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  1. pontiacjack

    Automatic Transmissions

    enginesrus- Dual Range Hydramatics almost had a direct drive in 3rd gear and 4th gear. But a small fraction of the torque still passed through the fluid coupling in those gears.
  2. pontiacjack

    Clarification of Timing Belt Systems

    Besides pitch, the tooth profile and width of sprockets must match the belt. And of course the belt parameters must meet or exceed the dynamic requirements (load, speed, durability, etc.). Functionally, the pitch diameters of the sprockets is most important (number of teeth times pitch divided...
  3. pontiacjack

    Exhaust drone causes, and reduction techniques

    I'm peeved that I may need to get involved with engineering drone out of exhaust systems. I shouldn't need to, but driving vehicles that are at least 50 years old places me at the mercy of retailers of replacement mufflers. There is no alternative but trial and error- which is both expensive and...
  4. pontiacjack

    NVH and natural frequency

    Nice work. Thanks for posting the patterns. Glad your persistence paid off.
  5. pontiacjack

    Estimate of gains when converting to thinner piston rings

    I can't answer your question. But many of us use modern-era "thin" rings in competition engines for only one reason- to [hopefully] avoid "flutter" at ultra-high piston speeds and accelerations (up to 8,600 g). In other words, we're only looking for better sealing of the combustion space under...
  6. pontiacjack

    About Cylinder Pressure

    The 1966 Chrysler plot clearly shows that bearings need to be much more concerned with loads created by rod/piston inertia than by combustion events; at least for "modern high-speed" engines.
  7. pontiacjack

    Chassis torsional stiffness 1965 and today

    Noah- "... deflections that are no more than a few % of the length over which they're measured..." does not relate to the angular deflection of one end of a chassis. Perhaps you meant "deflections that are no more than a few % of the value which causes deformation"? jgKRI- How did you conclude...
  8. pontiacjack

    Chassis torsional stiffness 1965 and today

    In this thread I count at least 14 examples of chassis torsional rigidity values. But none of them (other than my two) specify the total angular deflection used for measurement. Why not? Can't some of you provide some numbers? Or perhaps provide a reference to an industry-standard?
  9. pontiacjack

    Chassis torsional stiffness 1965 and today

    I see from my notes that I misspoke above- my test only involved half a degree of twist; holding a torque wrench steady at over 100 lb.ft. was not easy for me. I simply multiplied my readings times two to get the 95/135 numbers...
  10. pontiacjack

    Chassis torsional stiffness 1965 and today

    Every torsional stiffness number in this thread amazes me. When I re-did my '59 GMC pickup (from the ground up), I knew the frame design wasn't very rigid (just C-channels) and tried to improve it. To measure any improvement (of the bare chassis) I put the extreme rear of the frame on jack...
  11. pontiacjack

    Peak Pressure Inside the Internal Combustion Engine

    Be advised: that inertial forces on the rod (of total reciprocating mass- piston, etc.) will typically exceed any combustion-related forces at the engine speed you're concerned about. One quick example is an engine I'm building- with a 3.62" stroke, the acceleration at TDC at 10,000 RPM is 8,400...
  12. pontiacjack

    NVH and natural frequency

    Thanks for the pictures. Let us know the outcome.
  13. pontiacjack

    NVH and natural frequency

    I really don't know- I was just tossing out some thoughts. Did you really connect the subframe connectors to the "... rear of the front subframes..." as you said? Here's why I ask: my daily driver '67 Falcon is badly rusted, especially the torque-box areas, although all four subframes are still...
  14. pontiacjack

    Flywheel fastener design, clamping force and dowel shear strength

    Plenty of successful schemes that use only "clamp" fasteners to survive high shear forces- for instance ring gear mounting on differential cases, which transmit WAY more torque than the vehicle's flywheel.
  15. pontiacjack

    NVH and natural frequency

    Random thoughts: Flat-crank inline engines have a 2nd order imbalance that the Falcon six did not have. Taming it has caused much development (and many balance shafts implemented) by auto manufacturers. They weren't very successful with the '63 Tempest four I had. Perhaps some portion of the...
  16. pontiacjack

    Rubber o-ring head

    Just thinkin' out loud; if I were looking at that as a designer, I'd consider a labyrinth-type seal scheme, by providing a protruding ring (of native head material) that would extend down into the O-ring groove a relatively small distance (.040"?), with fairly close radial fit to the groove...
  17. pontiacjack

    Bad contact pattern gearset

    Maybe I'm seeing it wrong, but it appears to me that the picture is of the so-called "coast" side of the teeth, not the "drive" side?
  18. pontiacjack

    Air Fuel Ratios for NA Engines

    I also can't see your table. But simply stating "... 12.5:1 at any RPM..." with no mention of load value is not very meaningful. At full load a ratio of less than 12:1 would be typical, and at light load stoichiometric (14.7:1) usually works well.
  19. pontiacjack

    4 cyl. crankshaft excitations.

    Let's see if I get thrown off here for hijacking this thread... I need to know a representative (ballpark) maximum value of repetitive (vibratory) crankshaft angular acceleration (supercharged 3 liter inline four cylinder) at ~10,000 RPM (shooting for 725 HP @ ~9,000 RPM). The only "dampers"...
  20. pontiacjack

    Engine test engineer getting a bit overwhelmed by vibration analysis

    I'm needing to learn representative values of cyclic torsional accelerations (and jerk) that an inline four cylinder engine's crankshaft experiences, for a crankshaft modification I'm considering. Scanning a list of SAE papers showed quite a number of papers which should be helpful [but I've yet...

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