Continue to Site

Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

  • Congratulations cowski on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Recent content by hpfreak

  1. hpfreak

    Moving air from first floor to second floor...CFM?

    I installed a wood stove in my first floor living room. The temp in this room easily gets in the mid-80's with even the smallest slow burn fire, while the rest of the house hovers around 75 on the first floor and 70 on the second. Finally to the question.. I am installing a duct in the...
  2. hpfreak

    Objectively measuring and defining subjective steering "feel"

    IMO much of the steering feel is system compliance. Focusing on rack bushings, tire sidewalls and response, control arm bushings, body/frame stiffness and weight distribution, not just boost and ratio will round out the package. Minimizing compliance goes a long way to helping steering, but must...
  3. hpfreak

    methods to measure steering wheel inertia and friction?

    Ok, you disagree. How about methods of measurment?
  4. hpfreak

    methods to measure steering wheel inertia and friction?

    Steering system friction is important on the "driver side" of the system more than the "hydraulic side". The difference is the driver side is unboosted and the hydraulic side is boosted. Friction has a large affect on steering feel and returnability on the driver side. You can measure the...
  5. hpfreak

    Mixed suspension types

    Depending on the initial angle of the lower control arm for the rear, the roll center will rise or fall in roll. This can give a different roll feel to the entire vehicle. A falling rc can give an awkward feeling to the driver.
  6. hpfreak

    Roll axis inclination

    Interesting post, and quite a mouthfull! "Inclining the roll axis also has effects on TLLTD. If it is inclined so that it goes up as it moves rearward, there will be a larger TLLTD to the rear suspension from the RCH contributions. This could probably be easily mitigated by tuning the Anti...
  7. hpfreak

    manifold runner and half-order noise

    This is a topic for the engine forum, there is a wealth of discussion about manifolds there. my $0.02: 1) Equal length runners are good for balanced cylinders. However, it does not gaurantee it. Flow balance and equal length runners must be developed. 2.) Half order pulses can be generated...
  8. hpfreak

    Chassis/Body Roll Inertia values

    SAE paper # 1999-01-1336.
  9. hpfreak

    Roll Steer Plot

    Work with your tire supplier to help you tune this condition. Does this sportier version get a new tire? Can you change body mounting points? If you raise the rear roll center, it will speed the response of the rear and decrease the roll bar rate required. This could decrease the toe change.
  10. hpfreak

    Roll Steer Plot

    It sounds like you are slowly but surely tracking down this problem. I would agree that any kinks or changes in a toe curve are a bad thing and you should minimize that first. I think that will help you out. Do you know the toe pattern w/o roll bar? Does it smooth the toe curve? Don't limit...
  11. hpfreak

    Suspension design/car design and outcomes

    In my mind, the major factor would be c.g location. The front engine placement typically results in front weight bias. This is a more stable condition b/c the heaviest loaded tires give up first. If they are in the front, you get understeer, if it's in the back you get oversteer. When you have...
  12. hpfreak

    Important suspension parameters

    Anti-x spindle length roll steer hub trail
  13. hpfreak

    Keeping Intake cold and exhaust hot?

    Plastic intakes are good for a 2-3% gain over an identical aluminum intake for two reasons. 1) They don't transfer as much heat to the intake charge. 2) The surface finish is much better than cast Al. One way to improve the heat problem with al intakes is the thermal isolator gaskets available...
  14. hpfreak

    Roll Center Position & Migration

    I think a diagram should prove there is no difference at the tires. The inputs dont change(cg*cornering acceleration) and the outputs dont change(tire reactions)It may change the motion of the chassis from pure roll to combination roll and bump. Because of the asymmetric roll axis. I dont...
  15. hpfreak

    Roll Center Position & Migration

    I think of horizontal roll center movement like an imaginary number. It's significance is questionable and is mainly used to calculate the vertical position. The vertical movement is the real concern and the one that shows up in all the loading equations. Once you get into roll/dive (turn-in?)...

Part and Inventory Search