeast
    Full Name:
    Tim
    My friend used to have a 2 cycle quad before he upgraded to a raptor, and it did engine brake.
     
  4. beast

    beast F1 Veteran

    May 31, 2003
    8,965
    Lewisville, TX
    Full Name:
    Rob Guess
    As a general rule 4 strokes will have more engine breaking than a 2 stroke engine. But there are several issues that determine how much. For example the engines compression, Valve timing, 2 stroke port timing, crankshaft stroke.

    all of these variables play into the equation. As for the picture os MS on a cart on ice. the cart is using a centrifugal clutch so the second he gets off the gas the clutch is disengaged, the result very little engine breaking.

    Also as Art mentioned that 2 strokes with power valve create engine breaking due to the fact that the Exhaust port is now lower giving more compression. The main thing to remember here is the power valve controlled by electronics or a mechanical system. Most roar race 2 strokes are using an electronic system that slamms the valve shut when the throttle is closed. On most dirt bikes the crank shaft speed controls the power valve and it will stay open when you down shift causing the revs to go up.

    Rob Guess "The Other Rob"
     
  5. PSk

    PSk F1 World Champ

    Nov 20, 2002
    17,673
    Tauranga, NZ
    Full Name:
    Pete
    Yes but from my watching experience the minute they lift they are breaking and the engine is trying to stall!.

    My understanding also is the minute you lift off in an F1 car the downforce effort is so strong the cars slow drastically anyway. I believe that something like half the HP is used to push the air/downforce.

    A go-kart would not act like that :)

    Pete
     
  6. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
    6,374
    Yes, the aero-drag is such that simply lifting off the throttle at max speed (230) will cause the car to decelerate at around 1 Gs. High downforce tracks will have larger deceleration rates simply from drag.
     

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