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  1. R

    Calculating 0-60 mph time for a vehicle

    Another way of finding torque at the wheel at top speed is looking at power of the forces resisting acceleration. I have to get to work, so I'll just say that the equations for A and C that you posted in the other thread are exactly what I think is correct. You can replace CRR with a more...
  2. R

    Test Driving a Car Virtually

    My post will be short today as time has just disappeared somehow. I'll go back and try to do some metric unit examples later. SI are what I'm used to, so it is easier for me. Today I think I'll just give some idea of where I'm heading with all of this in case someone wants to work it out faster...
  3. R

    Calculating 0-60 mph time for a vehicle

    Ok, you might be right about the gear box. I couldn't find the spot on the Renault site that gave the transmission details, so I looked on other sites. I went back to those sites, and I saw they also mentioned a petrol engine. They are obviously talking about a different car. When I finally got...
  4. R

    Calculating 0-60 mph time for a vehicle

    Ok, the problem here is the engine power drops off if you start adding a drop in voltage. This is the steep drop off point I mentioned. I'm aware of this point, but this point does not equal constant power. Your torque is dropping at that point, because your power is dropping much faster than...
  5. R

    Calculating 0-60 mph time for a vehicle

    What you are describing doesn't make sense according to the laws of physics. We know speed is going up, because you say that the car is going from 25mph to 70mph. We know the Flunce Z.E. doesn't have a continuously variable transmission, and you are saying you want to assume it is in one gear...
  6. R

    Calculating 0-60 mph time for a vehicle

    You know I take that back. Power can be constant on a CVT. A CVT actually constantly changes the gear ratio's to keep the engine at the same speed as the tires change speed. Whether they set it up for RPM's at peak torque or peak power will depend on if they care more about fuel economy or...
  7. R

    Calculating 0-60 mph time for a vehicle

    Most of your assumptions are wrong here. I don't mean to mean, they just are. For one, the engine torque does not equal the tire torque. If we are in top gear, then the tires normally have half the torque then the engine, because they are turning twice as fast. The power at the engine is also...
  8. R

    Maximum radius given rps, static and kinetic friction coefficients

    Correct. Static friction is a ratio that represents how well two things are stuck together. It is all that applies until we have movement between the objects. Once we have movement you kind of get a skipping motion on the microscopic level. Think of it like two pieces of metal that have fitting...
  9. R

    Maximum radius given rps, static and kinetic friction coefficients

    There are a couple of things to consider here. The first thing is understanding the forces on the object. F_M = \mu_s * F_N F_M = Maximum force of friction \mu_s = Static coefficient of friction F_N = Normal force Static friction doesn't always produce a force. It only produces a...
  10. R

    Test Driving a Car Virtually

    In an ideal world the power from the engine would go directly toward moving the vehicle. We already saw this was not happening in the engine. Gasoline has a given potential energy per mass, but the power of our engine did not increase purely based on the amount of gasoline burned. A four stroke...
  11. R

    Test Driving a Car Virtually

    So my starting point is the equation for acceleration based on power. A(t) = P(V(t))/ (M * V(t)) A = Acceleration t = Time P = Power V = Velocity M = Mass My first goal is to come up with an equation for power based on velocity as velocity changes over time. The first component of power that...
  12. R

    Test Driving a Car Virtually

    I played around in another thread with mathematically determining where a car should be time wise on 1/4 mile run. I had a chance to drive this car myself giving me more information than you normally have on a car you have yet to buy. As I thought more deeply about my calculations, I became...
  13. R

    Calculating 0-60 mph time for a vehicle

    I think your biggest mistake is probably where you started using T / r with T = engine torque, and r = wheel radius. The wheel radius alone is not enough, because the torque on the wheel is dependent both on the gear ratio and the velocity of the car. Unless you are assuming that power is on a...
  14. R

    Calculating 0-60 mph time for a vehicle

    What values are you using with units. It is hard to check where you might be going wrong, if I don't know the details of the object you are trying to make calculations for.
  15. R

    Ideal 1/4 mile time from Average Power

    Ok, let me try this again. I want to be able to enter the appropriate V0 every run, so I need to work that into the equation. v2 = 2c2 [t/c −C1] With t = 0, I should have: v2 = -2c2C1 Meaning: C1 = v2/-2c2 Plugging that back into the equation gives us: v2 = 2c2 [t/c − v2/-2c2] = 2tc +...
  16. R

    Ideal 1/4 mile time from Average Power

    I can always work on low gear ratios later to improve low rev power delivery. At the moment, my key concern is power loss at the speed and revs the car is normally going to be moving through. This is all a rough rationalization fro a starting point. I'm just trying to kick out the types of...
  17. R

    Ideal 1/4 mile time from Average Power

    That should do it. C1 needed to be -v02/2c2. When you plug it back into the equation the 2c2 cancels out. Now I just have to be careful to remember pound force in power assumes 32.174 ft/s2 over it's 550 pound feet per second. That's the biggest problem with pounds is remembering if you are...
  18. R

    Ideal 1/4 mile time from Average Power

    Something is still wrong. with that last change, I end up with negative time. I'll have to check C1 again when I get another chance in a couple hours.
  19. R

    Ideal 1/4 mile time from Average Power

    Ok, I did several things wrong. I'll make a new post with the corrected math. This is perfect. The application of this is that I have three cars with similar engine compartments, so they have similar possibilities when it comes to power. They don't have similar losses in acceleration due to...
  20. R

    Ideal 1/4 mile time from Average Power

    That last bit from Dauto is exactly what I was looking for. I think I'll play around with the work-energy theory on my own to see what I get there. Power is work over time, so I think I see where you are going with that. Thanks.
  21. R

    Ideal 1/4 mile time from Average Power

    None of this is quite what I'm looking for, so I think I'll start with the direction I'm trying to go in mathematically. I'm making this as a perfect world problem, because I want to start with the basic equation before I start adding in power loss. I know that my starting point is: A(t) =...
  22. R

    Ideal 1/4 mile time from Average Power

    I'm wanting to get the time it would take a vehicle to travel a 1/4 mile coming out of a corner in the ideal world. By ideal I mean that I'm assuming there is no energy loss to friction, wheel slippage, drag, or heat. I want to avoid using gear ratios, and since it is an ideal world I'm assuming...
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