Recent content by mender

  1. M

    Why is sliding in dirt track racing faster?

    A.T., reread my last post; I think that the amount of force needed to shear a dirt particle from the surface would be much higher than the force from the momentum change imparted by accelerating the particle after shearing. Just my thoughts.
  2. M

    Why are some car engines so loud?

    Nothing comes to mind, Mike, just check the service records and make sure everything is up to date. Most M-B owners are pretty diligent about that though! Danger, the compressor on the SLK should have an automatic clutch only, no shifting or switching (a la Mad Max!) required.
  3. M

    Why are some car engines so loud?

    Good cars, fun and quick, no major issues that I remember (was an M-B shop foreman); anything specific that you're wondering about?
  4. M

    Why are some car engines so loud?

    My pleasure, Danger!
  5. M

    Why are some car engines so loud?

    Top Fuel runs them at about 55 psi boost. Max is around 75psi.
  6. M

    Why are some car engines so loud?

    Two main types of superchargers: positive displacement and centrifugal, the difference being the method of raising the pressure. You can get cross-overs or hybrids but typically for automotive use they are distinct groups. The Roots is a example of a positive displacement air pump. The...
  7. M

    Finding the time it takes to reach 55 mph on paper

    Just a note on the first of your thumbnails: for street tires, the free diameter is the number to use. They don't grow like the slicks used in the higher classes.
  8. M

    Finding the time it takes to reach 55 mph on paper

    If you're using engine dyno graphs and not chassis dyno graphs you also have to factor in powertrain efficiency loss. A 20% drop is typical and will get you close to real numbers. This is what you actually have available at the rear wheels to accelerate the car. After applying the 20% factor...
  9. M

    Stopping Abruptly to Save Break Pads

    Temperature is the issue. Same heat over a shorter period of time = higher temperature. High temp = brake pads wearing out quicker. Using the engine to slow down instead of the brakes = more $$$ spent (brakes are much cheaper than engines, clutches and transmissions). Don't downshift to save...
  10. M

    Need some help determining strut tower load

    First of all, Mike, as usual you're spot on with the load being distributed at multiple points and a wishbone suspension being much better for racing, etc. but I thought the OP was asking specifically about strut towers with the intent of making sure his were strong enough for the loads...
  11. M

    Need some help determining strut tower load

    The direct acting McPherson strut has a lower vertical load and a higher lateral load than the wishbone strut (essentially a coilover, not really a McPherson strut). When changing from direct acting to wishbone, the vertical force increase on the top of the strut tower is the inverse of the...
  12. M

    Automotive Vehicle steady state handling & weight transfer

    No; see tire load sensitivity graph. If they canceled out we wouldn't have to worry about weight transfer or weight distribution or roll couple distribution or ... :tongue:
  13. M

    Automotive Vehicle steady state handling & weight transfer

    1. Adding weight to the front of the car increases the load on the front tires. This results in lower lateral acceleration capability at the front because of load sensitivity of tires. http://en.wikipedia.org/wiki/Tire_load_sensitivity 2. In the case of mild oversteer, mild acceleration will...
  14. M

    Stopping Abruptly to Save Break Pads

    Brake pad and rotor wear are tied pretty closely to peak temperatures reached during braking, all else being equal. Lowering temps by 200F makes a rather large difference in brake life, an especially critical parameter in endurance racing. "Get thee to a punnery!" indeed!:smile:
  15. M

    Automotive Heads are tested need cam help (classic sbc)

    Have you called Comp Cams for their opinion? How long are your races? Why the auto and why a flat tappet cam? Is it a vintage class or something else? Do you have a casting or part number for the heads? What rule restrictions are you working with?
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