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  1. murpia

    Correct handling of tyre rolling resistances: Drive / Coast and 4WD

    Hi, I'm (re)building a MATLAB simulation of longitudinal vehicle dynamics and want to sanity check my handling of tyre rolling resistance power losses: For the Drive case (RWD), I am calculating front tyre rolling resistance losses (P = FV where F = CrrN) only and modelling rear tyre losses as...
  2. murpia

    Vibration standard suitable for an ABS module circuit board

    Hi, Is anyone aware of a public-domain vibration standard suitable for a circuit board of the type that might be housed within an ABS module? Something the board could be submitted to, to validate the mechanical integrity. Thanks, Ian
  3. murpia

    Touring car rear suspension

    I don't think the centre hard-point is meant to attach to the body. If my hunch is correct then this replaces a twist-beam, so the hard-points are only the front mounts of each fabrication, and the top mounts of the springs / dampers. The ARB may be something the original car did not have? The...
  4. murpia

    Touring car rear suspension

    I've no idea what to call that suspension but it seems to me it exists to: fit onto the chassis pickup points of a twist-beam rear axle be stiff (low compliance effects) be adjustable in camber be adjustable in toe Regards, Ian
  5. murpia

    Equal performance V4 vs V6 engine length

    Thanks! This is where I was coming from, you'd have to really want it, to make it worthwhile. Regards, Ian
  6. murpia

    Equal performance V4 vs V6 engine length

    Hi Jack, Agreed, Volumetric Flow Rate seems to be a better comparison. Here's my original reasoning on the stroke: The V4 will have larger diameter, therefore heavier, pistons. So to keep the crank / rod / piston stresses at similar levels the mean piston speed (and therefore stroke) needs...
  7. murpia

    Equal performance V4 vs V6 engine length

    Just speculating on the likely shortest engine for a given performance (based on equal swept volume & maximum revs): V4 would have 2x larger bore diameter vs. 3x smaller bore diameter for V6 V4 would need shorter stroke to achieve similar revs to V6, so slightly larger bore again 'lost' length...
  8. murpia

    all wheel drive center differential two way sprag

    There's an error above, I wrote: "If the front rotates 5% slower than the rear", should be "If the front rotates 5% faster than the rear..."
  9. murpia

    all wheel drive center differential two way sprag

    Wow, that's the first time I ever got cross-quoted from another forum... The idea of using a one-way sprag instead of a centre diff has a merit in motorsport I think. I'm not so sure about daily driving and the original post does not clarify. I understand 4WD off road vehicles used to be built...
  10. murpia

    injector driver

    Saturated injectors just need a mosfet + zener, or an avalanche rated mosfet. Logic level adds convenience. Google 'microsquirt injector drivers' or 'JBPerf 4-channel' for suggestions. Regards, Ian
  11. murpia

    Estimation of the flywheel torque from the combustion torque

    Sounds like the main data missing is the friction of the engine: Crank torque = (Combustion torque) - (Friction torque) Regards, Ian
  12. murpia

    "new" roll/sway bar concept

    My take: The 'fully floating spring damper unit' and the 'nik link' are two distinct things. The former increases damper travel relative to wheel travel and possibly introduces a rising rate correction to the otherwise falling rate you would get if the spring damper were direct mounted. I...
  13. murpia

    Half-shaft torsional damping

    Thanks Greg, I can understand where the damping comes from in the elastomer versions, but not the bolt-on masses. Maybe they are trying to create two stiffer shafts connecting an inertia? Regards, Ian
  14. murpia

    Half-shaft torsional damping

    Hi, FWD cars often seem to use a clamp-on or spline-on torsional damper. Some seem to be simple masses, others have an elastomer component too. Can anyone point me to a calculation of how these dampers work, and what their capabilities are? Google just throws up countless references to parts...
  15. murpia

    hand brake turns with AWD

    'Aggressive use of the handbrake in motion was always a good way to break halfshafts on early range rovers.' Front or rear? Regards, Ian
  16. murpia

    hand brake turns with AWD

    With a completely free geared centre diff, locking the rear axle will decelerate the engine to half speed. While this requires more torque from the handbrake than just locking the rear axle does, there's no reason this cannot be done. So an active geared centre diff, which unlocks...
  17. murpia

    Z bar

    In fitting a 'Z' bar you are trading roll stiffness against heave stiffness. Have you already disconnected the front anti-roll bar ('U' bar)? Have you already / can you afford to soften the front side springs? Do you need more front heave stiffness? Regards, Ian
  18. murpia

    Is there any relay which can be programmed to work under certain voltage, current or load range?

    Try one of these: http://www.we-online.com/web/en/intelligente_systeme/produkte_neu/steuerungen_sensoren/iccs_kleinsteuerungen/ICCS_Kleinsteuerungen.php Regards, Ian
  19. murpia

    current F1 front suspension

    The geometric front roll centre of that Ferrari looks to be about 275mm high to me. Hardly catastrophic, but definitely not ground level. Regards, Ian
  20. murpia

    estimate BSFC sweetspot for partial load

    I didn't have much luck Googling for a cheap / free OBD port data logger. That surprised me a bit as I thought it would be a common thing to want and someone would have produced a freeware version by now. I have one of those ELM327 USB scan tools, which use a virtual COM port. Looks like the...

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