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  • The Definition of Acceleration

    I got this email from a friend, pretty interesting!

    --------------------

    Read this thru slowly and try to comprehend the amount of force produced in just under 4 seconds!

    There are no rockets or airplanes built by any government in the world that can accelerate from a standing start as fast as a Top Fuel Dragster or Funny Car!


    DEFINITION OF ACCELERATION

    One top fuel dragster 500 cubic inch Hemi engine makes more horsepower than the first 4 rows of stock cars at the Daytona 500.

    It takes just 15/100ths of a second for all 6,000+ horsepower of an NHRA Top Fuel dragster engine to reach the rear wheels.

    Under full throttle, a dragster engine consumes 1-1/2 gallons of nitro methane per second; a fully loaded 747 consumes jet fuel at the same rate with 25% less energy being produced.

    A stock Dodge Hemi V8 engine cannot produce enough power to drive the dragster's supercharger.

    With 3,000 CFM of air being rammed in by the supercharger on overdrive, the fuel mixture is compressed into a near-solid form before ignition.

    Cylinders run on the verge of hydraulic lock at full throttle.

    At the stoichiometric (stoichiometry: methodology and technology by which quantities of reactants and products in chemical reactions are determined) 1.7:1 air/fuel mixture of nitro methane, the flame front temperature measures 7,050 deg F.

    Nitro methane burns yellow... The spectacular white flame seen above the stacks at night is raw burning hydrogen, dissociated from atmospheric water vapor by the searing exhaust gases.

    Dual magnetos supply 44 amps to each spark plug. This is the output of an arc welder in each cylinder.

    Spark plug electrodes are totally consumed during a pass. After halfway, the engine is dieseling from compression, plus the glow of exhaust valves at 1,400 deg F. The engine can only be shut down by cutting the fuel flow.

    If spark momentarily fails early in the run, unburned nitro builds up in the affected cylinders and then explodes with sufficient force to blow cylinder heads off the block in pieces or split the block in half.

    In order to exceed 300 mph in 4.5 seconds, dragsters must accelerate an average of over 4G's. In order to reach 200 mph (well before half-track), the launch acceleration approaches 8G's.

    Dragsters reach over 300 miles per hour before you have completed reading this sentence.

    Top fuel engines turn approximately 540 revolutions from light to light! Including the burnout, the engine must only survive 900 revolutions under load.

    The redline is actually quite high at 9,500 rpm.

    Assuming all the equipment is paid off, the crew worked for free, and for once NOTHING BLOWS UP, each run costs an estimate $1,000.00 per second.

    The current top fuel dragster elapsed time record is 4.428 seconds for the quarter mile (11/12/06, Tony Schumacher, at Pomona , CA ). The top speed record is 336.15 mph as measured over the last 66' of the run (05/25/05 Tony Schumacher, at Hebron , OH ).

    Putting all of this into perspective:

    You are driving the average $140,000 Lingenfelter 'twin-turbo' powered Corvette Z06. Over a mile up the road, a top fuel dragster is staged and ready to launch down a quarter mile strip as you pass. You have the advantage of a flying start. You run the 'Vette hard up through the gears and blast across the starting line and pass the dragster at an honest 200 mph. The 'tree' (dragstrip start line) goes green for both of you at that moment.

    The dragster launches and starts after you. You keep your foot down hard, but you hear an incredibly brutal whine that sears your eardrums and within 3 seconds, the dragster catches and passes you. He beats you to the finish line, a quarter mile away from where you just passed him.

    Think about it, from a standing start, the dragster had spotted you 200 mph and not only caught, but nearly blasted you off the road when he passed you within a mere 1,320 foot long race course.

    ...... and that my friend, is ACCELERATION!
    RightDrive Inc. Parts Manager
    http://www.rightdrive.ca :: http://www.rightdriveparts.com :: http://www.rightdriveusa.com
    1970 Highway 7 West, Vaughan, ON :: 1-877-398-8220




  • #2
    Very cool!

    Is it the torque or the horsepower that makes this happen? BTW, what's the difference between torque and horsepower? (Not a serious question. I just haven't read a really good discussion of this fundamental concept lately.)

    I did some math comparing the way my car accellerates to a passenger jet and came up pretty impressed with the old grey Skyline.

    Cheers,
    Dan
    sigpic
    The Beaumont Connection

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    • #3
      pretty sure Usain Bolt is the definition of acceleration lol!

      But that was a cool read!
      Originally posted by Paradis
      ^^ hows not being rich going? ...haters be hatin

      Comment


      • #4
        Incredible thank you for that !!
        "LAG is the time the guy beside you thought he won"

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        • #5
          Haha very cool
          Check out the GTST Projects page and keep up to date with my build!
          www.nelsonmx.wordpress.com
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          Any part inquiries can be forwarded to marc@nelsonmx.com

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          • #6
            Originally posted by GTR-Dad View Post
            Very cool!

            Is it the torque or the horsepower that makes this happen? BTW, what's the difference between torque and horsepower? (Not a serious question. I just haven't read a really good discussion of this fundamental concept lately.)

            I did some math comparing the way my car accellerates to a passenger jet and came up pretty impressed with the old grey Skyline.

            Cheers,
            Dan
            *Crunches fingers*

            Torque:

            Force applied around an axis. Force is defined as a quantified potiential of accelaration, applied on a discreet (i.e. infinitely small) point. (Force applied on a square unit is defined as Pressure). Force exerts energy on matter of specific mass to accelerate it, or so until another Force is applied to the mass to mitigate the effect.

            Torque is when the Force is applied to a discreet point at a specific unit of distance from an axis. The result creates a potential to accelerate in rotational motion.

            Horsepower:

            Quantification of the unit of Power or Work vs time. Metric unit of Watt. Work is spent energy for displacing an object while applying a force, or simply a variation in the total energy containted in a mass:

            W=int(x1,x2) F*dx
            W= E1-E2


            Where int: integral and dx is the partial derivation of distance.

            or the scalar (dot product)

            W=F*d*costheta

            Which indicates that Work can be done to oppose the influence of a force when theta is negative. (I still find this facinating since it defines the "dissipation" of a force by leeching it's energy potential, but anyway...I love that aspect of physics)

            Power is simply the Work applied during a certain duration.

            P=W/delta_t

            We can make the correspondance:

            P=F*v

            Where v is velocity. The same is valid for:

            P=T*w

            Where T is Torque w is angular velocity.

            Though, for powerplants such as engines, Energy is created to apply force (create acceleration). Through combustion methods, energy is created in it's mechanical form when the deflagration exerts pressure on the the cylinder head and piston head. The variation of the energy (Work) between the TDC compression and aftermath of ignition in a lapse of time defines the Power created. Since the piston is the only mass capable of accelarating, force is created through it's mass' accelaration and transfered to the crank as Torque.

            So basically, an engine's Torque rating tells you the potential to apply force. Horsepower tells you how much energy can be created in a certain amount of time.

            If we look at:

            P=T*w=F*v

            We see that the car's speed is increased by Power and decreased by exerted force; v=P/F. High velocity can only be acheived by reducing necessary Force output (or Torque!).

            If we look at the force system from a car standpoint, the overall force that is necessary to acheive a certain speed will have to overcome Drag at that speed, among other parasitic variables. Drag would be viewed as vectored in opposite direction to the propelling force.

            Conclusion:

            Horsepower will then indicate, since it will remain constant (as a function of RPM), the maximum speed that the car can overcome Drag, depending on the inertia of the car. E.g.;You can have high horsepower but drain it all in torque because of a heavy vehicle. Horsepower thus keeps an axis of balance between acceleration and speed.

            Torque (potential) will indicate how much you can accelerate the mass of the car under full power (corresponding to the Power function of RPM), if it can overcome inertia, until the system's necessary power at max speed requires the totality of torque available, meaning the car will stop accelerating.




            This is all at the top of my head, it took a quite a while to flesh it out properly, so It was more a fun exercice for myself than anything else. Maybe the whole think is wrong (I wouldn't be surprised if It was, but I'd be dissapointed in my engineering capabilities though )


            ...be gentle if I screwed up.
            1992 BNR32 SKYLINE GTR

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            • #7
              Awesome! just did some wiki searching and found some more facts:

              The oil system has a wet sump which contains 16 quarts of SAE 70 mineral or synthetic racing oil. The pan is made of titanium or aluminium. Titanium can be used to prevent oil spills in the event of a blown rod. Oil pressure is somewhere around 160–170 lbf/in² during the run, 200 lbf/in² at start up

              The pump can flow 100 gallons per minute at 8000 rpm and 500 PSI fuel pressure. In general 10 injectors are placed in the injector hat above the supercharger, 16 in the intake manifold and two per cylinder in the cylinder head.

              Absolute manifold pressure is usually 3.8-4.5 bar (56-66 PSI), but up to 5.0 bar (74 PSI) is possible.

              At maximum throttle and RPM, the exhaust gases escaping from a dragster's open headers produce about 800-1000 pounds (3.6 kilonewtons) of downforce. The massive foil over and behind the rear wheels produces much more, peaking at around 12,000 lbf (53 kN) when the car reaches a speed of about 324 mph (521 km/h).

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              • #8
                Originally posted by Ben @ JNS Imports View Post
                Awesome! just did some wiki searching and found some more facts:

                The oil system has a wet sump which contains 16 quarts of SAE 70 mineral or synthetic racing oil. The pan is made of titanium or aluminium. Titanium can be used to prevent oil spills in the event of a blown rod. Oil pressure is somewhere around 160–170 lbf/in² during the run, 200 lbf/in² at start up

                The pump can flow 100 gallons per minute at 8000 rpm and 500 PSI fuel pressure. In general 10 injectors are placed in the injector hat above the supercharger, 16 in the intake manifold and two per cylinder in the cylinder head.

                Absolute manifold pressure is usually 3.8-4.5 bar (56-66 PSI), but up to 5.0 bar (74 PSI) is possible.

                At maximum throttle and RPM, the exhaust gases escaping from a dragster's open headers produce about 800-1000 pounds (3.6 kilonewtons) of downforce. The massive foil over and behind the rear wheels produces much more, peaking at around 12,000 lbf (53 kN) when the car reaches a speed of about 324 mph (521 km/h).
                Jesus. H. CHRIST.
                1992 BNR32 SKYLINE GTR

                Comment


                • #9
                  That was an insane read! And Ben... Please tell me I read that right. 5.0 BAR?!? Holy hell!
                  Originally posted by kengeroo
                  that's what I thought when I opened the package..
                  ...don't drink and ebay
                  '03 Ford Mustang

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                  • #10
                    Originally posted by Marus92 View Post
                    Conclusion:

                    Horsepower will then indicate, since it will remain constant (as a function of RPM), the maximum speed that the car can overcome Drag, depending on the inertia of the car. E.g.;You can have high horsepower but drain it all in torque because of a heavy vehicle. Horsepower thus keeps an axis of balance between acceleration and speed.

                    Torque (potential) will indicate how much you can accelerate the mass of the car under full power (corresponding to the Power function of RPM), if it can overcome inertia, until the system's necessary power at max speed requires the totality of torque available, meaning the car will stop accelerating.




                    This is all at the top of my head, it took a quite a while to flesh it out properly, so It was more a fun exercice for myself than anything else. Maybe the whole think is wrong (I wouldn't be surprised if It was, but I'd be dissapointed in my engineering capabilities though )


                    ...be gentle if I screwed up.
                    Lot's of good thinking and a WaaaaY better definition of torque and power than most can provide. Internet car forums across the planet would benefit!

                    To summarize, I hear you saying:
                    Torque is how hard you can twist,
                    The harder you twist on a drivetrain, the more force you apply to the road,
                    The more force you apply to the road, the more you accellerate and overcome drag,
                    Horsepower increases with the rotational speed at which you apply torque.

                    So...
                    Accelleration at any given speed is proportional to the driving force (resulting from currently available torque) minus drag. The higher rpm at which an engine can apply torque, the higher the horsepower capability.

                    Also interesting when you're thinking about top speed is that steady state power requirements increase with the cube of speed.

                    Cheers,
                    Dan
                    sigpic
                    The Beaumont Connection

                    Comment


                    • #11
                      pff our skyline can do better than that vette .. joke!
                      Need detailing done to your car? I'm open to travel to detail your car :

                      http://forums.gtrcanada.com/group-buys/54899-ontario-cobraa-detailing-group-buy.html

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                      • #12
                        A person I know had a Top Fueler (rail) back in 1990 when he last raced it. Reached 263mph, 5.5sec 1/4 mile and I think it was the fastest / quickest Top Fueler downunder in 1990. That time, mph was average for Top Fuel dragcars in US at that time. Shows how far they have come in 20 years, 1sec quicker, 73mph faster.

                        Also dyno's measure torque.
                        Last edited by Skym; 01-04-2011, 12:43 PM.
                        RESPONSE MONSTER

                        The most epic signature ever "epic".

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                        • #13
                          Originally posted by GTR-Dad View Post
                          Lot's of good thinking and a WaaaaY better definition of torque and power than most can provide. Internet car forums across the planet would benefit!

                          To summarize, I hear you saying:
                          Torque is how hard you can twist,
                          The harder you twist on a drivetrain, the more force you apply to the road,
                          The more force you apply to the road, the more you accellerate and overcome drag,
                          Horsepower increases with the rotational speed at which you apply torque.

                          So...
                          Accelleration at any given speed is proportional to the driving force (resulting from currently available torque) minus drag. The higher rpm at which an engine can apply torque, the higher the horsepower capability.

                          Also interesting when you're thinking about top speed is that steady state power requirements increase with the cube of speed.

                          Cheers,
                          Dan
                          Exactly. That's also why 90kph yields 177% more fuel efficiency than 120kph (if we assume both would be at same RPM).

                          If you want to know your theoretical top speed;

                          HP (Watt) = HPd = 1/2 rho * v^3 * A * Cd = Fd * v

                          Where rho is air density (or wathever fluid you may be crazy enough to try and drive in), v is velocity, A is the frontal-projected section and Cd is the drag coefficient (0.20 to 0.30 for non-downforced cars).
                          1992 BNR32 SKYLINE GTR

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                          • #14
                            Very nice read. Ive raced a top fuel car in my '70 mustang prolly 7-8 years ago. Somebody took out the tree early that day. Well, they managed to get it up and running but only had 1/8 mile going. (track is too small for 1/4 anyways) So after fixing the lights, it was getting late so they decided to have one prize for the winner. I managed to get the semis before facing the top fuel car. Well what a rush. It was bracket racing so I had quite the head start. I posted a .505 reaction time. Well a few seconds go by and the top fuel car takes off. Well, thought my car shaky before when it crossed the 1/8mile. Well, the top fuel car just beat my by a nose. But it was like we crossed the line at the same moment, it also felt like my car jumped 20' to the side and missed the laser. Still, what a feeling.
                            1970 Ford Mustang Fastback -> Fully Restored with Built 351W Motor
                            1993 Audi S4 -> 2.2L Turbo at 22psi with a few extra go goodies
                            1992 Nissan Skyline GTR -> RB31.5/26 Being Built Now
                            1994 Audi S4 -> Fully Restored and Tastefully Modded, 2.2L Turbo with Hybrid Turbo GT3071/K26 at 25psi

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